Note: Descriptions are shown in the official language in which they were submitted.
CA 02901455 2015-08-25
TITLE
POROUS CARBON MATERIALS FOR CO2 SEPARATION IN NATURAL GAS
RELATED APPLICATIONS
[1] This application claims priority to and benefit of U.S. Provisional Patent
Application No.
62/079,437, filed on November 13, 2014; is a continuation-in-part of U.S.
Patent Application
No. 14/458,802 filed on August 13, 2014, which claims priority to and benefit
of U.S.
Provisional Patent Application No. 61/865,323, filed on August 13, 2013 and
U.S. Provisional
Patent Application No. 62/001,552, filed on May 21, 2014; is a continuation-in-
part of U.S.
Patent Application No. 14/315,920, filed on Jun 26, 2014, which claims
priority to and the
benefit of U.S. Provisional Patent Application No. 61/839,567, filed on June
26, 2013; and is a
continuation-in-part of U.S. Patent Application No. 14/371,791, filed on July
11, 2014, which is
a U.S. national stage application of PCT/US2013/021239, filed on January 11,
2013, and which
claims priority to and benefit of U.S. Provisional Patent Application No.
61/585,510, filed on
January 11, 2012. The entirety of each of the aforementioned applications is
incorporated herein
by reference.
BACKGROUND
[2] Current methods and materials for capturing CO2 and H2S from an
environment suffer from
numerous limitations, including low selectivity, limited sorption capacity,
high sorbent costs, and
stringent reaction conditions. The present disclosure addresses these
limitations.
SUMMARY
[3] In some embodiments, the present disclosure pertains to methods of
capturing a gas from an
environment. In some embodiments, the methods include a step of associating
the environment
with a porous carbon material. In some embodiments, the associating results in
sorption of gas
components to the porous carbon material. In some embodiments, the sorbed gas
components
include at least one of CO2, H2S, and combinations thereof.
[4] In some embodiments, the environment in which gas capture occurs is a
pressurized
environment. In some embodiments, the environment includes, without
limitation, industrial gas
streams, natural gas streams, natural gas wells, industrial gas wells,' oil
and gas fields, and
combinations thereof.
CA 02901455 2015-08-25
[5] In some embodiments, the sorbed gas components include CO2. In some
embodiments, the
sorption of the CO2 to the porous carbon material occurs selectively over
hydrocarbons in the
environment. In some embodiments, the CO2 is converted to poly (CO2) or a
matrix of CO2
(e.g., a matrix of ordered CO2) within the pores of the porous carbon
materials. In some
embodiments, the porous carbon material has a CO2 sorption capacity of about
50 wt% to about
200wt% of the porous carbon material weight when measured in absolute uptake
values.
[6] In some embodiments, the sorbed gas components include H2S. In some
embodiments, the
H2S is converted within the pores of the porous carbon materials to at least
one of elemental
sulfur (S), sulfur dioxide (SO2), sulfuric acid (H2SO4), and combinations
thereof. In some
embodiments, the formed elemental sulfur becomes impregnated with the porous
carbon
material. In some embodiments, captured H2S remains intact within the porous
carbon material.
In some embodiments, the porous carbon material has a H2S sorption capacity of
about 50 wt%
to about 300 wt% of the porous carbon material weight.
[7] In some embodiments, the sorbed gas components include CO2 and H2S. In
some
embodiments, the sorption of II2S and CO2 to the porous carbon material occurs
at the same
time. In some embodiments, the sorption of CO2 to the porous carbon material
occurs before the
sorption of H2S to the porous carbon material. In some embodiments, the
sorption of H2S to the
porous carbon material occurs before the sorption of CO2 to the porous carbon
material.
[8] In some embodiments, the methods of the present disclosure also include a
step of releasing
captured gas components from the porous carbon material. In some embodiments,
the releasing
occurs by decreasing the pressure of the environment or heating the
environment. In some
embodiments, the releasing of sorbed CO2 occurs by decreasing the pressure of
the environment
or placing the porous carbon material in a second environment that has a lower
pressure than the
environment where CO2 capture occurred. In some embodiments, the releasing of
sorbed 1I2S
occurs by heating the porous carbon material. In some embodiments, the
releasing of the CO2
occurs before the releasing of the H2S.
[9] In some embodiments, the methods of the present disclosure also include a
step of disposing
the released gas. In some embodiments, the methods of the present disclosure
also include a step
2
CA 02901455 2015-08-25
of reusing the porous carbon material after the releasing to capture
additional gas components
from an environment.
[10] In some embodiments, the porous carbon material utilized for gas capture
includes a
plurality of pores. In some embodiments, the porous carbon material includes,
without limitation,
protein-derived porous carbon materials, carbohydrate-derived porous carbon
materials, cotton-
derived porous carbon materials, fat-derived porous carbon materials, waste-
derived porous
carbon materials, asphalt-derived porous carbon materials, coal-derived porous
carbon materials,
coke-derived porous carbon materials, asphaltene-derived porous carbon
materials, oil product-
derived porous carbon materials, bitumen-derived porous carbon materials, tar-
derived porous
carbon materials, pitch-derived porous carbon materials, anthracite-derived
porous carbon
materials, melamine-derived porous carbon materials, biochar-derived porous
carbon, wood-
derived porous carbon and combinations thereof.
[11] In some embodiments, the porous carbon material includes asphalt-derived
porous carbon
materials. In some embodiments, the porous carbon material is carbonized. In
some
embodiments, the porous carbon material is reduced. In some embodiments, the
porous carbon
material is vulcanized. In some embodiments, the porous carbon material
includes a plurality of
nucleophilic moieties. In some embodiments, the nucleophilic moieties include,
without
limitation, oxygen-containing moieties, sulfur-containing moieties, metal-
containing moieties,
metal oxide-containing moieties, metal sulfide-containing moieties, nitrogen-
containing
moieties, phosphorous-containing moieties, and combinations thereof
1121 In some embodiments, the porous carbon materials may be derived from at
least one of
biochars, hydrochars, charcoals, coal, activated carbon, and combinations
thereof. These
sources may be favorable when other sources (such as asphalt) are
prohibitively expensive for a
particular application. The cost of synthetic polymers may be seen as high
compared with
industrial waste or agriculture waste. Furthermore, in order to reach higher
CO2 uptake capacity,
A-PC has to be N-doped by NH3 followed by 112 reduction at 700 C, which may
not be favored
by all industries. In some embodiments, the porous carbon materials of the
present disclosure
are biochar-derived porous carbon materials (B-PC). In some embodiments, the
porous carbon
materials of the present disclosure are biochar-derived and nitrogen-
containing porous carbon
3
CA 02901455 2015-08-25
materials (B-NPC). In some embodiments, the biochar source is a carbon-rich
material produced
by pyrolysis of waste organic feedstock that has been used as a sustainable
means to sequester
atmospheric carbon, improve soil fertility, waste management and to reduce CO2
emissions. In
some embodiments, the porous carbon materials of the present disclosure have a
1.50 g of CO2
uptake capacity per gram of sorbcnt, which is ¨ 5 times higher than that in
Zeolite 5A and 3
times higher than that in ZIF-8 measured under the pressure of 30 bar at 23
C. In some
embodiments, the porous carbon materials of the present disclosure (e.g., B-PC
and B-NPC) can
be spontaneously regenerated when the pressure returns to ambient pressure
with the same CO2
uptake performance-- a pressure swing capture process. In some embodiments,
the porous carbon
materials of the present disclosure (e.g., B-PC and B-NPC) can also be used as
metal-free
catalysts as well as sorbents for low-temperature oxidation of H2S to
elemental sulfur. In some
embodiments, the biochars of the present disclosure (e.g., sulfur-rich B-PC
and sulfur-rich B-
NPC) can be potentially used as cathode materials in lithium-sulfur batteries.
[13] In some embodiments, the porous carbon materials have surface areas
ranging from about
2,500 m2/g to about 4,500 m2/g. Surface areas greater than about 3,000 m2/g
may imply that the
sorbent stacks into multilayers within the pore structures and along the
surfaces. In some
embodiments, the plurality of pores in the porous carbon material comprises
diameters ranging
from about 1 nm to about 10 nm, and volumes ranging from about 1 cm3/g to
about 3 cm3/g. In
some embodiments, the porous carbon material has a density ranging from about
0.3 g/cm3 to
about 4 g/cm3.
[14] Additional embodiments of the present disclosure pertain to the porous
carbon materials
used for gas capture or gas separation or combinations thereof. Further
embodiments of the
present disclosure pertain to methods of making the porous carbon materials of
the present
disclosure.
DESCRIPTION OF THE FIGURES
[15] FIGURE 1 shows a scheme of a method of utilizing porous carbon materials
to capture gas
(e.g., carbon dioxide (CO2) or hydrogen sulfide (H2S)) from an environment
(FIG. 1).
4
CA 02901455 2015-08-25
[16] FIGURE 2 shows schemes of CO2 capture from materials relating to the
formation of
chemisorbed oxygen species on porous carbon materials as a result of their
reaction with H2S
and 02. The porous carbon material was first reacted with H2S and air, and
then thermalized with
or without ammonia, and finally used for reversible CO2 capture.
[17] FIGURE 3 shows synthetic schemes and micrographic images of various
porous carbon
materials. FIG. 3A provides a scheme for the synthesis of sulfur-containing
porous carbon (SPC)
or nitrogen containing porous carbon (NPC) by treating poly[(2-
hydroxymethyl)thiophene] or
poly(aerylonitrile) with KOH at 600 C and then washing with dilute HC1 and
water until the
extracts are neutral. The NPC is further reduced using 10% H2 at 600 C to
form reduced NPC
(R-NPC). The synthetic details are described in Example 1. FIG. 3B shows a
scanning electron
microscopy (SEM) image of NPCs at a scale bar of 100 p.m. FIG. 3C shows an SEM
image of
SPCs at a scale bar of 500 nm. FIG. 3D shows a transmission electron
microscopy (TEM) image
of the SPCs in FIG. 3B at a scale bar of 25 nm.
[18] FIGURE 4 shows x-ray photoelectron spectroscopy (XPS) of SPCs (left
panel) and NPCs
(right panel). The XPS indicates 13.3 atomic % of S in the SPC precursor and
22.4 atomic % of
N in the NPC precursor. The resulting SPC and NPC then had 8.1 atomic % of S
content and 6.2
atomic % of N content, respectively. The S2p and Ni, XPS peaks were taken from
the SPC and
NPC. The S2p core splits into two main peaks of 163.7 (2p312) and 164.8 eV
(2p112), which
correspond to thiophenie sulfur atoms incorporated into the porous carbon
framework via the
formation of C-S-C bond. The Ni reflects two different chemical environments:
pyridinic
nitrogen (N-6) and pyrrolic nitrogen (N-5) atoms.
[19] FIGURE 5 shows data relating to CO2 uptake measurements for SPCs. FIG. 5A
shows
volumetric and gravimetric uptake of CO2 on SPC at different temperatures and
pressures. Data
designated with (*) were recorded volumetrically. Data designated with ( )
were performed
volumetrically. Data designated with (+) were measured gravimetrically at
NIST. All gravimetric
measurements were corrected for buoyancy. FIGS. 5B-D show three consecutive
CO2 sorption-
desorption cycles on the SPC over a pressure range from 0 to 30 bar at 30 C.
All solid circles
indicate CO2 sorption, while the open circles designate the desorption
process. FIG. 5E show
volumetric SPC CO2 sorption isotherms at 23 C and 50 C over a pressure range
from 0 to 1 bar.
CA 02901455 2015-08-25
[20] FIGURE 6 shows pictorial descriptions of excess and absolute CO2 uptake.
FIG. 6A is
adapted from Chem. Sci. 5, 32-51 (2014). The dashed line indicates the Gibbs
dividing surface.
It divides the free volume into two regions in which gas molecules are either
in an adsorbed or
bulk state. FIG. 6B shows a depiction of total uptake, which can be used as an
approximation for
absolute uptake for microporous materials with negligible external surface
areas.
[21] FIGURE 7 shows CO2 uptake on the SPC. Comparison of absolute uptake and
excess
uptake at 22 C and 50 C exemplifies the small differences over this pressure
and temperature
range.
[22] FIGURE 8 shows spectral changes before and after sorption-desorption at
23 C and the
proposed polymerization mechanism. Attenuated total reflectance infrared
spectroscopy (ATR-
IR) (FIGS. 8A-B), Raman spectroscopy (FIG. 8C) and 50.3 MHz I3C MAS NMR
spectra (FIG.
8D) are shown before and after CO2 sorption at 10 bar and room temperature.
All spectra were
recorded at the elapsed times indicated on the graphs after the SPC sorbent
was returned to
ambient pressure. In the NMR experiments, the rotor containing the SPC was
tightly capped
during the analyses. For the third NMR experiment (top), the same material was
left under
ambient conditions for 19 h before being repacked in the rotor to obtain the
final spectrum. Each
NMR spectrum took 80 mm to record. Example 1 shows more details. FIGS. 8E-F
show
proposed mechanisms that illustrate the poly (CO2) formation in SPC or NPC,
respectively, in a
higher pressure CO2 environment. With the assistance of the nucleophile, such
as S or N, the CO2
polymerization reaction is initiated under pressure, and the polymer is
further likely stabilized by
the van der Waals interactions with the carbon surfaces in the pores.
[23] FIGURE 9 shows ATR-IR (FIG. 9A) and Raman (FIG. 9B) spectra for the ZIF-8
before
and after CO2 sorption at 10 bar. All spectra were recorded 3 and 20 minutes
after the ZIF-8
sorbent was returned to ambient pressure at room temperature.
[24] FIGURE 10 shows ATR-IR (FIG. 10A) and Raman (FIG. 10B) spectra for the
activated
carbon before and after CO2 sorption at 10 bar. Spectra were taken 3 min and
20 min after the
activated carbon was returned to ambient pressure at room temperature.
6
CA 02901455 2015-08-25
[25] FIGURE 11 shows volumetric gas uptake data. FIG. 11A shows data relating
to volumetric
CO2 uptake performance at 30 C of SPC, NPC, R-NPC and the following
traditional sorbents:
activated carbon, ZIF-8, and zeolite 5A. Aluminum foil was used as a reference
to ensure no CO2
condensation was occurring in the system at this temperature and pressure.
Volumetric CO2 and
CH4 uptake tests at 23 C on SPC (FIG. 11B), activated carbon (FIG. 11C) and
ZIF-8 sorbents
(FIG. 11D) are also shown.
[26] FIGURE 12 shows various mass spectrometry (MS) data. FIG. 12A shows MS
data that
was taken while the system was being pressurized with a premixed gas of CO2 in
natural gas
during the uptake process. FIG. 12B shows MS data that was recorded while the
premixed gas-
filled SPC was desorbing from 30 bar. The mixed gas was purchased from Applied
Gas Inc.
[27] FIGURE 13 shows comparative data relating to the CO2 uptake capacities of
various carbon
sources.
[28] FIGURE 14 shows scanning electron microscopy (SEM) (FIG. 14A) and
transmission
electron microscopy (TEM) (FIG. 14B) images of A-PCs.
[29] FIGURE 15 shows nitrogen sorption isotherms for A-PC, A-NPC and A-rNPC.
[30] FIGURE 16 shows schematic illustrations of the preparation of asphalt-
derived porous
carbon materials (A-PCs). FIG. 16A shows a scheme of a method of preparing
nitrogen-doped
A-PCs (A-NPCs) and reduced A-NPCs (A-rNPC). FIG. 16B shows more detailed
schemes of
methods of preparing A-rNPCs, sulfur-doped APCs (A-SPC), and nitrogen-doped
and sulfur
doped APCs (A-NSPCs).
[31] FIGURE 17 shows a comparison of room temperature volumetric CO2 uptake of
A-PC, A-
NPC and A-rNPC with the other porous carbon sorbents and the starting asphalt.
[32] FIGURE 18 shows data relating to the volumetric uptake of CO2 on A-rNPC
as a function
of temperature at pressures that range from about 0-30 bar (FIG. 18A) and
about 0-1 bar (FIG.
18B).
[33] FIGURE 19 shows data relating to the volumetric CO2 and CH4 uptake of A-
rNPC
(squares) and A-SPC (circles) at 23 C.
7
CA 02901455 2015-08-25
[34] Figure 20 shows the gravimetric measurement of CO2 and CH4 uptake of uGil-
600, 700,
800, and 900 at 25 C. The uGil-T sorbents exhibit high CO2 capacity (up to
1.50 g CO2/g
adsorbent at 54 bar) under high pressure environment, which is 9 times higher
than Zeolite 5A,
and 4 times higher than ZIF-8 at the same conditions.
[35] FIGURE 21 shows the results of TEM EDS elemental mapping of A-rNPCs after
H2S
uptake under air treatment. FIG. 21A shows a TEM image of A-rNPC after 112S
uptake. FIG.
21B shows carbon element mapping of A-rNPCs after H2S uptake. FIG. 21C shows
sulfur
elemental mapping of A-rNPCs after H2S uptake.
[36] FIGURE 22 shows a thermogravimetric analysis (TGA) curve of A-rNPCs after
H2S
uptake with exposure to air.
[37] FIGURE 23 shows a summary of the H2S uptake capacity of A-rNPC under
different
conditions, and its comparison to the 1-12S uptake capacity of Maxsorb , a
commercial high
surface area carbonized material.
[38] FIGURE 24 shows comparative data relating to the CO2 uptake capacities of
A-rNPCs and
A-NPCs.
[39] FIGURE 25 shows comparative data relating to the CO2 uptake capacities of
A-NSPCs and
A-SPCs.
[40] FIGURE 26 shows an SEM image of B-NPC (FIG. 26A), a TEM image of B-NPC
(FIG.
26B), a BET isotherm curve of B-NPC, indicating I3-NPC is a microporous
material with a
surface area of 2988 m2/g (FIG. 26C), and a DET size distribution of B-NPC,
showing that the
pore size is from 0.5-5 nm (FIG. 26D).
[41] FIGURE 27 shows CO2 uptake performances of different sorbents, B-NPC and
C-NPC
(charcoal derived N-containing porous carbon) at 25 C.
[42] FIGURE 28 shows CO2 uptake performances of different B-PC prepared by
different bases.
[43] FIGURE 29 shows CO2 uptake performances of different B-NPC prepared from
different
precursors using KOH as base.
8
CA 02901455 2015-08-25
[44] FIGURE 30 shows the thermogravimetric analysis (TGA) curves of B-NPC and
C-NPC
after H2S capture.
1451 FIGURE 31 shows TGA curves of asphalts from different sources and the
removal of
volatile oils between 400 C and 500 C.
DETAILED DESC R I PT! ON
[46] It is to be understood that both the foregoing general description and
the following detailed
description are illustrative and explanatory, and are not restrictive of the
subject matter, as
claimed. In this application, the use of the singular includes the plural, the
word "a" or "an"
means "at least one", and the use of "or" means "and/or", unless specifically
stated otherwise.
Furthermore, the use of the term "including", as well as other forms, such as
"includes" and
"included", is not limiting. Also, terms such as "element" or "component"
respectively
encompass both elements or components comprising one unit and elements or
components that
comprise more than one unit unless specifically stated otherwise.
[47] The section headings used herein are for organizational purposes and are
not to be construed
as limiting the subject matter described. All documents, or portions of
documents, cited in this
application, including, but not limited to, patents, patent applications,
articles, books, and
treatises, are hereby expressly incorporated herein by reference in their
entirety for any purpose.
In the event that one or more of the incorporated literature and similar
materials defines a term in
a manner that contradicts the definition of that term in this application,
this application controls.
[48] Environmental and health concerns have been linked to carbon dioxide
(CO2) and hydrogen
sulfide (H2S) emission sources, such as industrial power plants, refineries
and natural gas wells.
Therefore, efficient CO2 and H2S capture from flue gases or other high
pressure natural gas wells
has been a primary approach in mitigating environmental and health risks. For
instance, aqueous
amine solvents and membrane technologies have been utilized for CO2 capture.
In addition, solid
sorbents such as activated carbon, zeolites and metal organic frameworks have
been utilized as
alternative materials for capturing CO2.
9
0
CA 02901455 2015-08-25
[49] However, many of the aforementioned technologies suffer from numerous
limitations. For
instance, many CO2 and H2S capture technologies that utilize aqueous amine
solutions arc highly
energy inefficient due to the high energy requirements for regeneration (e.g.,
120 C-140 C).
[50] Furthermore, aqueous amines are prone to foaming and are corrosive in
nature; often
components and piping require stainless steel for construction. They also form
non-regenerative,
degradative compounds in the system that need to be periodically removed.
Moreover, with
adsorber columns, regenerative columns, flash tanks, reboilers, and water
treatment systems,
amine systems have a large equipment footprint and are typically not modular
in design, making
these acid gas removal systems costly and unsuitable for many gas capture
applications, such as
offshore use.
[51] Solid CO2 sorbents have shown many advantages over conventional
separation technologies
that utilize aqueous amine solvents. For instance, solid CO2 sorbents have
been shown to capture
CO2 under high pressure. Moreover, many solid CO2 sorbents have lower
regeneration energy
requirements, higher CO2 uptake capacities, selectivity over hydrocarbons, and
ease of handling.
Moreover, solid CO2 sorbents have shown lower heat capacities, faster kinetics
of sorption and
desorption, and high mechanical strength. In addition, solid CO2 sorbents have
been utilized to
capture and release CO2 without significant pressure and temperature swings.
[52] However, a limitation of many solid CO2 sorbents is the cost of
production. Many solid CO2
sorbents are also unable to compress and separate CO2 from the sorbents in an
efficient manner.
Moreover, the H2S sorption capacities of many solid CO2 sorbents have not been
ascertained.
Therefore, a need exists for the development of more effective and affordable
CO2 and H2S
sorbents. A need also exists for more effective methods of utilizing such
sorbents to capture CO2
and I-12S from various environments.
[53] In some , embodiments such as illustrated in FIG. 1, the present
disclosure pertains to
methods of capturing a gas from an environment. In some embodiments, the
method includes
associating the environment with a porous carbon material (step 10) to result
in sorption of gas
components (e.g., CO2, 112S, and combinations thereof) to the porous carbon
material (step 12).
In some embodiments, the methods of the present disclosure also include a step
of releasing the
gas components from the porous carbon material (step 14). In some embodiments,
the methods
1
CA 02901455 2015-08-25
of the present disclosure also include a step of reusing the porous carbon
material after the
release of the gas components (step 16). In some embodiments, the methods of
the present
disclosure also include a step of disposing the released gas components (step
18). In some
embodiments, the porous carbon material includes asphalt derived porous carbon
materials.
[54] As set forth in more detail herein, the gas capture methods and porous
carbon materials of
the present disclosure have numerous embodiments. For instance, various
methods may be
utilized to associate various types of porous carbon materials with various
environments to result
in the capture of various gas components from the environment. Moreover, the
captured gas
components may be released from the porous carbon materials in various
manners.
[55] Environments
[56] The methods of the present disclosure may be utilized to capture gas from
various
environments. In some embodiments, the environment includes, without
limitation, industrial gas
streams, natural gas streams, natural gas wells, industrial gas wells, oil and
gas fields, and
combinations thereof. In some embodiments, the environment is a subsurface oil
and gas field. In
more specific embodiments, the methods of the present disclosure may be
utilized to capture gas
from an environment that contains natural gas, such as an oil well.
[57] In some embodiments, the environment is a pressurized environment. For
instance, in some
embodiments, the environment has a total pressure higher than atmospheric
pressure.
[58] In some embodiments, the environment has a total pressure of about 0.1
bar to about 500
bar. In some embodiments, the environment has a total pressure of about 2.5
bar to about 100
bar. In some embodiments, the environment has a total pressure of about 5 bar
to about 100 bar.
In some embodiments, the environment has a total pressure of about 25 bar to
about 30 bar. In
some embodiments, the environment has a total pressure of about 100 bar to
about 200 bar. In
some embodiments, the environment has a total pressure of about 200 bar to
about 300 bar.
1591 Gas Components
[60] The methods of the present disclosure may be utilized to capture various
gas components
from an environment. For instance, in some embodiments, the captured gas
component includes,
11
CA 02901455 2015-08-25
without limitation, CO2, H2S, and combinations thereof. In some embodiments,
the captured gas
component includes CO2. In some embodiments, the captured gas component
includes H2S. In
some embodiments, the captured gas component includes CO2 and H2S.
161] Association of Porous Carbon Materials with an Environment
[62] Various methods may be utilized to associate porous carbon materials of
the present
disclosure with an environment. In some embodiments, the association occurs by
incubating the
porous carbon materials with the environment (e.g., a pressurized
environment). In some
embodiments, the association of porous carbon materials with an environment
occurs by flowing
the environment through a structure that contains the porous carbon materials.
In some
embodiments, the structure may be a column or a sheet that contains
immobilized porous carbon
materials. In some embodiments, the structure may be a floating bed that
contains porous carbon
materials.
[63] In some embodiments, the porous carbon materials are suspended in a
solvent while being
associated with an environment. In some embodiments, the solvent may include
water or alcohol.
In some embodiments, the porous carbon materials are associated with an
environment in
pelletized form. In some embodiments, the pelletization can be used to assist
flow of the gas
component through the porous carbon materials.
[64] In some embodiments, the associating occurs by placing the porous carbon
material at or
near the environment. In some embodiments, such placement occurs by various
methods that
include, without limitation, adhesion, immobilization, clamping, and
embedding. Additional
methods by which to associate porous carbon materials with an environment can
also be
envisioned.
[65] Gas Sorption to Porous Carbon Materials
[66] The sorption of gas components (e.g., CO2, H2S, and combinations thereof)
to porous
carbon materials of the present disclosure can occur at various environmental
pressures. For
instance, in some embodiments, the sorption of gas components to porous carbon
materials
occurs above atmospheric pressure. In some embodiments, the sorption of gas
components to
porous carbon materials occurs at total pressures ranging from about 0.1 bar
to about 500 bar. In
12
CA 02901455 2015-08-25
some embodiments, the sorption of gas components to porous carbon materials
occurs at total
pressures ranging from about 5 bar to about 500 bar. In some embodiments, the
sorption of gas
components to porous carbon materials occurs at total pressures ranging from
about 5 bar to
about 100 bar. In some embodiments, the sorption of gas components to porous
carbon materials
occurs at total pressures ranging from about 25 bar to about 30 bar. In some
embodiments, the
sorption of gas components to porous carbon materials occurs at total
pressures ranging from
about 100 bar to about 500 bar. In some embodiments, the sorption of gas
components to porous
carbon materials occurs at total pressures ranging from about 100 bar to about
300 bar. In some
embodiments, the sorption of gas components to porous carbon materials occurs
at total
pressures ranging from about 100 bar to about 200 bar. In some embodiments,
the sorption of
gas components to porous carbon materials occurs at between atmospheric
pressure and about
100 bar of total or partial pressure.
[67] The sorption of gas components to porous carbon materials can also occur
at various
temperatures. For instance, in some embodiments, the sorption of gas
components to porous
carbon materials occurs at temperatures that range from about 0 C (e.g., a
sea floor temperature
where a wellhead may reside) to about 100 C (e.g., a temperature where
machinery may reside).
In some embodiments, the sorption of gas components to porous carbon materials
occurs at
ambient temperature (e.g., temperatures ranging from about 20-25 C, such as
23 C). In some
embodiments, the sorption of gas components to porous carbon materials occurs
below ambient
temperature. In some embodiments, the sorption of gas components to porous
carbon materials
occurs above ambient temperature. In some embodiments, the sorption of gas
components to
porous carbon materials occurs without the heating of the porous carbon
materials. In some
embodiments, the sorption of gas components to porous carbon materials occurs
without the
heating of the porous carbon materials or the environment.
[68] Without being bound by theory, it is envisioned that the sorption of gas
components to
porous carbon materials occurs by various molecular interactions between gas
components (e.g.,
CO2 or H2S) and the porous carbon materials. For instance, in some
embodiments, the sorption
of gas components to porous carbon materials occurs by at least one of
absorption, adsorption,
ionic interactions, physisorption, chemisorption, covalent bonding, non-
covalent bonding,
hydrogen bonding, van der Waals interactions, acid-base interactions, and
combinations of such
13
1
CA 02901455 2015-08-25
mechanisms. In some embodiments, the sorption includes an absorption
interaction between gas
components (e.g., CO2 or H2S) in an environment and the porous carbon
materials. In some
embodiments, the sorption includes an ionic interaction between the gas
components in an
environment and the porous carbon materials. In some embodiments, the sorption
includes an
adsorption interaction between the gas components in an environment and the
porous carbon
materials. In some embodiments, the sorption includes a physisorption
interaction between the
gas components in an environment and the porous carbon materials. In some
embodiments, the
sorption includes a chemisorption interaction between the gas components in an
environment and
the porous carbon materials. In some embodiments, the sorption includes a
covalent bonding
interaction between the gas components in an environment and the porous carbon
materials. In
some embodiments, the sorption includes a non-covalent bonding interaction
between the gas
components in an environment and the porous carbon materials. In some
embodiments, the
sorption includes a hydrogen bonding interaction between the gas components in
an environment
and the porous carbon materials. In some embodiments, the sorption includes a
van der Waals
interaction between the gas components in an environment and the porous carbon
materials. In
some embodiments, the sorption includes an acid-base interaction between the
gas components
in an environment and the porous carbon materials. In some embodiments, the
sorption of gas
components to porous carbon materials occurs by adsorption and absorption.
[69] CO, Sorption
[70] In some embodiments, the sorption of gas components to porous carbon
materials includes
the sorption of CO2 to the porous carbon materials. In some embodiments, the
sorption of CO2 to
porous carbon materials occurs at a partial CO2 pressure of about 0.1 bar to
about 100 bar. In
some embodiments, the sorption of CO2 to porous carbon materials occurs at a
partial CO2
pressure of about 5 bar to about 30 bar. In some embodiments, the sorption of
CO2 to porous
carbon materials occurs at a partial CO2 pressure of about 30 bar.
1711 Without being bound by theory, it is envisioned that CO2 sorption may be
facilitated by
various chemical reactions. For instance, in some embodiments, the sorbed CO2
is converted to
14
CA 02901455 2015-08-25
poly (CO2) within the pores of the porous carbon materials. In some
embodiments, the poly
(CO2) comprises the following formula: ¨ (0-C (-0))¨, where n is equal to or
greater than 2. In
some embodiments, n is between 2 to 10,000. In some embodiments, the formed
poly(CO2) may
be further stabilized by van der Waals interactions with the carbon surfaces
in the pores of the
carbon materials. In some embodiments, the formed poly(CO2) may be in solid
form. In some
embodiments, the poly(CO2) matrix can be formed in a layered structure where
there is a stacked
layering of the CO2 where the CO2 molecules have restricted tumbling and
rotations due to an
ordered stacked arrangement on the surface.
[72] In some embodiments, the sorbed CO2 may be converted to a matrix of CO2
within the
pores of the porous carbon materials. In some embodiments, the matrix of CO2
may be in the
form of a matrix of ordered CO2.
[73] In some embodiments, the sorption of CO2 to the porous carbon materials
occurs
selectively. For instance, in some embodiments, the sorption of CO2 to the
porous carbon
materials occurs selectively over hydrocarbons in the environment (e.g.,
ethane, propane, butane,
pentane, methane, and combinations thereof). In further embodiments, the
molecular ratio of
sorbed CO2 to sorbed hydrocarbons in the porous carbon materials is greater
than about 2. In
additional embodiments, the molecular ratio of sorbed CO2 to sorbed
hydrocarbons in the porous
carbon materials ranges from about 2 to about 10. In additional embodiments,
the molecular ratio
of sorbed CO2 to sorbed hydrocarbons in the porous carbon materials is about
8.
[74] In more specific embodiments, the sorption of CO2 to porous carbon
materials occurs
selectively over the CH4 in the environment. In further embodiments, the
molecular ratio of
sorbed CO2 to sorbed CH4 (nCO2 / nCII4) in the porous carbon materials is
greater than about 2.
In additional embodiments, nCO21nCH4 in the porous carbon materials ranges
from about 2 to
about 20. In some embodiments, nCO2/nCH4 in the porous carbon materials ranges
from about 2
to about 10. In more specific embodiments, nCO2/nCH4 in the porous carbon
materials is about
20 at 30 bar.
[75] In some embodiments, sorption of CO2 to porous carbon materials occurs
selectively
through poly(CO2) formation within the pores of the porous carbon materials.
Without being
bound by theory, it is envisioned that poly(CO2) formation within the pores of
the porous carbon
CA 02901455 2015-08-25
materials can displace other gas components associated with the porous carbon
materials,
including any physisorbed gas components and hydrocarbons (e.g., methane,
propane, and
butane). Without being bound by further theory, it is also envisioned that the
displacement of
other gas components from the porous carbon materials creates a continual CO2
selectivity that
far exceeds various CO2 selectively ranges, including the CO2 selectivity
ranges noted above.
[76] In some embodiments, the covalent or stacked dipolar nature of poly(CO2)
within the pores
of the porous carbon materials can be 100 times stronger than that of other
physisorbed entities,
including physisorbed gas components within the pores of the porous carbon
materials.
Therefore, such strong covalent bonds or dipolar bonds can contribute to the
displacement of the
physisorbed gas components (e.g., methane, propane and butane). The dipolar
bonds are
arranged such that the oxygen of one CO2 is donating into a lone pair electron
density in the
carbon atom of a neighboring CO2. This pattern can repeat itself in a 1-
dimensional, 2-
dimensional to 3-dimensional arrangement.
[77] I-12S Sorption
[78] In some embodiments, the sorption of gas components to porous carbon
materials includes
the sorption of H2S to the porous carbon materials. In some embodiments, the
sorption of FI2S to
porous carbon materials occurs at a partial H2S pressure of about 0.1 bar to
about 100 bar. In
some embodiments, the sorption of H2S to porous carbon materials occurs at a
partial H2S
pressure of about 5 bar to about 30 bar. In some embodiments, the sorption of
H2S to porous
carbon materials occurs at a partial H2S pressure of about 30 bar.
[79] Without being bound by theory, it is envisioned that H2S sorption may be
facilitated by
various chemical reactions. For instance, in some embodiments, sorbed H2S may
be converted
within the pores of the porous carbon materials to at least one of elemental
sulfur (S), sulfur
dioxide (SO2), sulfuric acid (H2SO4), hydridosulfide (HS), sulfide (S2) and
combinations
thereof. In some embodiments, the aforementioned conversion can be facilitated
by the presence
of oxygen. For instance, in some embodiments, the introduction of small
amounts of oxygen into
a system containing porous carbon materials can facilitate the conversion of
H2S to elemental
sulfur. In some embodiments, the oxygen can be introduced either continuously
or periodically.
In some embodiments, the oxygen can be introduced from air.
16
CA 02901455 2015-08-25
[80] In some embodiments, the captured H2S is converted by catalytic oxidation
to elemental
sulfur at ambient temperature. Thereafter, further oxidation to SO2 and H2SO4
occurs at higher
temperatures.
[81] In some embodiments, nitrogen groups of porous carbon materials may
facilitate the
conversion of H2S to elemental sulfur. For instance, in some embodiments
illustrated in the
schemes in FIG. 2, nitrogen functional groups on porous carbon materials may
facilitate the
dissociation of H2S to HS". In some embodiments, the nitrogen functional
groups may also
facilitate the formation of chemisorbed oxygen species (Seredych, M.; Bandosz,
T. J. J. Phys.
Chem. C 2008, 112, 4704-4711).
[82] In some embodiments, the porous carbon material becomes impregnated with
the sulfur
derived from captured H2S to form sulfur-impregnated porous carbon materials.
In some
embodiments, the formation of sulfur-impregnated porous carbon materials may
be facilitated by
heating. In some embodiments, the heating occurs at temperatures higher than
H2S capture
temperatures. In some embodiments, the heating occurs in the absence of
oxygen. In some
embodiments, the sulfur impregnated porous carbon material can be used to
efficiently capture
CO2 by the aforementioned methods.
[83] In some embodiments, the sorption of H2S to porous carbon materials
occurs in intact form.
In some embodiments, the sorption of H2S to porous carbon materials in intact
form occurs in the
absence of oxygen.
184] CO, and H2S Sorption
1851 In some embodiments, the sorption of gas components to porous carbon
materials includes
the sorption of both H2S and CO2 to the porous carbon materials. In some
embodiments, the
sorption of I-12S and CO2 to the porous carbon material occurs at the same
time.
[86] In some embodiments, the sorption of CO2 to the porous carbon material
occurs before the
sorption of H2S to the porous carbon material. For instance, in some
embodiments, a gas
containing CO2 and II2S flows through a structure that contains porous carbon
materials (e.g.,
trapping cartridges). CO2 is first captured from the gas as the gas flows
through the structure.
Thereafter, H2S is captured from the gas as the gas continues to flow through
the structure.
17
CA 02901455 2015-08-25
[87] In some embodiments, the sorption of H2S to the porous carbon material
occurs before the
sorption of CO2 to the porous carbon material. For instance, in some
embodiments, a gas
containing CO2 and H2S flows through a structure that contains porous carbon
materials (e.g.,
trapping cartridges). H2S is first captured from the gas as the gas flows
through the structure.
Thereafter, CO2 is captured from the gas as the gas continues to flow through
the structure.
1881 In some embodiments, the porous carbon materials that capture 1-12S from
the gas include
nitrogen-containing porous carbon materials, as described in more detail
herein. In some
embodiments, the porous carbon materials that capture CO2 from the gas include
sulfur-
containing porous carbon materials that are also described in more detail
herein.
[89] Release of Captured Gas
[90] In some embodiments, the methods of the present disclosure also include a
step of releasing
captured gas components from porous carbon materials. Various methods may be
utilized to
release captured gas components from porous carbon materials. For instance, in
some
embodiments, the releasing occurs by decreasing the pressure of the
environment. In some
embodiments, the pressure of the environment is reduced to atmospheric
pressure or below
atmospheric pressure. In some embodiments, the releasing occurs by placing the
porous carbon
material in a second environment that has a lower pressure than the
environment where gas
capture occurred. In some embodiments, the second environment may be at or
below
atmospheric pressure. In some embodiments, the releasing occurs spontaneously
as the
environmental pressure decreases. This is often referred to as pressure swing
sorption or a
pressure swing separation process.
[91] The release of captured gas components from porous carbon materials can
occur at various
pressures. For instance, in some embodiments, the release occurs at or below
atmospheric
pressure. In some embodiments, the release occurs at total pressures ranging
from about 0 bar to
about 100 bar. In some embodiments, the release occurs at total pressures
ranging from about 0.1
bar to about 50 bar. In some embodiments, the release occurs at total
pressures ranging from
about 0.1 bar to about 30 bar. In some embodiments, the release occurs at
total pressures ranging
from about 0.1 bar to about 10 bar. In some embodiments, the release occurs at
total pressures
ranging from about 0.1 bar to about atmospheric pressure.
18
CA 02901455 2015-08-25
1921 The release of captured gas components from porous carbon materials can
also occur at
various temperatures. In some embodiments, the releasing occurs at ambient
temperature. In
some embodiments, the releasing occurs at the same temperature at which gas
sorption occurred.
In some embodiments, the releasing occurs without heating the porous carbon
materials. In
some embodiments, the releasing occurs without heating the porous carbon
materials or the
environment. Therefore, in some embodiments, a temperature swing is not
required to release
captured gas components from porous carbon materials.
[93] In some embodiments, the releasing occurs at temperatures ranging from
about 30 C to
about 200 C. In some embodiments, the releasing is facilitated by also
lowering the pressure.
[94] In some embodiments, the releasing occurs by heating the porous carbon
materials. In some
embodiments, the releasing is enhanced by the addition of heat to the porous
carbon material or
to the environment. For instance, in some embodiments, the releasing occurs by
heating the
porous carbon materials to temperatures between about 50 C to about 200 C.
In some
embodiments, the releasing occurs by heating the porous carbon materials to
temperatures
between about 75 C to about 125 C. In some embodiments, the releasing occurs
by heating the
porous carbon materials to temperatures ranging from about 50 C to about 100
C. In some
embodiments, the releasing occurs by heating the porous carbon materials to a
temperature of
about 90 C.
[95] In some embodiments, heat for release of gas components from porous
carbon materials can
be supplied from various sources. For instance, in some embodiments, the heat
for the release of
gas components from a porous carbon material-containing vessel can be provided
by an adjacent
vessel whose heat is being generated during a gas sorption step.
[96] In some embodiments, the release of captured gas components from an
environment
includes the release of captured CO2 from porous carbon materials. Without
being bound by
theory, it is envisioned that the release of captured CO2 from porous carbon
materials can occur
by various mechanisms. For instance, in some embodiments, the release of
captured CO2 can
occur through a depolymerization of the formed poly(CO2) within the pores of
the porous carbon
materials. In some embodiments, the depolymerization can be facilitated by a
decrease in
environmental pressure. In some embodiments, the releasing of the CO2 occurs
by decreasing the
19
CA 02901455 2015-08-25
pressure of the environment or placing the porous carbon material in a second
environment that
has a lower pressure than the environment where CO2 capture occurred.
[97] In some embodiments, the release of captured gas components from an
environment
includes the release of captured H2S from porous carbon materials. In some
embodiments, the
captured H2S is released in intact form.
[98] In some embodiments, H2S is released from porous carbon materials by
heating the porous
carbon materials. In some embodiments, 112S is released from porous carbon
materials by
heating the porous carbon materials to temperatures that range from about 50
C to about 200 C.
In some embodiments, H2S is released from the porous carbon materials by
heating the porous
carbon materials to temperatures between about 75 C to about 125 C. In some
embodiments,
H2S is released from the porous carbon materials by heating the porous carbon
materials to
temperatures between about 50 C to about 100 C. In some embodiments, H2S is
released from
the porous carbon materials by heating the porous carbon materials to a
temperature of about 90
C.
[99] In some embodiments, the release of captured H2S can occur through
conversion of H2S to
at least one of elemental sulfur (S), sulfur dioxide (SO2), sulfuric acid
(H2SO4), hydridosulfide
(HS), sulfide (S2) and combinations thereof. In some embodiments, elemental
sulfur is retained
on the porous carbon material to form sulfur-impregnated porous carbon
materials. In some
embodiments, the sulfur-containing porous carbon material can be discarded
through
incineration or burial. In some embodiments, the sulfur-impregnated porous
carbon material can
be used for the reversible capture of CO2. In some embodiments, the sulfur-
impregnated porous
carbon material can be heated to high temperature of 400-900 C to make a
sulfur-impregnated
porous carbon used for the reversible capture of CO2.
11001 In some embodiments, the release of captured gas components can occur in
a sequential
manner. For instance, in some embodiments where the sorbed gas components
include both CO2
and H2S, the releasing of the CO2 occurs by decreasing the pressure of the
environment or
placing the porous carbon material in a second environment that has a lower
pressure than the
environment where CO2 capture occurred. In some embodiments, the releasing of
the H2S occurs
by heating the porous carbon material (e.g., at temperatures ranging from
about 50 C to about
0
CA 02901455 2015-08-25
100 C). In some embodiments, the releasing of the CO2 occurs before the
releasing of the H2S.
In some embodiments, the releasing of the H2S occurs before the releasing of
the CO2. In some
embodiments, the releasing of H2S occurs in an environment that lacks oxygen.
11011 Disposal of the Released gas
[102] In some embodiments, the methods of the present disclosure also include
a step of
disposing the released gas components. For instance, in some embodiments, the
released gas
components can be off-loaded into a container. In some embodiments, the
released gas
components can be pumped downhole for long-term storage. In some embodiments,
the released
gas components can be vented to the atmosphere. In some embodiments, the
released gas
components include, without limitation, CO2, H2S, SO2, and combinations
thereof.
[103] Reuse of the Porous Carbon Material
[104] In some embodiments, the methods of the present disclosure also include
a step of reusing
the porous carbon materials after gas component release to capture more gas
components from
an environment. In some embodiments, the porous carbon materials of the
present disclosure
may be reused over 100 times without substantially affecting their gas
sorption capacities. In
some embodiments, the porous carbon materials of the present disclosure may be
reused over
1000 times without substantially affecting their gas sorption capacities. In
some embodiments,
the porous carbon materials of the present disclosure may be reused over
10,000 times without
substantially affecting their gas sorption capacities.
[105] In some embodiments, the porous carbon materials of the present
disclosure may retain
100 wt% of their CO2 or I I2S sorption capacities after being used multiple
times (e.g., 100 times,
1,000 times or 10,000 times). In some embodiments, the porous carbon materials
of the present
disclosure may retain at least 98 wt% of their CO2 or I I2S sorption
capacities after being used
multiple times (e.g., 100 times, 1,000 times or 10,000 times). In some
embodiments, the porous
carbon materials of the present disclosure may retain at least 95 wt% of their
CO2 or H2S
sorption capacities after being used multiple times (e.g., 100 times, 1,000
times or 10,000 times).
In some embodiments, the porous carbon materials of the present disclosure may
retain at least
90 wt% of their CO2 or H2S sorption capacities after being used multiple times
(e.g., 100 times,
21
CA 02901455 2015-08-25
1,000 times or 10,000 times). In some embodiments, the porous carbon materials
of the present
disclosure may retain at least 80 wt% of their CO2 or H2S sorption capacities
after being used
multiple times (e.g., 100 times, 1,000 times or 10,000 times).
[106] Porous Carbon Materials
[107] Various porous carbon materials may be utilized to capture gas from an
environment. In
some embodiments, the present disclosure pertains to the porous carbon
materials that are
utilized to capture gas from an environment.
[108] Carbon sources
[109] The porous carbon materials of the present disclosure may be derived
from various carbon
sources. For instance, in some embodiments, the porous carbon material
includes, without
limitation, protein-derived porous carbon materials, carbohydrate-derived
porous carbon
materials, cotton-derived porous carbon materials, fat-derived porous carbon
materials, waste-
derived porous carbon materials, asphalt-derived porous carbon materials, coal-
derived porous
carbon materials, coke-derived porous carbon materials, asphaltene-derived
porous carbon
materials, oil product-derived porous carbon materials, bitumen-derived porous
carbon materials,
tar-derived porous carbon materials, pitch-derived porous carbon materials,
anthracite-derived
porous carbon materials, melamine-derived porous carbon materials, biochar-
derived porous
carbon, wood-derived porous carbon and combinations thereof.
[110] In some embodiments, the porous carbon materials of the present
disclosure include
asphalt-derived porous carbon materials. In some embodiments, the porous
carbon materials of
the present disclosure include coal-derived porous carbon materials. In some
embodiments, the
coal source includes, without limitation, bituminous coal, anthracitic coal,
brown coal, and
combinations thereof.
[111] In some embodiments, the porous carbon materials of the present
disclosure include
protein-derived porous carbon materials. In some embodiments, the protein
source includes,
22
CA 02901455 2015-08-25
without limitation, whey protein, rice protein, animal protein, plant protein,
and combinations
thereof.
[112] In some embodiments, the porous carbon materials of the present
disclosure include oil
product-derived porous carbon materials. In some embodiments, the oil products
include,
without limitation, petroleum oil, plant oil, and combinations thereof.
[113] In some embodiments, the porous carbon materials of the present
disclosure include waste
derived porous carbon materials. In some embodiments, the waste can include,
without
limitation, human waste, animal waste, waste derived from municipality
sources, and
combinations thereof
[114] The porous carbon materials of the present disclosure may also be in
various states. For
instance, in some embodiments, the porous carbon material is carbonized. In
some embodiments,
the porous carbon material is reduced. In some embodiments, the porous carbon
material is
vulcanized.
[115] Nucleophilic Moieties
[116] In some embodiments, the porous carbon materials of the present
disclosure include a
plurality of nucleophilic moieties. In some embodiments, the porous carbon
materials of the
present disclosure may contain various arrangements of nucleophilic moieties.
In some
embodiments, the nucleophilic moieties are part of the porous carbon material.
In some
embodiments, the nucleophilic moieties are embedded within the porous carbon
materials. In
some embodiments, the nucleophilic moieties are homogcnously distributed
throughout the
porous carbon material framework. In some embodiments, the nucleophilic
moieties are
embedded within the plurality of the pores of the porous carbon materials.
[117] In some embodiments, the nucleophilic moieties include, without
limitation, primary
nucleophiles, secondary nucleophiles, tertiary nucleophiles and combinations
thereof. In some
embodiments, the nucleophilic moieties include, without limitation, oxygen-
containing moieties,
sulfur-containing moieties, metal-containing moieties, metal oxide-containing
moieties, metal
sulfide-containing moieties, nitrogen-containing moieties, phosphorous-
containing moieties, and
combinations thereof.
23
CA 02901455 2015-08-25
[118] In more specific embodiments, the nucleophilic moieties include
phosphorous-containing
moieties. In some embodiments, the phosphorous containing moieties include,
without
limitation, phosphines, phosphites, phosphine oxides, and combinations
thereof.
[119] In some embodiments, the nueleophilie moieties include nitrogen-
containing moieties. In
some embodiments, the nitrogen-containing moieties include, without
limitation, primary
amines, secondary amines, tertiary amines, nitrogen oxides, pyridinic
nitrogens, pyrrolic
nitrogens, graphitic nitrogens, and combinations thereof. In more specific
embodiments, the
nitrogen containing moieties include nitrogen oxides, such as N-oxides.
[120] In some embodiments, the nitrogen-containing moieties include from about
1 wt% to about
15 wt% by weight of the porous carbon material. In some embodiments, the
nitrogen-containing
moieties include from about 2 wt% to about 11 wt% by weight of the porous
carbon material. In
some embodiments, the nitrogen-containing moieties include from about 5 wt% to
about 9 wt%
by weight of the porous carbon material. In some embodiments, the nitrogen-
containing moieties
include from about 8 wt% to about 11 wt% by weight of the porous carbon
material. In some
embodiments, the nitrogen-containing moieties include about 9 wt% by weight of
the porous
carbon material.
[121] In some embodiments, the nucleophilic moieties include sulfur-containing
moieties. In
some embodiments, the sulfur-containing moieties include, without limitation,
primary sulfurs,
secondary sulfurs, sulfur oxides, and combinations thereof.
[122] In some embodiments, the nucleophilic moieties include nitrogen-
containing moieties and
sulfur-containing moieties. In some embodiments, the nitrogen-containing
moieties and sulfur-
containing moieties induce CO2 capture by poly(CO2) formation. In some
embodiments, the
nitrogen-containing moieties induce I-I2S capture by facilitating oxidation of
H2S.
[123] Surface Areas
11241 The porous carbon materials of the present disclosure may have various
surface areas. For
instance, in some embodiments, the porous carbon materials of the present
disclosure have
surface areas that range from about 1,000 m2/g to about 4,500 m2/g. In some
embodiments, the
porous carbon materials of the present disclosure have surface areas that
range from about 2,500
24
CA 02901455 2015-08-25
m2/g to about 4,500 m2/g. In some embodiments, the porous carbon materials of
the present
disclosure have surface areas that range from about 2,500 m2/g to about 4,200
m2/g. In more
specific embodiments, the porous carbon materials of the present disclosure
have surface areas
that include at least one of 2,200 m2 g-1, 2,300 m2/g, 2,600 m2/g, 2,800 m2/g,
2,900 m2 g-1 or
4,200 m2 g-1.
[125] Porosities
[126] In some embodiments, the porous carbon materials of the present
disclosure include a
plurality of pores. In addition, the porous carbon materials of the present
disclosure may have
various porosities. For instance, in some embodiments, the pores in the porous
carbon materials
include diameters between about 1 nanometer to about 5 micrometers. In some
embodiments, the
pores include macropores with diameters of at least about 50 nm. In some
embodiments, the
pores include macropores with diameters between about 50 nanometers to about 3
micrometers.
In some embodiments, the pores include macropores with diameters between about
500
nanometers to about 2 micrometers. In some embodiments, the pores include
mesopores with
diameters of less than 50 nm and larger than about 2 nm. In some embodiments,
the pores
include micropores with diameters of less than about 2 nm.
[127] In some embodiments, the pores include diameters that range from about 1
nm to about 10
nm. In some embodiments, the pores include diameters that range from about 1
nm to about 3
nm. In some embodiments, the pores include diameters that range from about 5
nm to about 100
nm. In some embodiments, the pores include diameters that are about 3 nm or
less. In some
embodiments, the majority of the pores in the porous carbon material include
diameters that are
about 3 nm or less.
[128] In some embodiments, the porous carbon materials have a uniform
distribution of pore
sizes. In some embodiments, the uniform pore sizes are about 1.3 nm in
diameter.
[129] The pores of the porous carbon materials of the present disclosure may
also have various
volumes. For instance, in some embodiments, the pores in the porous carbon
materials have
CA 02901455 2015-08-25
volumes ranging from about 1 cm3/g to about 10 cm3/g. In some embodiments, the
pores in the
porous carbon materials have volumes ranging from about 1 cm3/g to about 3
cm3/g. In some
embodiments, the pores in the porous carbon materials have volumes ranging
from about 1 cm3/g
to about 1.5 cm3/g. In more specific embodiments, the plurality of pores in
the porous carbon
materials have volumes of about 1.1 cm3/g, about 1.2 cm3/g, or about 1.4
cm3/g.
1130] Densities
[131] The porous carbon materials of the present disclosure may also have
various densities. For
instance, in some embodiments, the porous carbon materials of the present
disclosure have
densities that range from about 0.3 g/cm3 to about 10 g/cm3. In some
embodiments, the porous
carbon materials of the present disclosure have densities that range from
about 0.3 g/cm3 to about
4 g/cm3. In some embodiments, the porous carbon materials of the present
disclosure have
densities that range from about 1 g/cm3 to about 3 g/cm3. In some embodiments,
the porous
carbon materials of the present disclosure have densities that range from
about 1 g/cm3 to about
2.5 g/cm3. In some embodiments, the porous carbon materials of the present
disclosure have
densities that range from about 2 g/cm3 to about 3 g/cm3. In more specific
embodiments, the
porous carbon materials of the present disclosure have densities of 1.8 g/cm3,
2 g/cm3, or 2.2
g/cm3.
[132] CO2 Sorption Capacities
11331 The porous carbon materials of the present disclosure may also have
various sorption
capacities. For instance, in some embodiments, the porous carbon materials of
the present
disclosure have a CO2 sorption capacity (also referred to as CO2 uptake) that
ranges from about
wt% to about 150 wt% of the porous carbon material weight. In some
embodiments, the
porous carbon materials of the present disclosure have a CO2 sorption capacity
of about 50 wt%
to about 150 wt% of the porous carbon material weight. In some embodiments,
the porous
carbon materials of the present disclosure have a CO2 sorption capacity of
about 50 wt% to about
100 wt% of the porous carbon material weight. In some embodiments, the porous
carbon
materials of the present disclosure have a CO2 sorption capacity of about 50
wt% to about 200
wt% of the porous carbon material weight. In some embodiments, the porous
carbon materials
26
1
CA 02901455 2015-08-25
of the present disclosure have a CO2 sorption capacity of about 100 wt% to
about 150 wt% of the
porous carbon material weight. In more specific embodiments, the porous carbon
materials of the
present disclosure have a CO2 sorption capacity of about 120 wt% to about 130
wt% of the
porous carbon material weight.
[134] In further embodiments, the porous carbon materials of the present
disclosure have a CO2
sorption capacity of about 0.5 g to about 2 g of CO2 per 1 g of porous carbon
material. In some
embodiments, the porous carbon materials of the present disclosure have a CO2
sorption capacity
of about 1 g to about 2 g of CO2 per I g of porous carbon material. In some
embodiments, the
porous carbon materials of the present disclosure have a CO2 sorption capacity
of about 1.2 g to
about 1.3 g of CO2 per 1 g of porous carbon material.
[135] In further embodiments, the porous carbon materials of the present
disclosure have a CO2
sorption capacity of about 0.6 g to about 2.0 g of CO2 per 1 g of porous
carbon material. In some
embodiments, the porous carbon materials of the present disclosure have a CO2
sorption capacity
of about 1 g to about 1.2 g of CO2 per 1 g of porous carbon material. In some
embodiments, the
porous carbon materials of the present disclosure have a CO2 sorption capacity
of about 1.2 g of
CO2 per 1 g of porous carbon material. In some embodiments, the porous carbon
materials of
the present disclosure have a CO2 sorption capacity of about 0.92 g of CO2 per
1 g of porous
carbon material. In some embodiments, the porous carbon materials of the
present disclosure
have a CO2 sorption capacity of about 0.92 g of CO2 per 1 g of porous carbon
material at a CO2
pressure or partial pressure of about 30 bar.
[136] H2S Sorption Capacities
[137] The porous carbon materials of the present disclosure may also have
various H2S sorption
capacities. For instance, in some embodiments, the porous carbon materials of
the present
disclosure have a I-12S sorption capacity that ranges from about 10 wt% to
about 300 wt % of the
porous carbon material weight. In some embodiments, the porous carbon
materials of the present
disclosure have a H2S sorption capacity of about 50 wt% to about 300 wt% of
the porous carbon
material weight. In some embodiments, the porous carbon materials of the
present disclosure
have a H2S sorption capacity of about 50 wt% to about 250 wt% of the porous
carbon material
weight. In some embodiments, the porous carbon materials of the present
disclosure have a H2S
27
CA 02901455 2015-08-25
sorption capacity of about 100 wt% to about 250 wt% of the porous carbon
material weight. In
more specific embodiments, the porous carbon materials of the present
disclosure have a H2S
sorption capacity of about 100 wt% to about 150 wt% of the porous carbon
material weight. In
some embodiments, Applicant has been able to achieve uptake of 205 wt% H2S
sorption capacity
using the asphalt doped porous carbon materials of the present disclosure.
[138] In further embodiments, the porous carbon materials of the present
disclosure have a H2S
sorption capacity of about 0.5 g to about 3 g of sulfur from H2S per 1 g of
porous carbon
material. In some embodiments, the porous carbon materials of the present
disclosure have a H2S
sorption capacity of about 0.5 g to about 2.5 g of sulfur from H2S per 1 g of
porous carbon
material. In some embodiments, the porous carbon materials of the present
disclosure have a H2S
sorption capacity of about 1 g to about 2.5 g of sulfur from H2S per 1 g of
porous carbon
material. In some embodiments, the porous carbon materials of the present
disclosure have a 1-12S
sorption capacity of about 1 g to about 1.5 g of sulfur from I-12S per 1 g of
porous carbon
material.
[1391 Physical States
[140] The porous carbon materials of the present disclosure may be in various
states. For
instance, in some embodiments, the porous carbon materials of the present
disclosure may be in
a solid state. In some embodiments, the porous carbon materials of the present
disclosure may be
in a gaseous state. In some embodiments, the porous carbon materials of the
present disclosure
may be in a liquid state.
[141] Methods of forming porous carbon materials
1142] In some embodiments, the present disclosure pertains to methods of
forming the porous
carbon materials of the present disclosure. In some embodiments, methods
include carbonizing a
carbon source to form porous carbon materials and may also include a step of
doping the carbon
source. In some embodiments, the methods of the present disclosure also
include a step of
vulcanizing the carbon source. In some embodiments, the methods of the present
disclosure also
include a step of reducing the formed porous carbon material. In some
embodiments, by pre-
28
CA 02901455 2015-08-25
treating the carbon source prior to carbonization, no further treatment of the
porous carbon is
necessary,
[143] As set forth in more detail herein, various methods may be utilized to
carbonize various
types of carbon sources. In addition, various methods may be utilized to dope
and vulcanize the
carbon sources. Likewise, various methods may be utilized to reduce the formed
porous carbon
materials.
[144] Carbon Sources
[145] Various carbon sources may be utilized to form porous carbon materials.
Suitable carbon
sources were described previously. In some embodiments, the carbon sources
include, without
limitation, protein, carbohydrates, cotton, fat, waste, asphalt, coal, coke,
asphaltene, oil products,
bitumen, tar, pitch, anthracite, melamine, and combinations thereof
[146] In some embodiments, the carbon source includes asphalt. In some
embodiments, the
carbon source includes coal. In some embodiments, the coal source includes,
without limitation,
bituminous coal, anthracitic coal, brown coal, and combinations thereof. In
some embodiments,
the carbon source includes protein. In some embodiments, the protein source
includes, without
limitation, whey protein, rice protein, animal protein, plant protein, and
combinations thereof
[147] In some embodiments, the carbon source includes oil products. In some
embodiments, the
oil products include, without limitation, petroleum oil, plant oil, and
combinations thereof.
11481 Carbonizing
[149] In the present disclosure, carbonization generally refers to processes
or treatments that
convert a carbon source (e.g., a non-porous carbon source) to a porous carbon
material. Various
methods and conditions may be utilized to carbonize carbon sources.
[150] For instance, in some embodiments, the carbonizing occurs in the absence
of a solvent. In
some embodiments, the carbonizing occurs in the presence of a solvent.
[151] In some embodiments, the carbonizing occurs by exposing the carbon
source to a
carbonizing agent. In some embodiments, the carbonizing agent includes metal
hydroxides or
29
CA 02901455 2015-08-25
metal oxides. In some embodiments, the carbonizing agent includes, without
limitation,
potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (Li0H),
cesium
hydroxide (Cs0H), magnesium hydroxide (Mg(OH)2), calcium hydroxide (Ca(O1-
1)2), and
combinations thereof. In some embodiments, the carbonizing agent includes
potassium
hydroxide (KOH). In some embodiments, the carbonizing agent can be a metal
oxide. In some
embodiments, the metal oxide includes, without limitation, calcium oxide
(CaO), magnesium
oxide (MgO), and combinations thereof. In some embodiments, the weight ratio
of the carbon
source to the carbonizing agent varies from about 1:1 to about 1:5. In some
embodiments, the
weight ratio of the carbon source to the carbonizing agent is about 1:4.
[152] In some embodiments, the carbonizing occurs by grinding the carbon
source in the
presence of a carbonizing agent. In some embodiments, the grinding occurs in a
mortar. In some
embodiments, the grinding includes ball milling. In some embodiments, the
grinding results in
the formation of a homogenous solid powder.
[153] In some embodiments, the carbon source and the carbonizing agent can be
mixed in a
solvent. In some embodiments, the solvent is evaporated after mixing. In some
embodiments, the
evaporation is followed by the carbonization of the carbon source at elevated
temperature. In
some embodiments, the carbon source is the solvent, and the carbonizing agent
is added prior to
carbonization at elevated temperatures.
[154] In some embodiments, the carbonizing occurs by heating the carbon source
at temperatures
ranging from about 200 C to about 1000 C. In some embodiments, the heating
occurs at
temperatures greater than 500 C. In some embodiments, the heating occurs at
temperatures of
about 500 C to about 1000 C. In some embodiments, the heating occurs at
temperatures of
about 600 C to about 900 C. In some embodiments, the carbon source is pre-
treated at a
temperature between 300 C to 400 C to remove volatile oils from the carbon
source. For
instance, Figure 31 shows the successful removal of volatile oils by pre-
treatment, as measured
using TGA.
1155] In some embodiments, it is also possible to separate these oils from the
carbon source at
lower temperatures using a reduced pressure atmosphere. After the removal of
volatiles, the
carbon source can subsequently be homogenized with potassium hydroxide and
then heated to
CA 02901455 2015-08-25
temperatures greater than 600 C. For example, by pre-treating asphalt at 400
C prior to
carbonizing with KOH, the resultant porous carbon has very high CO2 uptake,
matching or
exceeding the performance of A-NPC and A-rNPC. Furthermore, pre-treated
asphalt-derived
porous carbons show an increase in CO2 selectivity. No additives are required
to achieve the
aforementioned increased CO2 uptake and selectivity.
1156] In some embodiments, the carbonizing occurs in an inert atmosphere. In
some
embodiments, the inert atmosphere includes a steady flow of an inert gas, such
as argon.
[157] Doping
[158] In some embodiments, the methods of the present disclosure also include
a step of doping
a carbon source with a dopant. In some embodiments, the dopant includes,
without limitation,
nitrogen-containing dopants, sulfur-containing dopants, heteroatom-containing
dopants, oxygen-
containing dopants, sulfur-containing dopants, metal-containing dopants, metal
oxide-containing
dopants, metal sulfide-containing dopants, phosphorous-containing dopants, and
combinations
thereof
11591 In some embodiments, the dopant includes nitrogen-containing dopants. In
some
embodiments, the nitrogen-containing dopants include, without limitation,
primary amines,
secondary amines, tertiary amines, nitrogen oxides, pyridinic nitrogens,
pyrrolic nitrogens,
graphitic nitrogens, and combinations thereof. In some embodiments, the
nitrogen-containing
dopant includes NH3.
11601 In some embodiments, the dopant includes sulfur-containing dopants. In
some
embodiments, the sulfur-containing dopants include, without limitation,
primary sulfurs,
secondary sulfurs, sulfur oxides, and combinations thereof. In some
embodiments, the sulfur-
containing dopants include H2 S.
11611 In some embodiments, the dopants include monomers, such as nitrogen-
containing
monomers. In some embodiments, the monomers are subsequently polymerized.
[162] Doping can occur at various temperatures. For instance, in some
embodiments, the doping
occurs at temperatures ranging from about 200 C to about 800 C. In some
embodiments, the
31
CA 02901455 2015-08-25
doping occurs at temperatures ranging from about 600 C to about 700 C. In
some
embodiments, the doping occurs at about 650 C to about 700 C.
[163] Various amounts of dopants may be utilized. For instance, in some
embodiments, the
weight ratio of the dopant to the carbon source varies from about 0.2:1 to
about 1:1. In some
embodiments, the weight ratio of the dopant to the carbon source is about 1:1.
[164] Vulcanization
[165] In some embodiments, the methods of the present disclosure also include
a step of
vulcanizing the carbon source. In some embodiments, the vulcanizing includes
exposing the
carbon source to a vulcanizing agent. In some embodiments, the vulcanizing
agent includes,
without limitation, sulfur-based agents, peroxides, urethane cross-linkers,
metallic oxides,
acetoxysilane, and combinations thereof. In some embodiments, the vulcanizing
agent includes,
without limitation, tetramethyldithiuram, 2,2'-dithiobis(benzothiazole), and
combinations
thereof.
[166] Various amounts of vulcanizing agents may be utilized. For instance, in
some
embodiments, the weight ratio of the vulcanization agent to the carbon source
varies from about
wt% to about 200 wt% relative to the carbon source.
[167] Reduction
[168] In some embodiments, the methods of the present disclosure include a
step of reducing the
formed porous carbon material. In some embodiments, the reducing occurs by
exposing the
formed porous carbon material to a reducing agent. In some embodiments, the
reducing agent
includes, without limitation, H2, NaBH4, hydrazine, and combinations thereof.
In some
embodiments, the reducing agent includes H2.
[169] The methods of the present disclosure may be utilized to make bulk
quantities of porous
carbon materials. For instance, in some embodiments, the methods of the
present disclosure can
be utilized to make porous carbon materials in quantities greater than about I
g. In some
embodiments, the methods of the present disclosure can be utilized to make
porous carbon
materials in quantities greater than about 1 kg. In some embodiments, the
methods of the present
32
CA 02901455 2015-08-25
disclosure can be utilized to make porous carbon materials in quantities
greater than about 1000
kg.
[170] In some embodiments, the porous carbon materials of the present
disclosure arc produced
from a high fixed carbon content precursor that includes, without limitation,
biochar, hydrochar,
coal, lignite, biomass, organic substances containing heteroatoms such as
nitrogen or sulfur, and
combinations thereof. In some embodiments, the precursor is heated at
temperatures greater than
600 C. In some embodiments, CO2 selectivity and CO2 capacity of the porous
carbon material
is enhanced by functionalization of the porous carbon material surface during
such heating. In
some embodiments, the precursor is activated at a temperature between about
650 C and about
1000 C in the presence of an amount of activating agent in order to create
and maintain
micropores within the porous carbon material.
[171] Advantages
[172] The gas capture methods and the porous carbon materials of the present
disclosure provide
numerous advantages over prior gas sorbents. For instance, the porous carbon
materials of the
present disclosure provide significantly higher CO2 and H2S sorption
capacities than prior
sorbents. Moreover, due to the availability and affordability of the starting
materials, the porous
carbon materials of the present disclosure can be made in a facile and
economical manner in bulk
quantities. Furthermore, unlike traditional gas sorbents, the porous carbon
materials of the
present disclosure can selectively capture and release CO2 and I-12S at
ambient temperature
without requiring a temperature swing. As such, the porous carbon materials of
the present
disclosure can avoid substantial thermal degradation and be used effectively
over successive
cycles without losing their original CO2 and H2S sorption capacities.
11731 Accordingly, the gas capture methods and the porous carbon materials of
the present
disclosure can find numerous applications. For instance, in some embodiments,
the gas capture
methods and the porous carbon materials of the present disclosure can be
utilized for the capture
of CO2 and H2S from subsurface oil and gas fields. In more specific
embodiments, the process
may take advantage of differential pressures commonly found in natural gas
collection and
processing streams as a driving force during CO2 and H2S capture. For
instance, in some
embodiments, the methods of the present disclosure may utilize a natural gas-
well pressure (e.g.,
33
CA 02901455 2015-08-25
a natural gas well pressure of 200 to 300 bar) as a driving force during CO2
and H2S capture.
Thereafter, by lowering the pressure back to ambient conditions after CO2 and
H2S uptake, the
captured gas can be off-loaded or pumped back downhole into the structures
that had held it for
geological timeframes. Moreover, the gas capture methods and the porous carbon
materials of
the present disclosure can allow for the capture and reinjection of CO2 and
H2S at the natural gas
sites, thereby leading to greatly reduced CO2 and H2S emissions from natural
gas streams.
[174] In some embodiments, the methods of the present disclosure can be
utilized for the
selective release of captured CO2 and H2S. For instance, in some embodiments
where a porous
carbon material has captured both CO2 and H2S, the lowering of environmental
pressure can
result in the release of CO2 from the porous carbon material and the
retainment of the captured
H2S from the porous carbon material. Thereafter, the captured H2S may be
released from the
porous carbon material by heating the porous carbon material (e.g., at
temperatures between
about 50 C to about 100 C). In additional embodiments where a porous carbon
material has
captured both CO2 and H2S, the heating of the porous carbon material (e.g., at
temperatures
between about 50 C to about 100 C) can result in the release of the captured
I-12S and the
retainment of the captured CO2. Thereafter, the lowering of environmental
pressure can result in
the release of CO2 from the porous carbon.
[175] Reference will now be made to more specific embodiments of the present
disclosure and
experimental results that provide support for such embodiments. However,
Applicants note that
the disclosure below is for illustrative purposes only and is not intended to
limit the scope of the
claimed subject matter in any way.
[176] EXAMPLE 1. Capture of CO2 by Sulfur- and Nitrogen-Containing Porous
Carbons
[177] In this Example, nucleophilic porous carbons are synthesized from simple
and inexpensive
carbon-sulfur and carbon-nitrogen precursors. Infrared, Raman and 13C nuclear
magnetic
resonance signatures substantiate CO2 fixation by polymerization in the carbon
channels to form
poly(CO2) under much lower pressures than previously required. This growing
chemisorbed
sulfur- or nitrogen-atom-initiated poly(CO2) chain further displaces
physisorbed hydrocarbon,
providing a continuous CO2 selectivity. Once returned to ambient conditions,
the poly(CO2)
34
CA 02901455 2015-08-25
spontaneously depolymerizes, leading to a sorbent that can be easily
regenerated without the
thermal energy input that is required for traditional sorbents.
[1781 More specifically, Applicants show in this Example that the new carbon
materials can be
used to separate CO2 from various environments (e.g., natural gas), where 0.82
g of CO2 per g of
sorbent (82 wt %) can be captured at 30 bar. A mechanism is described where
CO2 is
polymerized in the channels of the porous carbon materials, as initiated by
the sulfur or nitrogen
atoms that are part of the carbon framework. Moreover, no temperature swing is
needed. The
reaction proceeds at ambient temperature. Without being bound by theory, it is
envisioned that
heat transfer between cylinders during the exothermic sorption and endothermic
desorption can
provide the requisite thermodynamic exchanges.
[1791 In some instances, the process can use the natural gas-well pressure of
200 to 300 bar as a
driving force during the polymerization. By lowering the pressure back to
ambient conditions
after CO2 uptake, the poly(CO2) is then depolymerized, where it can be off-
loaded or pumped
back downhole into the structures that had held it for geological timeframes.
[180] Example 1.1 Synthesis and Characterization of Porous Carbons
[181] Sulfur- and nitrogen-containing porous carbons (SPC and NPC,
respectively) were
prepared by treating bulk precursor polymers with potassium hydroxide (KOH) at
600 C, as
described previously (Carbon 44, 2816-2821 (2006); Carbon 50, 5543-5553
(2012)).
[182] As shown in FIG. 3A, the resulting products were solid porous carbon
materials with
homogeneously distributed sulfur or nitrogen atoms incorporated into the
carbon framework.
They exhibited pores and channel structures as well as high surface areas of
2500 and 1490 m2/g
(N2, Brunauer-Emmett-Teller) for the SPC and the NPC, respectively, with pore
volumes of 1.01
cm 3 g -I and 1.40 cm3 g , respectively. The scanning electron microscopy
(SEM) and
transmission electron microscopy (TEM) images are shown in FIGS. 3B-D, and the
X-ray
photoelectron spectroscopy (XPS) analyses are shown in FIG. 4.
1183] Example 1.2 CO, Uptake Measurements
CA 02901455 2015-08-25
[184] For CO2 uptake measurements, samples were analyzed using volumetric
analysis
instruments. The measurements were further confirmed with gravimetric
measurements.
[185] FIG. 5 shows the pressure-dependent CO2 excess uptake for the SPC
sorbent at different
temperatures peaking at 18.6 mmol CO2 g-1 of sorbent (82 wt %) when at 22 C.
and 30 bar. The
sorption results measured by volumetric and gravimetric analyses were
comparable, as were
those measurements on the two volumetric instruments.
1186] Applicants chose 30 bar as the upper pressure limit in experiments
because a 300 bar well-
head pressure at 10 mol % CO2 concentration would have a CO2 partial pressure
of 30 bar. FIGS.
5B-D show three consecutive CO2 sorption-desorption cycles on SPC over a
pressure range from
0 to 30 bar, which indicates that the SPC could be regenerated using a
pressure swing process
while retaining its original CO2 sorption capacity.
[187] In the case of microporous materials with negligible external surface
area, total uptake is
often used as an approximation for absolute uptake, and the two values here
are within 10% of
each other. For example, the absolute CO2 uptake of the SPC was 20.1 and 13.9
mmol/g under 30
bar at 22 and 50 C, respectively. See FIGS. 6-7 and Example 1.8.
[188] Similarly, although absolute adsorption isotherms can be used to
determine the heat of
sorption, excess adsorption isotherms are more often used to calculate the
heat of CO2 sorption
(QCO2) before the critical point of the gas. Thus, the excess CO2 sorption
isotherms measured at
two different temperatures, 23 C and 50 C (FIG. 5E), were input into the
Clausius-Clapeyron
equation. At lower surface coverage (< 1 bar), which could be expected to be
more indicative of
the sorbate-sorbent interaction, the SPC exhibits a heat of CO2 sorption of
57.8 kJ/mo1-1.
Likewise, the maximum QCO2 values for nucicophile-free porous materials, such
as activated
carbon, Zeolite 5A and zeolitie imidazolate framework (ZIF-8, a class of the
MOF) were
measured to be 28.4, and 31.2, 25.6 kJ/mol, respectively, at low surface
coverage (see Example
1.9). Based on this data, the SPC possesses the highest CO2 sorption enthalpy
among these
complementary sorbents measured at low surface coverage.
[189] In order to better assess the sorption mechanism during the CO2 uptake,
attenuated total
reflectance infrared spectroscopy (ATR-IR) was used to characterize the
properties of the
36
CA 02901455 2015-08-25
sorbents before and after the CO2 uptake. A sample vial with ¨100 mg of the
SPC was loaded
into a 0.8 L stainless steel autoclave equipped with a pressure gauge and
valves. Before the
autoclave was sealed, the chamber was flushed with CO2 (99.99%) to remove
residual air, and
the system was pressurized to 10 bar (line pressure limitation). The sorbent
was therefore
isobarically exposed to CO2 in the closed system at 23 C. After 15 min, the
system was vented
to nitrogen at ambient pressure and the sorbent vial was immediately removed
from the chamber
and the sorbent underwent ATR-IR and Raman analyses in air.
[190] FIGS. 8A-B show the ATR-IR spectra of the SPC before (black line) and
after exposure to
bar of CO2, followed by ambient conditions for the indicated times. The two
regions that
appear in the ATR-IR spectra (outlined by the dashed-line boxes) after the CO2
sorption are of
interest. The first IR peak, located at 2345 cm-1, is assigned to the anti-
symmetric CO2 stretch,
confirming that CO2 was physisorbed and evolving from the SPC sorbent. The
other IR band,
centered at 1730 cm -1, is attributed to the C=0 symmetric stretch from the
poly(CO2) on the
SPC. Interestingly, this carbonyl peak is only observed with the porous
heteroatom-doped
carbon, such as the SPC and NPC. Other porous sorbents without nucleophilic
species, such as
ZIF-8 and activated carbon, only showed the physisorbed or evolving CO2 peak (-
2345 cm-1)
(FIGS. 9-10). Once the CO2-filled SPC returned to ambient pressure, the key IR
peaks attenuated
over time and disappeared after 20 min. Based on this data, the ATR-IR study
confirmed the
poly(CO2) formation. Raman spectroscopy was further used to probe individual
chemical bond
vibrations, as shown in FIG. 8C. The carbonaceous graphitic G-band and defect-
derived
diamonoid D-band were at 1590 and 1350 cm* The peak at 798 cm-1 can be
attributed to the
symmetric stretch of the C--0--C bonds, which was not observed for the other
nucleophile-free
porous materials, suggesting that the poly(CO2), with the --(0--C(=0))n--
moiety, was formed.
[191] Without being bound by theory, it is envisioned that the
monothiocarbonate and carbamate
anions within the channels of the SPC and NPC, respectively, were the likely
initiation points for
the CO2 polymerization since no poly(CO2) was seen in activated carbon (FIG.
10). Furthermore,
13C NMR also confirms the presence of the poly(CO2) formation. The sorbent
gives a broad
signal characteristic of aromatic carbon (FIG. 8D, bottom).
37
CA 02901455 2015-08-25
[192] After exposure to CO2, a relatively sharp signal on top of the broad
sorbent signal appears
at 130.6 ppm, which can be assigned to the CO2 that is evolving from the
support. A sharp signal
also appears at 166.5 ppm (FIG. 8D, middle) that is characteristic of the
carbonyl resonance for
poly(CO2). Both of these signals are gone 19 h later (FIG. 8D, top). These
assignments are
further discussed in detail in Example 1.10.
[193] Compared to secondary amine-based CO2 sorbents where maximum capture
efficiency is
0.5 mol CO2 per mol N (2 RNH2+CO2 RNH2 +- 02CNHR), the SPC and NPC demonstrate
a
unique mechanism during the CO2 uptake process resulting in their remarkably
higher CO2
capacities versus S or N content (8.1 atomic % of S and 6.2 atomic % of N in
the SPC and NPC,
respectively, by XPS analysis).
[194] FIGS. 8E and 8F show illustrations of the aforementioned CO2 -fixation
by
polymerization. Dimeric CO2 uptake has been crystallographically observed in
metal complexes,
and polymeric CO2 has been detected previously but only at extremely high
pressures of ¨15,000
bar. The spectroscopic determination here confirms poly(CO2) formation at much
lower
pressures than formerly observed.
[195] A series of porous materials with and without the nucleophilie
heteroatoms were tested to
compare their CO2 capture performance up to 30 bar at 30 C (FIG. 10A). The
SPC had the
highest CO2 capacity. The NPC, activated carbon, zeolite 5A and ZIF-8 had
lower capacities.
Although NPC had lower CO2 capacity than SPC, its uptake performance could be
improved by
21 wt % after 1-12 reduction at 600 C, producing rcduced-NPC (R-NPC) with
secondary amine
groups (FIG. 3A).
[196] Even though the surface area of R-NPC (1450 m2 g) is only slightly
greater than that of the
activated carbon (1430 m2 g), the presence of the amine groups induces the
formation of the
poly(CO2) under pressure, promoting the CO2 sorption efficiency of the R-NPC.
The pore
volume of R-NPC is 1.43 em3 g.
[197] Purification of natural gas from wells relies upon a highly CO2 -
selective sorbent,
especially in a CH4-rich environment. Thus, CH4 uptake experiments were
carried out on three
different types of porous materials, SPC, activated carbon and ZIF-8. FIGS.
11B-D compare CO2
38
CA 02901455 2015-08-25
and CH4 sorption over a pressure range from 0 to 30 bar at 23 C. In contrast
to the CO2 sorption,
the CH4 isotherms for these three sorbents reached equilibrium while the
system pressure was
approaching 30 bar. The order of the CH4 uptake capacities was correlated to
the surface area of
the sorbents. Comparing these sorbents, the observed molecular ratio of sorbed
CO2 to CH4
(nCO2/nCH4) for the SPC (2.6) was greater than that for the activated carbon
(1.5) and ZIF-8
(1.9). In addition, the density of the SPC calculated using volumetric
analysis is nearly 6-fold
higher than in the ZIF-8 (2.21 vs. 0.35 g/cm3) and 3-fold higher than the
zeolite 5A (2.21 vs. 0.67
g/cm3). The high CO2 capacity and high density observed for SPC greatly
increase the volume
efficiency, which would reduce the volume of the sorption material for a given
CO2 uptake
production rate.
[198] In order to mimic a gas well environment and further characterize the
SPC's selectivity to
CO2, a premixed gas (85 mol % CH4, 10 mol % CO2, 3 mol % C2H6 and 2 mol %
C3H8) was
used with quadropole mass spectrometry (MS) detection. The MS inlet was
connected to the gas
uptake system so that it could monitor the gas effluent from the SPC
throughout the sorption-
desorption experiment. FIG. 12 shows the mass spectrum recorded during the
sorption process.
The peaks at 15 and 16 amu correspond to fragment and molecular ions from CH4,
while the
peaks at 28 and 44 amu are from CO2 in the premixed gas. Other minor peaks can
be assigned to
fragment ions from C2H6 and C3H8. Although the peak at 44 amu can also come
from C3H8 ions,
the contribution is negligible because of the lower C3H8 concentration in the
mixed gas, and it is
distinguishable by the fragmentation ratios in the MS [C3H8: m/z=29 (100), 44
(30); CO2:
m/z=44(100), 28(11)1. The observed intensity ratio of two peaks at 16 and 44
amu (116444=9.1)
indicates the abundance of CH4 vs. CO2 during the sorption and also reflects
the relative amount
of CH4 and CO2 in the premixed gas. Once the sorption reached equilibrium
under 30 bar, the
desorption process was induced by slowly venting into the MS system. The
116/144 ratio reduced
to ¨0.7. The SPC has been shown to have 2.6-fold higher CO2 than CH4 affinity
at 30 bar when
using pure CO2 and CH4 as feed gases (FIG. 11B).
[199] If the binding energy of CH4 and CO2 were assumed to be similar, and the
partial pressure
of CH4 vs. CO2 in the premixed gas is considered (PCH4/PCO2=8.5), then it is
envisioned that
the number of sorbed CH4 should be about 3.3 times more than that of the
sorbed CO2. It is also
envisioned that CO2-selective materials have selective sites and once the CO2
occupies those
39
CA 02901455 2015-08-25
sites, the selectivity significantly decreases and the materials behave as
physisorbents with lower
selectivities at larger pressures. On the contrary, here the SPC demonstrates
much higher CO2
selectivity than expected since the chemisorbed sulfur-initiated poly(CO2)
chain displaces
physisorbed gas.
[200] Under the mechanism described here for CO2 polymerization in the
channels of
inexpensive nucleophilic porous carbons, these new materials have continuous
selectivity toward
CO2, limited only by the available pore space and pressure.
[201] Example 1.3 Instrumentations
[202] An automated Sieverts instrument (Setaram PCTPro) was adopted to measure
gas (CO2,
CH4 or premixed gas) sorption properties of materials. Typically, a ¨70 mg of
sorbent was
packed into a ¨1.3 mL of stainless steel sample cell. The sample was
pretreated under vacuum
(-3 mm Hg) at 130 C. for 6 h and the sample volume was further determined by
helium before
the uptake experiment. At each step of the measurement, testing gas was
expanded from the
reference reservoir into the sample cell until the system pressure reached
equilibrium. A
quadropole mass spectrometer (Setaram RGA200) was connected to the Sieverts
instrument so
that it could monitor the gas effluent from the sorbent throughout the entire
sorption-desorption
experiment. With the assistance of a hybrid turbomolecular drag pump, the
background pressure
of the MS can be controlled lower than 5 X10 -8 Torr. All material densities
were determined
using volumetric analysis on this same instrument.
[203] XPS was performed using a PHI Quantera SXM Scanning X-ray Microprobe
with a base
pressure of 5 X10-9 Torr. Survey spectra were recorded in 0.5 eV step size and
a pass energy of
140 eV. Elemental spectra were recorded in 0.1 eV step size and a pass energy
of 26 eV. All
spectra were standardized using Cls peak (284.5 eV) as a reference.
[204] The ATR-IR experiment was conducted using a Fourier transform infrared
spectrometer
(Nicolet Nexus 670) equipped with an attenuated total reflectance system
(Nicolet, Smart Golden
Gate) and a MCT-A detector. Raman spectra were measured using a Renishaw in
Via Raman
Microscope with a 514 nm excitation argon laser.
CA 02901455 2015-08-25
[205] Scanning electron microscope (SEM) images were taken at 15 KeV using a
JEOL-650017
field emission microscope. High-resolution transmission electron microscope
(TEM) images
were obtained with a JEOL 2100F field emission gun TEM.
[206] An automated BET surface analyzer (Quantachrome Autosorb-3b) was used
for
measurements of sorbents' surface areas and pore volumes based on N2
adsorption-desorption.
Typically, a ¨100 mg of sample was loaded into a quartz tube and pretreated at
130 C under
vacuum (-5 mm Hg) in order to remove sorbates before the measurement.
[207] MAS NMR spectra were recorded on a Bruker Avance III 4.7 T spectrometer
with a
standard MAS probe for 4 mm outer diameter rotors.
1208] ,Lxample 1.4 Volumetric COz_Sorption Experiments (NIST)
[209] CO2 sorption measurements were carried out on computer-controlled custom-
built
volumetric sorption equipment previously described in detail (J. Phys. Chem. C
111, 16131-
16137 (2007)) with an estimated reproducibility within 0.5% and isotherm data
error bar of less
than 2% compared to other commercial instruments. An amount of ¨79 mg of
sample was used
for the experiments. Sample degassing, prior to the CO2 sorption experiment,
was done at 130 C
under vacuum for 12 h.
[210] Example 1.5 Gravimetric CO2 Sorption Experiments
[211] CO2 sorption measurements were performed on a high pressure thermal
gravimetric
equipment (Model: TGA-HP50) from TA Instruments. An amount of ¨15 mg of sample
was
used for the experiments. Sample degassing, prior to CO2 sorption experiment,
was done at 130
C under vacuum for 12 h.
[212] Example 1.6 Synthesis of S-Containing Porous Carbon (SPC)
[213] Poly[(2-hydroxymethyl)thiophene] (PTh) (Sigma-Aldrich) was prepared
using FeC13
Microporous Mesoporous Mater. 158, 318-323 (2012). In a typical synthesis, 2-
thiophenemethanol (1.5 g, 13.1 mmol) in CH3CN (10 mL) was slowly added under
vigorous
stirring to a slurry of FeC13 (14.5 g, 89.4 mmol) in CH3CN (50 mL). The
mixture was stirred at
room temperature for 24 h. The polymer (PTh) was separated by filtration over
a sintered glass
41
1
CA 02901455 2015-08-25
funnel, washed with distilled water (-1 L) and then with acetone (-200 mL).
The polymer was
dried at 100 C. for 12 h to afford (1.21 g, 96% yield) of the desired
compound.
[214] The PTh was activated by grinding PTh (500 mg) with KOH (1 g, 17.8 mmol)
with a
mortar and pestle and then heated under Ar at 600 C. in a tube furnace for 1
h. The Ar flow rate
was 500 sccm. After cooling, the activated sample was thoroughly washed 3 X
with 1.2 M HCI
(1 L) and then with distilled water until the filtrate was pH 7. The SPC
sample was dried in an
oven at 100 C. to afford 240 mg of the black solid SPC. The BET surface area
and pore volume
were 2500 m2/g and 1.01 cm3/g, respectively.
[215] Example 1.7 Synthesis of N-Containing Porous Carbon (NPC)
[216] Commercial polyacrylonitrile (PAN, 500 mg, average Mw 150,000, Sigma-
Aldrich)
powder and KOH (1500 mg, 26.8 mmol) were ground to a homogeneous mixture in a
mortar.
The mixture was subsequently carbonized by heating to 600 C. under Ar (500
seem) in a tube
furnace for 1 h. The carbonized material was washed 3 times with 1.2 M EIC1 (1
L) and then with
distilled water until the filtrate was pH 7. Finally, the carbon sample was
dried in an oven at 100
C. to afford 340 mg of the solid black NPC.
[217] To produce R-NPC, the activated material (270 mg) was further reduced by
10% H2
(H2:Ar=50:450 seem) at 600 C. for 1 h to provide 255 mg of the final
material. The BET
surface area and pore volume were 1450 m2 g and 1.43 cm3 g, respectively.
[218] Example 1.8 Conversion of Excess Uptake to Absolute Uptake
[219] Total uptake includes all gas molecules in the adsorbed state, which is
the sum of the
experimentally measured excess uptake and the bulk gas molecules within the
pore volume (FIG.
6). For microporous materials with negligible external surface area, the total
uptake is often used
as an approximation for absolute uptake and could be represented in the
following equation:
[220] Nowt Nabs = Nex.+Vp p bulk(P,T)
[221] [0134] In the above equation, Vp is the pore volume of porous material
and p bulk is the
density of gas in the bulk phase at given pressure and temperature. In the
case of SPC, the pore
volume was determined to be 1.01 cm3 g by N2 adsorption isotherm at 77 K (BET
analysis). The
42
CA 02901455 2015-08-25
CO2 density changes from 0.00180 to 0.06537 g/cm-3 in the pressure range
between 1 and 30 bar
at 22 C. and 0.00164 to 0.05603 g/cm3 at 50 C.
[222] Example 1.9 Determination of the Heat of CO2 Sorption (0)
[223] The Clausius-Clapeyron equation (Adsorption 175, 133-137 (1995)) was
used to determine
the heat of CO2 sorption.
(8 in/
) To RT2
[224]
[225] In the above equation, 0 is the fraction of the adsorbed sites at a
pressure P and
temperature T, and R is the universal constant. The equation can be further
derived as the
following expression for transitions between a gas and a condense phase:
Q(1 1
in P2 -in P1 ¨ ¨ ¨ ¨
RT1 T2
[226] Table I below compares the heat of CO2 sorption to values in the
literature.
43
CA 02901455 2015-08-25
TABLE 1
Heat of CO2 sorption determined in
Example 1 versus literature values.
Comparison with
Q CO2 (kJ rr101-1) reference
SPC 57.8 59.01
Activated carbon 28.4 28.92
Zeolite 5A 31.2 33.73
ZIF-8 25.6 27.04
Ref. 'Carbon 50, 5543-5553 (2012).
Ref. 2.7. Natural Gas Chem. 15, 223-229 (2006).
Ref. 3Handbook ofZeolite Science and Technology, Marcel Dekker, Inc. NewYork
(2003).
Ref. 4,41ChE J. 59, 2195-2206 (2013),
[227] Example 1.10 Evaluation of the 13C NMR Assignments
[228] The three NMR spectra in FIG. 8D were obtained under identical
conditions: 12 kHz
MAS, 2.5-[is 900 13C pulse, 41-ms FID, 10-s relaxation delay; 480 scans; and
50 Hz of line
broadening applied to the FID.
[229] Numerous MAS NMR investigations of CO2 have reported a signal at 125 1
ppm,
regardless of the physical environment for the CO2 (e.g., free gas,
physisorbed on various
materials, in a metal organic framework, in a clathrate, dissolved in a glass,
etc.) Accordingly,
attributing the signal at 130.6 ppm to CO2 physisorbed on the sorbent seems
reasonable, although
the reason for the additional deshielding may not be apparent. It is
envisioned that this 5-ppm
difference does not result from the use of different chemical shift
references, as the various
reports indicate that either the signal from Si(C113)4 (TMS) serves as the
chemical shift reference
(0 ppm) or that the signal from a solid such as adamantane or glycine (this
work) relative to TMS
at 0 ppm serves as the chemical shift reference. Applicants note that the
sorbent is somewhat
conductive in that it has a noticeable effect on the tuning and matching of
the 13C and 1H
channels of the NMR probe (relative to the tuning and matching for glycine).
However, spinning
is unaffected. Without being bound by theory, it is envisioned that the
conductive nature of the
sorbent results in the 5-ppm deshielding effect observed for physisorbed CO2.
44
CA 02901455 2015-08-25
[230] A chemical shift of 166.5 ppm is rational for poly(CO2) in light of
various reports of
bicarbonate and carbonate species giving signals from 162 to 170 ppm relative
to TMS or to
[(CH3)3Si]4Si, which is 3.5 ppm relative to TMS at 0 ppm. The carbonyl
chemical shift of
CH3O¨00-0¨CO¨OCH3 is extremely sensitive to its environment (the reported
shift is 147.9
ppm as a neat liquid at 37 C. and 157 ppm in CDC13, both relative to TMS).
Applicants are not
aware of any reports of chemical shift data for poly(CO2) and are hereby
reporting the first such
example of that chemical shift at 166.5 ppm when entrapped in this carbon
matrix.
12311 EXAMPLE 2. CQ/Absorption Capacities of Different Carbon Materials
[232] In this example, the CO2 uptake capacities of SPC, R-NPC, rice protein,
ZIF-8 and Zeolite
5A were compared. The CO2 uptake measurements were conducted at 30 C. and 30
bar.
[233] As shown in FIG. 13, the CO2 uptake capacities of SPC and R-NPC were
significantly
higher than the CO2 uptake capacities of ZIF-8, rice protein, and Zeolite 5A.
[234] EXAMPLE 3. Asphalt-Derived Porous Carbons for CO2 Capture
[235] In this Example, Applicants report the preparation and CO2 uptake
capacity of
microporous carbon materials synthesized from asphalt. Carbonization of
asphalt with potassium
hydroxide (KOH) at high temperatures (>873 K) yields asphalt-derived porous
carbons (A-PC)
with Brunauer¨Emmett¨Teller (BET) surface areas of up to 2800 mg and CO2
uptake capacities
of up to 25 mmol/g at 30 bar and 298 K. Further nitrogen doping of the A-PCs
yields active N-
doped A-PCs (also referred to as A-NPCs) containing up to 9.3 wt% nitrogen.
The A-NPCs have
enhanced BET surface areas of up to 2900 m2g-1 and CO2 uptake capacities of up
to 1.2 g at 30
bar and 298 K. Asphalt derived porous carbon with pre-treatment at 400 C had
measured BET
surface areas of 4200 m2 /g and CO2 uptake capacities of up to 1.3 g at 30 bar
and 298 K. To the
best of Applicants' knowledge, such results represent the highest reported CO2
uptake capacities
among the family of activated porous carbon materials. Thus, the porous carbon
materials
derived from asphalt demonstrate the required properties for capturing CO2 at
a well-head during
the extraction of natural gas under high pressure.
12361 I )(ample 3.1. .5yitthesis and charaetcrirdtion =of avlialt-derived
porous carbon ina-wrials
CA 02901455 2015-08-25
[237] Asphalt-derived porous carbons (A-PCs) were prepared by carbonization of
a molded
mixture of asphalt and potassium hydroxide (KOH) at higher temperatures under
inert
atmosphere (Ar). The treatment of asphalt with KOH was conducted at various
temperatures
(200 - 800 C) and asphalt/KOH weight ratios (varied from 1/1 to 1/5). In
addition, the reaction
conditions were adjusted and tuned by the CO2 uptake performance of the final
porous carbon
materials.
[238] In a more specific example, A-PC was synthesized at 700 C at an
asphalt:KOH weight
ratio of 1:4. As shown in FIG. 14, the produced A-PC has a steep nitrogen
uptake at low
pressures (0-0.3 P/Po), indicative of the large amount of microporous
structures with uniform
distribution of pore sizes ¨ 1.3 nm (sec FIG. 15 inset). The BET surface area
(2779 m2/g) and
the pore volume (1.17 cm3/g) were calculated from the nitrogen isotherms (see
Table 2). X-ray
photoelectron spectroscopy (XPS) of the A-PC showed C Is and 0 Is signals with
¨10 wt% of
oxygen content, which are assigned to C-0 and C=0 functional groups (data not
shown).
[239] Scanning electron microscopy (SEM) images of the A-PCs show porous
materials with
uniform distribution of the micropores (FIG. 14A). Uniform distribution of the
micropores are
further indicated by the transmission electron microscopy (TEM) images (FIG.
14B) that show
pore diameters of about 1.5 nm, which is very close to the number extracted
from nitrogen
absorption isotherms.
[240] Treatment of A-PCs with NH3 at elevated temperatures resulted in N-doped
porous carbon
materials (A-NPC) (FIG. 16A). The nitrogen content and the surface area
increased considerably
after treatment of A-PCs with NH3 at higher temperatures, as shown in Tables 2
and 3. This
leads to the formation of A-NPCs with a nitrogen concentration of up to 9.3
wt%.
46
CA 02901455 2015-08-25
Pmpenies and CO, uptake capacities of various porous carbons.
Pore CO, uptake
SBET volume Density capacity at 30 bar
Samples (m)/g (cm3/g)' (g/cm3) (gig)5
A-PC 2779 1.17 2 0.96
A-NPC 2858 1.20 2 1,10
A-rNPC 2583 1.09 2 1.19
SPC 2500 1.01 2.21 0.74
NPC 1490 1.40 1.8 0.60
rNPC 1450 1.43 1.8 0,67
'Estimated from N2 absorption isotherms at 77K, where samples were h red at
200 C. for
20 h prior to the measurements.
5CO2 uptake capacity at 23 C.
Table 2. Properties and CO2 uptake capacities of various porous carbons.
Elemental composition and CO2 uptake capacities
of activated 'morn carho'is
CO2
XPS uptake
Pyri- Pyr- Gra- capacity
dinic rolic phitic at 30 bar
Samples C% 0% N% N% N% N% (g/g)"
A-NPC(500) 91.1 6.1 2.7 29.7 63.3 7.0 1.02
A-NPC(600) 90.6 6.4 3.0 33.1 52.6 14.3 1.04
A-NPC(700) 91.1 4.2 4.7 53.2 41.4 5.4 1.06
A-NPC(800) 81.0 9.7 9.3 52.3 45.4 2.3 0.93
A-rNPC 88.0 7.5 4.5 55.1 40.3 4.6 1.19
'CO2 uptake capacity at 23 C.
Table 3. Elemental composition and CO2 uptake capacities or activated porous
carbons.
[241] The surface N-bonding configurations reveal three main nitrogen
functional groups in the
surface of the carbon framework. As shown in FIG. 14A, the N Is spectra at
variable doping
temperatures deconvoluted into three peaks with binding energies of about 399,
400.7 + 4, and
about 401.7. These binding energies arc in the range of typical binding
energies corresponding to .
pyridinie N, pyrollic N and graphitic N, respectively. The new peak at the
binding energy of
about 396 was observed at 800 C, which was assigned to the N-Si binding
energy. Without
being bound by theory, it is envisioned that, at high pyrolysis temperatures,
NI-13-doping of silica
from the quartz reaction tube starts to interfere with the doping process.
47
CA 02901455 2015-08-25
[242] Further H2 treatment of A-NPCs at 700 C resulted in formation of reduced
A-NPCs (A-
rNPC). The elemental composition and the surface area of the A-rNPCs were
investigated using
XPS (see FIG. 14B and Table 3). The XPS spectrum of the produced A-rNPCs (FIG.
14B) is
similar to the XPS spectrum of A-NPCs (FIG. 14A). A schematic representation
of the synthetic
route for the production of A-rNPCs is shown in FIG. 16A.
[243] Applicants also observed that, as reaction temperatures increased, the
relative trend of the
pyrrolic nitrogens in A-NPCs increased. However, the opposite was observed for
pyridinic
nitrogens. These results indicate that pyrolysis temperature during NH3
treatment plays a
significant factor in determining the CO2 uptake performance of A-NPCs.
[244] Example 3.2. CO) uptake capsteitv of the asphalt derived porous carbon
materials
[245] The CO2 uptake capacities of A-PC, A-NPC, and A-rNPC were compared to
the CO2
uptake capacities of prior porous carbon materials, including nitrogen
containing nucleophilic
porous carbons derived from poly(acrylonitrile) (NPCs), sulfur containing
porous carbons
derived from poly[(2-hydroxymethyl)thiophene (SPCs), commercial activated
carbon, and
asphalt (the NPCs and SPCs were described previously in PCT/US2014/044315 and
Nat
Commun., 2014 Jun 3, 5:3961, doi: 10.1038/ncomms4961). The CO2 uptake
capacities were
measured by a volumetric method at room temperature over the pressure range of
0-30 bar. The
results are shown in FIG. 17.
[246] Applicants also observed that volumetric CO2 uptake by A-PC, A-NPC and A-
rNPC do
not show any hysteresis (data not shown). Such observations suggest that the
asphalt-derived
porous carbon materials uptake CO2 in a reversible manner. The CO2 uptake
capacities at a
pressure of 30 bar arc summarized in Tables 2 and 3.
[247] A-rNPC has the highest CO2 uptake performance at 30 bar, although the
highest surface is
obtained for A-NPC. As Applicants increased the N-doping temperature (from 500
to 800 C),
pyrollic nitrogen starts to decrease in intensity, which is linearly
proportional to the CO2 uptake
performance of the A-NPCs (see Table 3). Thus, without being bound by theory,
Applicants
envision that pyrrolic nitrogens play a more significant role in CO2 uptake
performance than the
bulk nitrogen content of the porous carbon material.
48
CA 02901455 2015-08-25
[248] FIG. 18 shows the high and low pressure CO2 uptake capacity of A-rNPC as
temperature
increases. As in other solid physisorbcnts such as activated carbons, zeolites
and MOFs, the CO2
uptake capacity decreases with increasing temperature. However, when compared
with
commercial activated carbon and SPC, the decrease in CO2 uptake at higher
temperature is
lower. This suggests the higher and uniform microporosity of A-rNPCs, or the
efficacy of
poly(CO2) formation.
[249] Another key property of the activated carbon materials is the CO2/CH4
selectivity. In order
to evaluate the CO2/CH4 selectivity of A-PC, A-NPC and A-rNPCs, Applicants
compared CH4
uptake performances with SPC, activated carbon, and ZIF-8 sorbents over the 0-
30 bar pressure
range at 23 C. FIG. 19 shows the comparison of the CO2 and CH4 sorption
capacities of A-rNPC
and SPC. A-rNPCs have higher CH4 (8.6 mmol/g) uptake relative to SPC (7.7
mmol/g) at 30 bar,
which is in agreement with the higher surface area for A-rNPC (2583 m2/g) than
the SPC (2500
m2/g).
[250] The molar ratios of sorbed CO2 and CH4 (nCO2/nCH4) were estimated as the
ratios of the
amount of absorbed gases at 30 bar. The measured nCO2/nCH4 for A-rNPC was
found to be
about 3.5. This value was compared to values for SPC (2.6), activated carbon
(1.5) and ZIF-8
(1.9).
[251] In addition, the isosteric heat of absorption of CO2 and CH4 on the
surfaces of A-PC, A-
NPC and A-rNPC were calculated using low pressure CO2 sorption isotherms at 23
C and 80 C.
The measured value was found to be about 27 kJ/mol.
[252] ,Examek 3.3 C0,7, uptake capacity of asphalt dell ved_wrous carbon with
pre-it eatment
[253] Similar to example 3.1, asphalt-derived porous carbons were prepared by
carbonization of
a molded mixture of asphalt and potassium hydroxide (KOH) at higher
temperatures under inert
atmosphere (Ar). The treatment of asphalt with KOH was conducted at various
temperatures
(200 - 800 C) and asphalt/KOH weight ratios (varied from 1/1 to 1/5). An
additional pre-
treatment step of heating the asphalt prior to mixing with KOH for
carbonization was done to
remove volatile oils found within the asphalt source (FIG. 31). In this
specific example,
untreated Gilsonite (uGil) was heated specifically at 400 C, then mixed with
KOH, and
49
CA 02901455 2015-08-25
subsequently reacted at temperatures 600 C and greater to tune the CO2 uptake
performance of
the final porous carbon materials. Table 4 summarized the high surface area
and even higher
CO2 uptake capacity achievable with pre-treatment and increasing reaction
temperature.
[254] Figure 20 shows the gravimetric CO2 uptake and CH4 uptake of various
porous carbon
samples made from Gilsonite and measured under high pressure. The molar ratios
of sorbed CO2
and CH4 (nCO2/nCH4) were estimated as the ratios of the amount of absorbed
gases at 30 bar.
The measured nCO2/nCH4 for uGi1-800 and uGi1-900 were found to be
approximately 8 (results
not shown). This value can be compared to values for A-rNPC (3.5), SPC (2.6),
activated carbon
(1.5) and ZIF-8 (1.9). Such CO2 uptake capacities (i.e., up to 30 mmol/g) are
the highest reported
CO2 uptake capacities among the activated carbons. Such CO2 uptake capacities
are also
comparable to the highest CO2 uptake capacities of synthetic metal-organic
frameworks (M0Fs).
Total pore CO2 uptake capacity
SBET DpOre XPS
Samples volume at 30 bar
(na2/g)a (nm)c
(crn3/g)b C % 0 % mmol/g wt%
uGi1-600 2300 1.31 2.13 84.9 15.1 18.6 82
uGi1-700 3800 2.11 2.21 88.7 11.3 23.8 105
uG11-800 3900 2.22 2.25 91.5 8.5 25.7 113
uGi1-900 4200 2.41 2.30 92.1 7.9 29.1 128
a Surface area estimated from N2 absorption isotherms at 77 K; samples dried
at 240 C for 20 h
prior to the measurements. b Total (micro- and meso-) pore volume obtained at
P/Po ¨ 0.994.
, = d CO2 ...
Average pore diameter (Dpore1uptake at 23 C.
Table 4. Properties and CO2 uptake performances of activated porous carbons
made from
Untreated Gilsonite.
[255] EXAMPLE 4. Asphalt-Derived Porous Carbons for CO2 and H2S Capture
[2561 This Example pertains to the further production and characterization of
A-NPCs, A-SPCs,
A-rNPCs, and A-NSPCs. In addition, this Example pertains to the use of the
aforementioned
carbon materials for the capture of both CO2 and 1I2S.
CA 02901455 2015-08-25
12571 l'Aam_ple 4.1. Synthesis and characterization of asphal t-derived porous
carbon materials
[258] Asphalt carbon sources were ground with KOH in a mortar. The weight
ratio of KOH to
the asphalt carbon source was from about 1:3 to about 1:4. The homogeneous
powder was heated
at 500-800 C under Ar atmosphere for 1 hour. This was followed by filtration
and washing with
wt% HC1(") and copious amounts of DI water until the extracts were neutral.
The filtered
sample was then dried at 110 C until a constant weight was obtained. The
above steps produced
A-PC.
[259] A-NPC was prepared by annealing the A-PC at 700 C for 1 hour under an
NH3-containing
atmosphere. A-rNPC was prepared by further reduction of A-NPC with 10 wt% H2
at 700 C for
1 h. A-SPC was prepared by exposing the A-PC to a sulfur source and annealing
the sulfur
impregnated A-PC at 650 C for 1 h. A-NSPC was prepared by annealing the
produced A-SPC
for 1 hour under an NH3-containing atmosphere to yield A-NSPC.
[260] Next, the produced porous carbon materials were characterized and tested
for uptake of
CO2 and H2S. The results are summarized in Table 5.
co,
Textural 112S Uptake
Properties Chemical Composition Uptake Capacity
________________________________ (atomic %) Capacity at 30 bar
Sample (m2/g) N C 0 S (gig) (gig)
Asphalt* 0.6 0.05
A-PC 2,613 0.5 91.4 8.1 - 1.06 0.92
A-NPC 2,300 5.7 91.0 3.3 - 1.50 1.01
A-rNPC 2,200 3.6 92.7 3.7 -- 2.05 1.12
A-SPC 2,497 90.3 7.1 2.7 1.16
A-NSPC 2.510 1.6 86.7 11.0 0.7 1.32
Table 5. The properties and gas uptake capacities of various asphalt-derived
porous carbon
materials. Asphalt-Versatrol HT Gilstonite, a naturally occurring asphalt from
MI SWACO, was
used as a control. The 112S uptake capacities of the porous carbon materials
were measured as a
function of the amount of sulfur retained on the porous carbon material.
12611 In order to characterize the H2S uptake capacities of the porous carbon
materials, the
porous carbon materials were first dried at 120 C for 1 hour under vacuum
(0.05 Ton). Next,
the porous carbon material was treated with H2S under an air flow for 1 hour.
The amount of
51
CA 02901455 2015-08-25
sulfur retained on the porous carbon material was measured by
thermogravimetric analysis
(TGA).
[262] After H2S uptake and air oxidation to S, A-rNPC was further
characterized by TEM EDS
elemental mapping. As shown in FIG. 21, sulfur is uniformly distributed within
the pores of A-
rNPCs. In addition, the TGA curve of the A-rNPCs after H2S uptake and
conversion to sulfur is
shown in FIG. 21.
[263] The H2S uptake of A-rNPC was also measured under different conditions,
including inert
or oxidative conditions. The results are summarized in FIG. 23. The results
show that A-rNPC
can capture H2S effectively in the presence of 02 from air. When CO2 was
present, A-rNPC also
showed H2S capture behavior. The air conditions can mimic H2S capture by
porous carbon
materials during natural gas flow from a wellhead, injection of a slug of air
to convert the sorbed
H2S to S, and the continuation of H2S capture from the natural gas source.
[264] Without being bound by theory, it is envisioned that, as a result of the
basic functional
groups on the surface of A-NPCs and A-rNPCs, and as a result of the pH values
of A-NPCs
(pH=7.2) and A-rNPCs (pH=7.5), the porous carbon materials of the present
disclosure can
capture H2S by an acid-base reaction, where an amine group on the porous
carbon abstracts a
proton from H2S to yield the ammonium salts and hydrogen monosulfide anions
according to the
following scheme:
R3N (where R is the carbon scaffold or a proton) + H2S R3NH+ or R2SH+ + HS
[265] In this case, the equilibrium constant (keg) is ¨1000 based on the pKa
values of the starting
materials (H2S) and products (ammonium species). As a result of the reaction
of HS ions with 02
from air introduced in the carbon support, the captured H2S produces sulfur
products such as S,
SO2 and H2SO4. The catalytic oxidation of H2S on A-NPC, A-rNPC and A-PC can
proceed at
room temperature by air oxidation.
[2661 Applicants also observed that nitrogen doping doubles the H2S capturing
capacity of the
porous carbon materials (FIGS. 22-23 and Table 5). Without being bound by
theory, it is
envisioned that the extent of oxidation appears to be driven by the
distribution of the catalytic
centers, such as nitrogen-containing basic functional groups. Additionally,
Applicants observed
52
CA 02901455 2015-08-25
that the oxidative capturing of H2S by A-PCs can form sulfur-impregnated A-PCs
(A-SPCs)
upon heating at 650 C (FIG. 1613).
[267] The CO2 uptake capacities of the porous carbon materials were also
evaluated. As shown
in FIG. 24, the CO2 uptake capacities of A-NPCs and A-rNPCs were evaluated
from 0 bar to 30
bar at 23 C. A-rNPC exhibits high CO2 uptake capacity (1.12 g CO2/g ArNPC)
under a higher
pressure environment, which is 5 times higher than Zeolite 5A, and 3 times
higher than ZIF-8
under the same conditions. Such CO2 uptake capacities also exceed about 72 wt%
of the CO2
uptake capacities observed on nitrogen-containing porous carbon (NPC) that
were reported in
Applicants' pervious patent application (PCT/US2014/044315).
[268] As shown in FIG. 25, the CO2 uptake capacities of A-SPCs and A-NSPC were
also
evaluated from 0 to 30 bar at 23 C. The A-NSPCs had been made according to
the scheme
illustrated in FIG. 16B, where it already completed its life as an H2S capture
material, with air
oxidation to a sulfur-rich carbon, then thermalization to form A-SPC, or
further exposure to NH3
to form the A-NSPC. These latter two materials are shown in FIG. 25 to be used
for reversible
capture of CO2. This underscores the utility life of these porous carbon
materials-- first for
irreversible capture of H2S as sulfur in over 200 wt% uptake, and then
conversion to A-SPC or
A-NSPC for reversible capture of CO2 in over 100 wt% uptake. A-SPCs exhibited
high CO2
uptake capacities (in excess of 1.10 g CO2/g A-SPCs) under pressure
environment, which is 5
times higher in uptake of CO2 than Zeolite 5A, and 3 times higher in uptake of
CO2 than ZIF-8
under the same conditions. Such CO2 uptake capacities also exceed about 89 wt%
of the CO2
uptake capacities observed on sulfur-containing porous carbons (SPC) reported
in Applicants'
pervious patent application (PCT/US2014/044315).
[269] EXAMPLE 5. Synthesis of Porous Carbon Materials
[270] In this Example, Applicants provide exemplary schemes for the synthesis
of porous carbon
materials.
[271] Example 5.1. Scheme A
[272] Carbon sources suitable for use in the present disclosure are mixed with
a vulcanization
agent and heated to 180 C for 12 hours in accordance with the following
scheme:
53
CA 02901455 2015-08-25
=
Carbon source + vulcanization agent porous carbon material
[273] The weight ratio of the vulcanization agent to the carbon source varied
from 5 wt% to 200
wt% relative to the carbon source. The vulcanized carbon source obtained was
then treated with
KOH, as described in Example 2.1.
[274] Example 5.2. Scheme B
[275] Carbon sources suitable for use in the present disclosure are mixed with
a vulcanization
agent and elemental sulfur and heated to about 180 C for 12 h in accordance
with the following
scheme:
Carbon source + vulcanization agent + elemental sulfur porous carbon material
1276] The weight ratio of the vulcanization agent to the carbon source varied
from 5 wt% to 200
wt% relative to the carbon source. The obtained vulcanized carbon source was
then treated with
KOH as described in Example 2.1.
[277] Example 5.3. Scheme C
[278] Carbon sources suitable for use in the present disclosure are mixed with
a vulcanization
agent, elemental sulfur, and KOH in accordance with the following scheme:
Carbon source + vulcanization agent + KOH --> porous carbon material
[279] The homogeneous powder is then heated at 600-800 C under Ar atmosphere
for 1 hour.
This is followed by filtration with 10 wt% HC1(aq) and copious amounts of DI
water. The weight
ratio of the vulcanization agent was chosen from 5 wt% to 200 wt% additive
relative to the
carbon source. The weight ratio of KOH to the carbon source varied from 1 to
3.
12801 Example 5.4. Scheme D
[281] Carbon sources suitable for use in the present disclosure are mixed with
a vulcanization
agent, elemental sulfur, and KOH in accordance with the following scheme:
Carbon source + vulcanization agent + elemental sulfur + KOH --> porous carbon
material
54
CA 02901455 2015-08-25
[282] The homogeneous powder is then heated at 600-800 C under Ar atmosphere
for 1 h. This
is followed by filtration with 10 wt% HC1(õ) and copious amounts of DI water.
The weight ratio
of the elemental sulfur to the carbon source varied from 0.2 to 1. The weight
ratio of the
vulcanization agent to the carbon source varied from 5 wt% to 200 wt% relative
to the carbon
source. The weight ratio of KOH to the carbon source was chosen from 1 to 3.
[2831 In summary, Applicants have demonstrated in Examples 1-3 the first
successful synthesis
of microporous active carbons with uniform distribution of pores sizes from
asphalt. Applicants
subsequently activated the asphalt derived porous carbon materials with
nitrogen functional
groups. By changing the reaction conditions, the porous carbon materials can
possess variable
surface areas and nitrogen contents. The CO2 and H2S uptake capacities of the
asphalt-derived
porous carbon materials are higher than other porous carbon materials.
Additionally, many of the
porous carbon materials derived from asphalt exhibit greater CO2:CH4
selectivity than other
porous carbon materials. Furthermore, as summarized in Table 6, the carbon
sources of the
present disclosure are much more affordable than the carbon sources utilized
to make other
porous carbon materials.
Carbon Source Cost
2-thiophene methanol (to make traditional SPC) $150 / 100 g (Aldrich)
Polyacrylonitrile (to make traditional NPC) $180 / 100 g (Aldrich)
Whey Protein $11 / lb
Rice Protein $9 / lb
Coal $70-150 / ton
Asphalt $70-750 / ton
[2841 Table 6. A comparison of the costs of various carbon sources.
[285] Example 5.5 Scheme E
12861 Carbon sources suitable for use in the present disclosure are initially
heated at 400 C.
This allows for the removal of volatile oils that are present in the carbon
source (FIG 31). This
is termed the pre-treatment step in the synthesis of porous carbon. The pre-
treated carbon
source is thoroughly mixed with KOH in accordance with the following scheme:
CA 02901455 2015-08-25
pretreatment at 400 C KOH, T (C)
Asphalt - Asphalt-a _____________ Asphalt-T
[287] The homogeneous powder is then heated at 600-900 C under Ar atmosphere
for 1 hour.
This is followed by filtration with 10 wt% HC100 and copious amounts of DI
water. The weight
ratio of 1(011 to the carbon source was chosen from 1 to 4.
[288] EXAMPLE 6. Synthesis of Porous Carbon Materials from Biomass
[289] In some embodiments, additional low cost raw materials may be used to
prepare the
porous carbon materials of the invention. For example, the porous carbon
materials of the
present disclosure may be derived from at least one of biochars hydrochars,
charcoals, wood
waste, activated carbon, and combinations thereof The embodiments (e.g., B-PC
and B-NPC
materials) may be produced in a one-step synthesis method which is simple,
inexpensive and
easy to scale up. In some embodiments, the porous carbon materials of the
present disclosure can
be easily prepared from low-cost or negative-cost biomass by pyrolysis in the
presence of little
or no oxygen at temperatures of 200-900 C. In some embodiments, the biomass
includes
agricultural crops, crops residues, plantations, grass, wood, animal litter,
dairy manure, solid
waste, and combinations thereof. In some embodiments, the biomass utilized to
make the porous
carbon materials of the present disclosure is abundant (in fact, people have
to pay money to get
rid of biomass waste).
[290] In some embodiments, hydrochar, charcoal and other carbon-containing
materials can be
utilized for the manufacture of the porous carbon materials of the present
disclosure. I Iydrochar
is similar to biochar and it is produced by hydrothermal carbonization of
biomass under pressure
in the presence of water at high temperature (typically 150-300 "C). Charcoal
is also similar to
biochar, although it is often used for fuel and energy generation.
[291] Therefore, the porous carbon materials of the present disclosure can be
prepared by simple
and economical synthesis procedures from abundant and inexpensive precursors
to make solids
for the capture of CO2 and I I2S. Moreover, the porous carbon materials of the
present disclosure
are environmentally attractive. For example, trees and plants, when alive,
capture CO2 and
convert it to oxygen and carbon. Here, Applicants show that trees and plants,
when dead, can
56
CA 02901455 2015-08-25
continue to trap CO2. And since the porous carbon materials of the present
disclosure (e.g., B-PC
and B-NPC) are reusable many times, the CO2 capture efficacy of a "dead" tree
or plant can
exceed that of the living tree or plant. Moreover, the porous carbon materials
of the present
disclosure (e.g., B-PC and B-NPC) can be manufactured on industrial scales.
12921 In some embodiments, the porous carbons of the present disclosure can be
made by the
following steps:
a. Biochar KOH Porous carbon
(carbon sources*) 00 C, Ar (B-PC)
N-contain in
Biochar
b. + Melamine KOH P. Porous carbon
(carbon sources*) Resin 800 C. Ar
12931 Carbon sources can include, without limitation, biochar (e.g., biochar
from mesquite,
applewood, corncobs and corn stover, straw from wheat, bagasse, lignin, urban
tree cutting, bull,
dairy, hazelnut, oak, pine, food, paper, cool terra, waste, etc); charcoal
(e.g., charcoal from wood,
saw dust, other wood waste, etc); activated carbon from various sources, and
combinations
thereof. Melamine resin can also be replaced by melamine. Sulfur-containing
organics, such as
those used in crosslinIcing rubber, can be used to make the sulfur analogs, B-
SPC, which can
likewise capture CO2 and H2S.
[2941 Synthesis of porous carbon materials, B-PC and I3-NPC. (a) Synthesis of
biochar derived
porous carbon (B-PC). The carbon sources listed above were mixed with KOI I in
a mortar. The
weight ratio of KOH to carbon sources was chosen from 2 to 6 and the
carbonization temperature
was chosen in the range of 600 C to 900 C. The product was filtered and
washed with DI water
until the effluent was neutral, followed by drying at 110 C in the oven for
12 h. (b) Synthesis of
biochar derived nitrogen-containing porous carbon (B-NPC). The carbon sources
and melamine
resin were mixed with KOH in a mortar. The ratio of KOH to carbon sources was
chosen from 2
to 6, the ratio of melamine to carbon source was chosen from 0 to 1, and the
carbonization
temperature was chosen from 600 C to 900 C. The product was purified and
dried in the same
way as B-PC.
57
CA 02901455 2015-08-25
[295] Figure 26. (a) SEM image of B-NPC and, (b) TEM image of B-NPC, (c) BET
isotherm
curve of B-NPC, indicating B-NPC is microporous material with surface area of
2988 m2/g, (d)
DFT size distribution of B-NPC and the pore size is from 0.5-5 urn.
. -
'
1
'Sarni)
.. ,
'
(timbal- 9.9 1.6 83.5 14.9 - 0.14
B-PC 2,988 - , 93.0 7.0 -
1.13
B-NPC 2.908 0.6 91.4 9.0 0.41 1.14
[2961 Table 7. l'hysical and chemical properties and CO2 uptake and 1-12S
uptake of biochar
derived porous carbon. The weight ratio of K011 to biochar is 5 and the
carbonization
temperature is 800 C. (Biochar was Mesquite biochar pyrolyzed at 450 C.
' . = t ' c,,itital ,,
'
,..,..c.s._'µ
B-PC(l) 0.50 0 2.50 2988 40 1.13
B-P(.' (2) 0.50 0 3.00 2755 28 (.15
B-NPC (1) 0.50 0.25 2.50 2908 45 1.14
13-NP(.: (2) 0.50 (1.25 3.00 3133 41 1.20
B-NPC (3) 0.50 0.25 3.50 2273 20 1.05
C-NPC 0.50* 0.75 2.50 3469 28
1.26
*Activated charcoal from Sigma Aldrich (CAS C3345, Lot # 051M0151M xxxx) is
used as
precursor.
[2971 Table 8. Physical properties and CO2 uptake of different biochar derived
porous carbons.
(Biochar was Mesquite biochar pyrolyzed at 450 C.
58
1
CA 02901455 2015-08-25
[298] Figure 27. CO2 uptake performances of different sorbents, B-NPC and C-
NPC (charcoal
derived N-containing porous carbon) at 25 C. B-NPC derived from mesquite
exhibits high CO2
capacity (1.14 g/g) at 30 bar, which is 5 times higher than Zeolite 5A, 3
times higher than ZIF-8
under the same conditions. C-NPC derived from charcoal exhibits high CO2
capacity (1.26 g/g)
at 30 bar, which is 5.7 times higher than Zeolite 5A, 3.4 times higher than
ZIF-8 at the same
conditions. Both of them show much better CO2 uptake amount than their own
precursor. B-PC
shows similar or better CO2 uptake amount compared with asphalt derived porous
carbon or
polymer (polyacrylonitrile or poly[(2-hydroxymethyl)thiophene]) derived porous
carbon (NPC
or SPC) as reported in prior applications.
[299] Figure 28. CO2 uptake performances of different B-PC prepared by
different bases. KOH
treated B-PC exhibits 1.13 g/g CO2 uptake at 30 bar, which is better than NaOH
or LiOH treated
B-PC, which is 0.98 g/g or 0.55 g/g, respectively.
[300] Figure 29. CO2 uptake performances of different B-NPC prepared from
different
precursors using KOH as base. The CO2 uptake amounts of B-PC from mesquite
(450 C),
applewood (450 C), CoolTerraTm, mesquite (700 C), and waste (450 C) are
1.14 g/g, 1.07 g/g,
0.87 g/g, 0.41 g/g, and 0.39 g/g, respectively.
[301] Figure 30. Thermogravimetric analysis (TGA) curves of B-NPC and C-NPC
after H2S
capture. The weight loss of sulfur rich B-NPC and C-NPC is 41% and 6.8%,
respectively. By
calculation, the 112S capture capacity of B-NPC and C-NPC is 0.74 g/g and 0.07
g/g.
[302] Without further elaboration, it is believed that one skilled in the art
can, using the
description herein, utilize the present disclosure to its fullest extent. The
embodiments described
herein are to be construed as illustrative and not as constraining the
remainder of the disclosure
in any way whatsoever. Although the embodiments have been shown and described,
many
variations and modifications thereof can be made by one skilled in the art
without departing from
the spirit and teachings of the invention. Accordingly, the scope of
protection is not limited by
the description set out above, but is only limited by the claims, including
all equivalents of the
subject matter of the claims. The disclosures of all patents, patent
applications and publications
cited herein are hereby incorporated herein by reference, to the extent that
they provide
procedural or other details consistent with and supplementary to those set
forth herein.
59
