Note: Descriptions are shown in the official language in which they were submitted.
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
PROCESSES FOR SELECTIVE NAPHTHA REFORMING
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a PCT International Application which claims the
benefit of and
priority to U.S. Provisional Application Ser. No. 62/549,255 filed August 23,
2017 entitled
"Processes for Selective Naphtha Reforming", U.S. Provisional Application Ser.
No. 62/549,614
filed August 24, 2017 entitled "Systems for Selective Naphtha Reforming", U.S.
Application
Serial No. 16/106,981 filed August 21, 2018 entitled "Processes for Selective
Naphtha
Reforming" and U.S. Application Ser. No. 16/107,010 filed August 21, 2018
entitled "Systems
for Selective Naphtha Reforming" all of which are hereby incorporated by
reference in its
entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
[0002] None.
FIELD OF THE INVENTION
[0003] The present invention relates to processes and systems for upgrading
hydrocarbons
by catalytic reforming.
BACKGROUND
[0004] Known methods for upgrading refinery naphtha streams have inherent
drawbacks.
Feedstock streams mainly comprising hydrocarbons containing four to five
carbon atoms (C4-
05) are typically characterized by high octane ratings, but also high vapor
pressures that exceed
government specifications for liquid transportation fuels such as gasoline.
These specifications
often require either upgrading of the C4 and C5 hydrocarbons to products
characterized by lower
vapor pressure or exclusion from the gasoline pool.
[0005] C6+ naphtha feed streams typically exhibit low vapor pressure, but
are typically also
characterized by a low octane rating and must be upgraded to products
comprising a higher-
octane rating via naphtha reforming. Conventional naphtha reforming
efficiently and selectively
1
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
converts naphthenes (cycloalkanes) into aromatics, but is non-selective for
the conversion of
paraffins to aromatics, resulting in low aromatics yields from paraffins
feeds. Further, C4-05
paraffins are not upgraded in conventional naphtha reformers, since these
paraffins cannot form
aromatics. Thus, while solutions for isolated hydrocarbon streams exist, a
practical process for
efficiently upgrading a naphtha stream comprising both light C4-05
hydrocarbons as well as
C6+ hydrocarbon components currently does not exist.
[0006] Described herein are unique processes and systems that improve the
reforming of a
hydrocarbon feedstock by selectively reforming discrete sub-components of the
feedstock using
at least two structurally-distinct reforming catalysts. Advantages of the
inventive processes and
systems include (but are not limited to) increasing the yield of a liquid
hydrocarbon reformate
that is characterized by at least one of an increased octane rating and
decreased vapor pressure.
A further advantage is a decreased rate of reforming catalyst coking and
deactivation.
BRIEF SUMMARY OF THE DISCLOSURE
[0007] Certain embodiments of the invention comprise A process for
reforming a
hydrocarbon feedstock, comprising: a) providing a hydrocarbon feedstock
comprising paraffins
and naphthenes, each of which comprises from four to twelve carbon atoms,
where the boiling
point range of the hydrocarbon feedstock ranges from about -12 C to about 230
C; b)
separating the hydrocarbon feedstock into a first fraction and a second
fraction, where the first
fraction is enriched in naphthenes relative to the hydrocarbon feedstock, and
the second fraction
is enriched in paraffins relative to the hydrocarbon feedstock; c) contacting
the first fraction with
a first reforming catalyst that comprises a solid support that contains acidic
catalytic sites to
convert the first fraction to a first reformer effluent that is characterized
by increased research
octane number and that is suitable for use as a blend component of a liquid
transportation fuel,
where the contacting is conducted at a temperature, pressure and a hydrogen to
hydrocarbon
ratio that facilitates the catalytic aromatization of naphthenes present in
the first fraction, thereby
producing a first reformer effluent that comprises an increased wt. % of
aromatics relative to the
first fraction and that is characterized by an increased research octane
number relative to the first
fraction, where the temperature is maintained in the range of 480 C or less
to minimize cracking
of naphthenes present in the first fraction, and aromatics present in the
first reformer effluent; d)
2
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
combining the second fraction with a second reforming catalyst that comprises
a solid support
that does not contain acidic catalytic sites to facilitate conversion of
paraffins present in the
second fraction to produce a second reformer effluent suitable for use as a
blend component of a
liquid transportation fuel that predominantly comprises olefins containing
four or five carbon
atoms and unreacted paraffins and that is characterized by an increased
research octane number
relative to the second fraction, where the combining is conducted at a
temperature, a pressure
and a hydrogen to hydrocarbon ratio that facilitates the dehydrogenation of at
least 50% of the
paraffins in the second fraction.
[0008] In certain embodiments, the contacting of c) is conducted at a
temperature in the
range from 445 C to 480 C to minimize cracking of naphthenes present in the
first fraction and
aromatics present in the first reformer effluent. In certain embodiments, the
combining of d) is
conducted at a temperature, a pressure and a hydrogen to hydrocarbon ratio
that facilitates
catalytic dehydrogenation of at least 70 % of the paraffins present in the
second fraction. In
certain embodiments, the hydrogen to hydrocarbon ratio during the contacting
of c) is greater
than 2:1. In certain embodiments, the hydrogen to hydrocarbon ratio during the
combining of d)
is 1:1 or less.
[0009] Certain embodiments additionally comprise contacting the second
reformer effluent
with an oligomerization catalyst at a temperature and a pressure that
facilitates the
oligomerization of olefins in the effluent to larger hydrocarbons that are
characterized by a
decreased Reid vapor pressure and that are suitable for use as a blend
component of a liquid
transportation fuel.
[0010] In certain embodiments, the second reforming catalyst additionally
facilitates the
aromatization of naphthenes present in the second fraction.
[0011] In certain embodiments, a supplemental feed stream comprising light
paraffins
containing four or five carbon atoms is added to the second fraction either
prior to, or concurrent
with the combining of the second fraction with the second reforming catalyst.
[0012] Certain embodiments additionally comprise separating the second
reformer effluent
to produce a light hydrocarbons fraction comprising hydrocarbons containing
from one to four
carbon atoms, and a heavy hydrocarbons fraction comprising hydrocarbon
containing five or
more carbon atoms that is suitable for use as a blend component of liquid
transportation fuel,
wherein the light hydrocarbons fraction is contacted with an oligomerization
catalyst at a
3
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
temperature and a pressure that facilitates the oligomerization of at least a
portion of the light
hydrocarbons fraction to produce larger hydrocarbons that are suitable for use
as a blend
component of liquid transportation fuel.
[0013] Certain embodiments comprise a system for reforming a hydrocarbon
feedstock,
comprising: a) A separation unit operable to receive and separate a
hydrocarbon feedstock
comprising paraffins and naphthenes containing from four to twelve carbon
atoms into a first
fraction that comprises an increased percentage (by weight) of naphthenes
relative to the
hydrocarbon feedstock, and a second fraction that comprises an increased
percentage (by
weight) of paraffins content relative to the hydrocarbon feedstock, where the
hydrocarbon
feedstock is characterized by a boiling point range from about -12 C to about
230 C; b) A first
reforming unit that contains a first reforming catalyst comprising a solid
support that comprises
acidic sites, where the first reforming unit is operable to receive the first
fraction and to facilitate
contact between the first fraction and the first reforming catalyst to convert
the first fraction to a
first reformer effluent that comprises an increased wt. % of aromatics
relative to the first fraction
and is characterized by an increased research octane number, where the first
reforming unit is
operable to maintain conditions comprising a temperature of 480 C or less, a
pressure and a
hydrogen to hydrocarbon ratio that are suitable to facilitate the catalytic
conversion of
naphthenes present in the first fraction by the first reforming catalyst while
minimizing cracking
of naphthenes present in the first fraction and aromatics present in the first
reformer effluent; c)
A second reforming unit that contains a second reforming catalyst comprising a
solid support,
that does not comprise acidic sites, where the second reforming unit is
operable to receive the
second fraction and to combine the second fraction with the second reforming
catalyst to
produce a second reformer effluent, where the combining is conducted at a
temperature, a
pressure and a hydrogen to hydrocarbon ratio that facilitates the
dehydrogenation of at least 50%
of the paraffins present in the second fraction and convert residual
naphthenes present in the
second fraction to aromatics, where the second reformer effluent comprises
predominantly
olefins containing four or five carbon atoms, unreacted paraffins and residual
aromatics, where
the second reformer effluent is characterized by an increased research octane
number relative to
the second fraction.
[0014] Certain embodiments of the system further comprise a distillation
unit operable to
separate the second reformer effluent into a light hydrocarbons fraction
comprising
4
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
hydrocarbons containing one to four carbon atoms, and a heavy hydrocarbons
fraction
comprising hydrocarbons containing five or more carbon atoms.
[0015] Certain embodiments further comprise an oligomerization reactor
containing an
oligomerization catalyst, where the oligomerization reactor is operable to
receive the light
hydrocarbon fraction and facilitate contact between the light hydrocarbon
fraction and the
oligomerization catalyst at a temperature and pressure that are suitable to
facilitate conversion of
the light hydrocarbon fraction to an oligomerization product that is
characterized by a decreased
Reid vapor pressure and that comprises hydrocarbons containing containing six
or more carbon
atoms, that are suitable for use as a blend component of a liquid
transportation fuel.
[0016] In certain embodiments of the system, the second reforming unit is
additionally
operable to receive a supplemental light paraffins stream comprising paraffins
containing four or
five carbon atoms and further operable to facilitate mixing of the
supplemental light paraffins
stream with the second fraction.
[0017] In certain embodiments of the process and/or system, the catalytic
activity of the first
reforming catalyst is characterized as adversely affected by contact with
steam, wherein the
catalytic activity of the second reforming catalyst is characterized as not
adversely affected by
contact with steam.
[0018] In certain embodiments of the process and/or system, the first
reforming catalyst
comprises a solid support selected from zeolite, silica, alumina, chlorided
alumina and fluorided
alumina, and one or more of: 1) at least one metal selected from Group VIM,
Group
Group IIB, Group IIIA and Group IVA of the Periodic Table, and 2) at least one
metal selected
from Pt, Ir, Rh, Re, Sn, Ge and In.
[0019] In certain embodiments of the process and/or system, the second
reforming catalyst
comprises a solid support comprising Group II aluminate spinels according to
the formula
M(A102)2 or MO.A1203, wherein M is a divalent Group IIA or Group II13 metal,
and wherein
the second reforming catalyst further comprises at least one of: 1) a
catalytically-effective
amount of at least one metal from Group VIIIB of the Periodic Table, and 2) at
least one co-
promoter selected from the group consisting of As, Sn, Pb, Ge and Group IA
metals.
[0020] In certain embodiments of the process and/or system, the hydrocarbon
feedstock
comprises at least one of: a refinery raffinate, hydrotreated straight run
naphtha, coker naphtha,
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
hydrocracker naphtha, refinery hydrotreated heavy naphtha, refinery
hydrotreated coker naphtha
and C4+ hydrocarbons derived from natural gas liquids.
[0021] In certain embodiments of the system, the first reforming unit is
operable to receive a
stream of hydrogen and further operable to maintain a hydrogen to hydrocarbon
feedstock ratio
of at least 2:1, wherein the second reforming unit is operable to receive a
stream of hydrogen and
further operable to maintain a hydrogen to hydrocarbon ratio of 1:1 or less.
[0022] In certain embodiments, the hydrocarbon feedstock comprises at least
one of: a
refinery raffinate, hydrotreated straight run naphtha, coker naphtha,
hydrocracker naphtha,
hydrotreated hydrocracker naphtha, refinery hydrotreated heavy naphtha,
refinery hydrotreated
coker naphtha, or C4+ hydrocarbons derived from natural gas liquids. In
certain embodiments,
the boiling point range of the hydrocarbon feedstock ranges from 27 C to
about 230 C,
comprising hydrocarbons that contain from five to twelve carbon atoms. In
certain embodiments,
the boiling point range of the hydrocarbon feedstock ranges from 27 C to
about 185 C,
comprising hydrocarbons that contain from five to ten carbon atoms.
[0023] In certain embodiments, the combining of d) is conducted at a
temperature, a pressure
and a hydrogen to hydrocarbon ratio that facilitates the conversion of at
least 60 wt.%
(optionally, at least 70 wt.%; optionally, at least 80 wt.%) of the paraffins
present in the second
fraction. In certain embodiments, the hydrogen to hydrocarbon ratio during the
contacting of c)
is at least 2:1, optionally at least 4:1. In certain embodiments, the hydrogen
to hydrocarbon ratio
during the combining of d) is 0.7:1 or less; optionally 0.5:1 or less.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] A more complete understanding of the present invention and benefits
thereof may be
acquired by referring to the follow description taken in conjunction with the
accompanying
drawings in which:
[0025] FIG. 1 is a simplified schematic representative of a first
embodiment of the inventive
processes and systems disclosed herein.
[0026] FIG. 2 is a simplified schematic representative of a second
embodiment of the
inventive processes and systems disclosed herein.
6
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
[0027] FIG. 3 is a bar graph that compares the properties of a product
produced by one
embodiment of the present inventive disclosure with the properties of a
product produced by a
convention reforming process.
[0028] FIG. 4 is a bar graph that compares the properties of a product
produced by one
embodiment of the present inventive disclosure with the properties of a
product produced by a
convention reforming process.
[0029] The invention is susceptible to various modifications and
alternative forms, specific
embodiments thereof are shown by way of example in the drawings. The drawings
may not be to
scale. It should be understood that the drawings are not intended to limit the
scope of the
invention to the particular embodiment(s) illustrated.
DETAILED DESCRIPTION
[0030] Disclosed herein are processes and systems for improving the
upgrading of a
hydrocarbon feedstock that selectively reforms the paraffinic and naphthenic
components of the
feedstock by separately reforming each component. The paraffins are reformed
by contact with a
catalyst that is structurally distinct from the catalyst used to reform the
naphthenic hydrocarbons.
Reforming conditions (e.g., temperature, pressure, etc.) are utilized that
maximize the
conversion of each component to products suitable for use as a liquid
transportation fuel (e.g.,
gasoline), or a blend component thereof. When compared to conventional
reforming processes
and systems, the inventive processes and systems disclosed herein may exhibit
one or more of
the following benefits, including increased yield of a liquid reformate
product, improved
properties of a liquid reformate product (e.g., increased octane rating and
decreased vapor
pressure) and decreased rate of reforming catalyst coking and/or deactivation.
[0031] The main objective of catalytic reforming in a refinery setting is
to improve the
octane rating of a hydrocarbon feedstock. This is achieved predominantly by
converting
naphthenes and paraffins in the feedstock to aromatics. Conversion of paraffin
to aromatics
requires more severe process parameters, while the conditions required to
convert naphthenes to
aromatics are relatively mild. Aromatics do not require conversion and are
left unreacted.
Conventional reforming processes often sequentially reform a hydrocarbon
feedstock utilizing
multiple reactors set to operate at increasingly severe conditions. In such
processes, most
naphthenes are converted to aromatics in an initial reactor using mild
conditions, followed by
7
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
paraffin upgrading to aromatics in a subsequent reactor under more severe
conditions. However,
reforming of each component suffers by failure to separate the feedstock or
the intermediate
products (or both).
[0032] In contrast, a first embodiment of the present inventive systems and
processes convey
the entire hydrocarbon feedstock through a first reforming unit containing a
first reforming
catalyst that is maintained under conditions that predominantly convert
naphthenes in the
hydrocarbon feedstock to aromatics, while allowing most paraffins (and,
optionally aromatics)
present in the hydrocarbon feedstock to pass through the first reforming unit
unreacted. The first
reforming unit effluent is separated into a first fraction predominantly
comprising (n- and iso-)
paraffins, and a second fraction comprising predominantly cyclic hydrocarbons
(i.e. mostly
aromatics, with some residual unconverted naphthenes) that is suitable for use
as a blend
component of a liquid transportation fuel (i.e., gasoline). The first fraction
comprising paraffins
is sent to a selective reforming process configured to convert paraffins to
products that are
characterized by higher octane rating and lower vapor pressure, and that are
suitable for use as a
blend component of a liquid transportation fuel.
[0033] Certain alternative embodiments of the present inventive systems and
processes first
split a hydrocarbon feedstock into a first fraction comprising predominantly
paraffins (n-
paraffins and iso-paraffins), and a second fraction predominantly comprising
cyclic
hydrocarbons (predominantly naphthenes and aromatics). The first fraction and
the second
fraction are then each upgraded separately, in separate reforming units
comprising distinct
reforming catalysts.
[0034] Figure 1 depicts a diagram representing a first exemplary embodiment
of the present
inventive processes and systems. A selective reforming system 100 upgrades a
hydrocarbon
feedstock 103 comprising at least paraffins and naphthenes, and optionally
aromatics. The
hydrocarbon feedstock 103 is fed to a first reforming unit 110 that is a
reactor containing at least
a first reforming catalyst 115. The first reforming unit 110 is a reactor
operated at mild
conditions that selectively convert most naphthenes in the hydrocarbon
feedstock 103 to
aromatics, while any aromatics in the hydrocarbon feedstock 103 pass through
the first
reforming unit largely unreacted. Further, the mild conditions (i.e.,
temperature, pressure,
H2:hydrocarbon feed ratio, etc.) maintained in the first reforming unit also
prevent the catalytic
8
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
dehydrogenation, catalytic cracking, or both, of paraffins present in the
hydrocarbon feedstock
103.
[0035] Generally speaking, the reaction conditions maintained within the
first reforming unit
include a temperature in the range from 800 F (454 C) to 1100 F (593 C);
alternatively, in
the range from 850 F (454 C) to 1050 F (565 C); alternatively, in the
range from 900 F (482
C) to 1000 F (538 C). The pressure maintained within the first reforming
unit is in the range
from 3 Bar to 30 Bar, alternatively from 10 Bar to 28 Bar, alternatively from
15 Bar to 28 Bar,
alternatively from 22 Bar to 26 Bar. In certain embodiments, the molar ratio
of hydrogen to
hydrocarbon (H2:HC) at the inlet to the first reforming unit ranges from 2:1
to 15:1,
alternatively, ranges from 3:1 to 8:1, alternatively ranges from 4:1 to 7:1.
[0036] Again, referring to Figure 1, upon entering the first reforming unit
110, the
hydrocarbon feedstock 103 contacts the first reforming catalyst 115, which
catalytically
facilitates conversion of the hydrocarbon feedstock 103 to produce a first
reactor effluent 120
that is characterized by an increased octane rating relative to the feed and a
lower vapor pressure
relative to conventional, 1-step reforming. The first reactor effluent 120 is
conveyed out the first
reforming unit 110 via at least one first reactor outlet 123.
[0037] Generally speaking, the first reforming catalyst comprises at least
one fixed bed of
catalyst that is contained within the first reforming unit. The fixed bed of
catalyst may optionally
be employed in a swing reactor configuration for convenient regeneration of
the catalyst. In
alternative embodiments, the first reforming unit may contain a moving bed,
fluidized bed,
staged fluidized bed or ebullated bed to allow continuous regeneration, or
utilize any other
known catalyst bed configuration that may be advantageously utilized in a
given embodiment.
Such catalyst bed configurations are well-understood in the art, and thus,
will not be discussed
further here.
[0038] Referring again to the embodiment depicted in Figure 1, upon leaving
the first
reforming unit 110, the first reactor effluent 120 is next conveyed to a
separation unit 130 that is
operable to separate cyclic hydrocarbons (i.e., aromatics and at least a
portion of any residual
naphthenes present) from paraffins. Speaking in general terms, the separation
unit may separate
molecules based on solvent extraction (e.g., an aromatic extraction unit),
selective adsorption, or
any other conventional separation technology. For embodiments where the
separation unit
9
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
comprises an aromatics extraction unit, separation is achieved by conventional
processes known
as extractive distillation or extraction.
[0039] Referring again to the embodiment depicted in Figure 1, the
separation unit 130
separates the first reactor effluent 120 into a first fraction 135 that leaves
the separation unit 130
by a first separation unit outlet 138 and a second fraction 140 predominantly
comprising
paraffins that leaves the separation unit 130 via a second separation unit
outlet 143. The first
fraction 135 comprises predominantly aromatics (with some residual unreacted
naphthenes and
paraffins), while the second fraction 140 comprises predominantly paraffins (n-
paraffins and iso-
paraffins) containing six to seven carbon atoms.
[0040] The second fraction 140 is next conveyed to a second reforming unit
150. One
advantage of the present process and system is that separation of cyclic
hydrocarbons from
paraffins by the separation unit 130 significantly decreases the quantity of
aromatics and
naphthenes that enter the second reforming unit 150, which is advantageously
configured to
convert paraffins with increased efficiency in the absence of such naphthenes
and aromatics. In
certain embodiments, the separation unit 130 is operable to exclude > 95 wt.
%, > 98 wt. %, or
even > 99 wt. % of aromatics in the first reactor effluent 120 from the second
fraction 140. The
first fraction 135 may be utilized directly for blending into gasoline or
other liquid transportation
fuel, optionally, subjected to further upgrading prior to blending.
[0041] Again, referring to the embodiment depicted in Figure 1, the second
reforming unit
150 comprises at least a second reforming catalyst 155, which catalytically
facilitates conversion
of the raffinate fraction 140 to a second reactor effluent 160 that leaves the
second reforming
unit via at least one outlet 163. Speaking generally, the reaction conditions
maintained in the
second reforming unit are generally operating conditions suitable for the
steam-stable second
reforming catalyst, including a temperature in the range from 750 F (399 C)
to about 1250 F
(677 C); alternatively, in the range from 850 F (454 C) to 1100 F (593
C); alternatively, in
the range from 900 F (482 C) to 1000 F (538 C). In certain embodiments,
the first reforming
unit is maintained at a reforming temperature that is 480 C or less;
optionally, ranging from
440 C to 485 C; optionally, ranging from 445 C to 480 C; optionally, ranging
from 460 C to
480 C; optionally, ranging from 470 C to 480 C; optionally, ranging from 465 C
to 475 C;
optionally, ranging from 455 C to 470 C. The pressure maintained in the
second reforming unit
is generally in the range from 1 Bar to 34.5 Bar; alternatively, in the range
from 3 Bar to 20 Bar;
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
alternatively, in the range from 2 Bar to 10 Bar; alternatively, in the range
from 2 Bar to 6 Bar.
The molar ratio of hydrogen to hydrocarbon (Hz:HC) maintained inside the
second reforming
unit is within the range from 0 to 1, alternatively from 0.15 to 0.85,
alternatively from 0.3 to 0.7.
The molar water to hydrocarbon ratio (E120:HC) maintained within the second
reforming unit is
in the range from 0.1:1 to 10:1, alternatively in the range from 1:1 to 6:1,
alternatively, in the
range from 2:1 to 6:1. The diluent liquid weight hourly space velocity (grams
per hour of diluent
/ grams catalyst) maintained within the second reforming unit is in the range
from 0.1 to 30,
alternatively in the range from 1:1 to 6:1. The diluent may be, but is not
limited to CO2, H20 (as
steam) or Nz. A low to moderate liquid weight hourly space velocity (LWHSV) is
utilized that is
in the range from 0.5 to 12 hr-1 on a weight hydrocarbon rate per weight
catalyst basis;
alternatively ranging from 2 to 8 hr'; alternatively ranging from 1 to 3 hr-1;
alternatively ranging
from 1.5 to 2.5 hr-1.
[0042] Speaking generally, the second reforming unit is configured to
operate with higher
efficiency when converting a highly paraffinic feedstock (e.g., a highly-
paraffinic AEU
raffinate) rather than a feedstock that comprises a significant percentage of
naphthenes and/or
aromatic hydrocarbons. The conditions and second reformer catalyst that are
utilized in the
second reforming unit cause a feedstock predominantly comprising paraffins to
be efficiently
converted to desired hydrocarbon products (i.e., olefins, iso-olefins,
aromatics, etc.) that are
characterized by an increased octane rating, a decreased vapor pressure, or
both. In all
embodiments, the second reforming catalyst and conditions utilized in the
second reforming unit
are configured to also minimize cracking reactions that produce undesirable
light hydrocarbons
(C1-C4) comprising less than five carbons, as such products are not easily
utilized in liquid
hydrocarbon fuels such as gasoline due to vapor pressure regulations.
[0043] In certain embodiments, the second reforming unit is fed a raffinate
feedstock
produced by an aromatic extraction unit that comprises predominantly n-
paraffins and iso-
paraffins containing 6-7 carbons (C6-C7), and typically less than 15 wt. %
naphthenes and
aromatics (combined weight), alternatively, less than 10 wt. % naphthenes and
aromatics
(combined weight). Certain embodiments mix a co-feed stream of mixed pentane
and/or butanes
with the second fraction. This mixing may occur just upstream from the second
reforming unit,
alternatively, inside the second reforming unit. The co-feed stream may be
derived from a
variety of sources, including, but not limited to, a fraction of natural gas
liquids or condensate.
11
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
In these embodiments, the second reforming unit predominantly converts C5
paraffins to C5
olefins, C6 paraffins to C6 olefins and C7 and larger paraffins (C7+) to C7+
aromatics (e.g.,
alkyl aromatics). In this way, the second reforming unit achieves highly
selective (or
preferential) conversion of C5 paraffins to olefins, while maintaining highly
selective conversion
of C6 and C7 paraffins to higher value products that are suitable for use as a
gasoline blend
component. It is often preferable to selectively convert C6 paraffins to C6
olefins rather than
aromatics, because this decreases production of benzene. Government
regulations strictly limit
the concentration of benzene in the final product gasoline due to toxicity
concerns. However, it
is desirable to maximize the conversion of C7+ paraffins to C7+ aromatics
(i.e., alkyl aromatics)
rather than C7+ olefins, as C7+ aromatic compounds are typically characterized
by higher
octane ratings than comparably-sized olefins. The second reforming unit is
configured to
minimize cracking reactions. However, any light hydrocarbons (C1-C4) that are
present in the
second reformer effluent may optionally be routed to an oligomerization unit
(described in
greater detail below).
[0044] In certain embodiments, the paraffinic feed that is fed to the
second reforming unit
may additionally comprise a supplemental co-feed stream comprising
predominantly pentanes
(optionally, butanes) that is mixed with the second fraction 140 at a location
downstream from
the separation unit 130. In the embodiment depicted in Figure 1, a
supplemental light paraffins
stream 166 is fed directly to the second reforming unit 150, although
alternative embodiments
(not depicted) may mix a light paraffins stream with the second fraction at a
location
immediately upstream from the second reforming unit. The light paraffins
stream may be
derived from a variety of sources in a modern refinery, or may comprise a
fraction derived from
natural gas liquids. Addition of a supplemental light paraffins stream may be
particularly
advantageous in cooler climates or during cooler seasons, when atmospheric
temperatures allow
the blending of smaller olefins into gasoline while still meeting or exceeding
governmental
vapor pressure regulations for the final gasoline product. Alternatively,
light olefins produced by
the second reforming unit may be oligomerized downstream, as will be discussed
in greater
detail below.
[0045] Referring again to the embodiment depicted in Figure 1, the second
reformer effluent
160 is conveyed to a distillation unit 170. The distillation unit 170 operates
in a conventional
manner to separate a light hydrocarbons fraction 180 comprising from one to
four carbons (C1-
12
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
C4) from larger (C5+) hydrocarbons by boiling point. In certain alternative
embodiments, the
distillation unit separates hydrocarbons comprising from one to five carbon
atoms (C1-05) from
hydrocarbons containing six or more carbon atoms (C6+). In the embodiment
depicted in Figure
1, the light hydrocarbons fraction 180 exits the distillation unit 170 through
a first distillation
unit outlet 173 and is conveyed to an oligomerization unit 185 comprising an
oligomerization
catalyst 190. The oligomerization unit 185 operates in a conventional manner
to convert the light
hydrocarbons fraction 180 to larger hydrocarbons 195 that are suitable for use
as a blend
component of liquid transportation fuel, and further, are characterized by a
decreased vapor
pressure. Larger hydrocarbons 195 are directed to a blending unit 198 to be
blended into
gasoline or other liquid transportation fuel.
[0046] The distillation unit 170 further produces a heavy hydrocarbons
fraction 175
comprising hydrocarbons containing five or more carbon atoms that is suitable
for use as a blend
component of a liquid transportation fuel (e.g., gasoline.). The heavy
hydrocarbons fraction 175
exits the distillation unit 170 via a second distillation unit outlet 178 that
may conveyed directly
to a blending unit 198 to be blended into gasoline or other liquid
transportation fuel.
[0047] One advantage of the described processes and systems are that they
increase the
overall product yield of liquid reformate (with decreased light gas formation)
from a given
quantity of hydrocarbon feedstock by selectively reforming the naphthenic
component of the
hydrocarbon feedstock in a first reforming unit (utilizing a first reforming
catalyst), then
separating the product aromatics before selectively reforming the paraffinic
raffinate in a second
reforming unit (utilizing a distinct, second reforming catalyst). This is
achieved (at least in part)
because the first reforming unit is configured to utilize one or more
catalysts and conditions that
efficiently convert naphthenes to high octane, low vapor pressure products
that are well-suited
for blending into gasoline, while simultaneously operating under low severity
conditions that
prevent detrimental cracking of paraffins and allow them to pass through the
first reforming unit
unreacted. The "low severity conditions" may include a temperature in the
first reforming unit
that is decreased by at least 5 C, alternatively, at least 10 C,
alternatively, at least 15 C, while
producing an equivalent or higher overall yield of liquid reformate product
(as compared to a
conventional, one reactor/unit naphtha reforming process that utilizes the
same catalyst). By
lowering reforming temperature, paraffin conversion in the first reforming
unit is decreased to at
least 50%, alternatively at least 40%, alternatively at least 30%,
alternatively at least 20%,
13
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
alternatively at least 10%. We have found that in certain embodiments, there
is a 0.4-0.6%
decrease in paraffin conversion for every 1 F decrease in the temperature
maintained in the first
reforming unit. We also have found that a decrease in the temperature
maintained within the first
reforming unit also typically result in a 0.2-0.3 vol. % increase in liquid
product yield for every 1
F decrease in temperature.
[0048] The "low severity conditions" may further include a high hydrogen to
hydrocarbon
(H2:HC) ratio at the inlet to the first reforming unit that ranges from 2:1 to
15:1, alternatively,
ranges from 3:1 to 8:1, alternatively ranges from 4:1 to 7:1. This ratio
assists in preventing
dehydrogenation of paraffins to olefins, dienes, or other coke precursors in
the first reforming
reactor that can lead to coking of the reforming catalyst, with a consequent
decrease in catalyst
lifespan.
[0049] In certain embodiments, the feedstock is separated prior to
reforming to produce a
naphthenes-enriched first fraction and a paraffins-enriched second fraction.
Although this
separation does not quantitatively separate paraffins from naphthenes, it
excludes a large
quantity of paraffins from the first fraction that is received and upgraded in
the first reforming
unit. In a typical conventional reforming process comprising an acidic naphtha
reforming
catalyst, a significant fraction of these paraffins crack to form light gases
and increase the coking
rate of the first reforming catalyst. Thus, minimizing paraffin content in the
first fraction
beneficially extends the lifespan of the first reforming catalyst.
[0050] Conversely, the second reforming unit is configured to selectively
upgrade the
paraffin-enriched second fraction with increased efficiency and a decreased
rate of coke
formation on the second reforming catalyst (as compared to a reforming process
where the
feedstock to the second reforming unit comprises a significant percentage of
cyclic
hydrocarbons). The second reforming unit is configured to utilize one or more
second reformer
catalyst(s) and conditions that selectively convert the paraffinic feed in the
absence of cyclic
hydrocarbons with high efficiency and decreased rate of coke formation. In
certain
embodiments, the second reforming unit comprises at least one fixed catalyst
bed, which in turn
comprises at least one second reformer catalyst. Such a fixed bed
configuration may be
employed in a swing reactor configuration. In alternative embodiments, the
second reforming
unit may comprise a moving bed, fluidized bed, staged fluidized bed, ebullated
bed, or any other
14
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
configuration deemed advantageous to employ the first reformer catalyst
utilized in a given
embodiment, as is well-understood in the art.
[0051] Typically, the temperature maintained within the second reforming
unit is in the
range from 800 F (484 C) to 1200 F (649 C); alternatively, in the range
from 900 F (484
C) to 1100 F (593 C); alternatively, in the range from 900 F (484 C) to
1000 F (534 C).
The molar ratio of steam to the total feed provided to the second reforming
unit (where total feed
equals the second fraction plus any supplemental light hydrocarbons stream
comprising C4
and/or C5 paraffins) is maintained at a ratio in the range from 2:1 to 19:1
(steam: hydrocarbon
feed); alternatively, a ratio in the range from 2:1 to 6:1; alternatively, a
ratio in the range from
2:1 to 3:1. This ratio is kept constant regardless of the absolute pressure
maintained in the
second reforming unit. A hydrogen co-feed is optionally added to the second
reforming unit at a
hydrogen to hydrocarbon molar ratio that is 1:1 or less; optionally 0.7:1 or
less; optionally, 0.5:1
or less. A low to moderate liquid weight hourly space velocity (LWHSV) is
utilized in the range
from 0.5 to 12 hr-1 on a weight hydrocarbon rate per weight catalyst basis.
[0052] In certain embodiments, the second reforming catalyst contained
within the second
reforming unit converts C5 paraffins to C5 olefins and hydrogen by
dehydrogenation, while
simultaneously minimizing cracking reactions that produce light hydrocarbons
(C1-C4).
Minimizing production of light gases is desirable, as this correlates with
maximizing the yield of
products suitable for use as gasoline or a blend component thereof. Other side
products produced
in the second reforming unit include minor amounts of dienes, and carbon
oxides. In certain
embodiments, a small hydrogenation reactor located downstream from the second
reforming unit
receives and selectively hydrogenates dienes present in the second reformer
effluent to produce a
treated second reformer effluent that is then send to the distillation unit.
Such hydrogenation
processes and systems are conventional, and thus, will not be discussed
further.
[0053] The second reforming unit additionally converts C7 paraffins with
high selectivity to
toluene, with minimal residual production of C7 olefins or cracked products.
Conversion of C7
paraffins primarily to aromatics rather than olefins provides an additional
increase in the octane
rating of the product gasoline, while selective conversion of C4-05 paraffins
to C4-05 olefins
ultimately leads to products characterized by decreased vapor pressure. This
is particularly true
for those embodiments that subsequently oligomerize these C4-05 olefins in an
oligomerization
reactor located downstream from the second reforming unit.
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
[0054] A second embodiment of the inventive processes and systems is
depicted in Figure 2.
A selective reforming system 200 upgrades a hydrocarbon feedstock 205
comprising at least
paraffins and naphthenes, and optionally aromatics. The hydrocarbon feedstock
205 is fed to a
separation unit 210 that separates the hydrocarbon feedstock into a first
fraction 213 comprising
predominantly cyclic hydrocarbons (i.e., naphthenes and C6+ aromatics), and a
second fraction
217 comprising predominantly C2-C12 n-paraffins and iso-paraffins. In certain
embodiments,
the separation unit 210 comprises an aromatic extraction unit or any other
conventional method
for separating cyclic hydrocarbons (i.e., naphthenes and aromatics) from
paraffins. In another
embodiment, the separation unit comprises a sorbent-based separation process.
Such processes
are conventional, and thus, are outside the scope of the present disclosure.
[0055] Following separation, the first fraction and the second fraction are
reformed
separately utilizing two distinct reforming processes. This serves to: 1)
increase the overall yield
of liquid product suitable for use as a gasoline blend stock, as well as, 2)
improve the octane
rating and vapor pressure properties of the combined liquid products from both
reforming
processes. Again, referring to Figure 2, the first fraction 213 leaves the
separation unit 210 by a
first outlet 215 and is conveyed to a first reforming unit 230 that is a
reactor containing at least a
first reforming catalyst 235. The second fraction 217 leaves the separation
unit 210 by a second
outlet 219 and is conveyed to a second reforming unit 240 comprising at least
a second
reforming catalyst 245.
[0056] Generally-speaking, the first reforming unit is operated at
conditions that selectively
convert most of the naphthenes present in the first fraction to aromatics
while minimizing the
undesirable cracking of naphthenes, aromatics and residual paraffins present
in the first fraction.
This allows aromatics to pass through the first reforming unit largely
unreacted. The mild
reaction conditions maintained within the first reforming unit typically
include a temperature in
the range from 750 F (399 C) to 1100 F (593 C); alternatively, in the
range from 800 F
(427 C) to 1050 F (565 C); alternatively, in the range from 850 F (454 C)
to 1050 F (565
C); alternatively, in the range from 900 F (482 C) to 1000 F (538 C). In
certain
embodiments, the first reforming unit is maintained at a reforming temperature
that is 480 C or
less; optionally, ranging from 440 C to 485 C; optionally, ranging from 445 C
to 480 C;
optionally, ranging from 460 C to 480 C; optionally, ranging from 470 C to 480
C; optionally,
ranging from 465 C to 475 C; optionally, ranging from 455 C to 470 C. The
pressure
16
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
maintained within the first reforming unit is in the range from 3 Bar to 30
Bar, alternatively from
Bar to 28 Bar, alternatively from 15 Bar to 28 Bar, alternatively from 22 Bar
to 26 Bar. In
certain embodiments, the molar ratio of hydrogen to hydrocarbon (H2:HC) at the
inlet to the first
reforming unit ranges from 2:1 to 15:1, alternatively, ranges from 3:1 to 8:1,
alternatively ranges
from 4:1 to 7:1.
[0057] Again, referring to the embodiment depicted in Figure 2, upon
entering the first
reforming unit 230, the first fraction 213 contacts the first reforming
catalyst 235, which
catalytically facilitates conversion of the first fraction 213 to produce a
first reactor effluent 255
that characterized by an increased aromatics content and increased octane
rating. The first
reactor effluent 255 is conveyed out the first reforming unit 230 via a first
reactor outlet 257 and
is conveyed directly to blending unit 270 to be blended along with other
refinery product streams
into gasoline or other liquid transportation fuel.
[0058] In general, the first reforming unit contains at least one fixed
catalyst bed. This fixed
catalyst bed may optionally be employed in a swing reactor configuration for
convenient
regeneration of the catalyst. In alternative embodiments, the first reforming
unit may contain a
moving bed, fluidized bed, staged fluidized bed or ebullated bed to allow
periodic, continuous,
or semi-continuous regeneration. Further, the first reforming unit may
comprise any other known
catalyst bed configuration deemed advantageous to implementing the inventive
process. Such
catalyst bed configurations are well-understood in the art, and thus, will not
be discussed further
here.
[0059] Again, referring to the embodiment depicted in Figure 2, the second
fraction 217 is
next conveyed to a second reforming unit 240 that contains a second reforming
catalyst 245.
Upon entering the second reforming unit 240, the second fraction 217 contacts
the second
reforming catalyst 245, which catalytically facilitates conversion of the
first fraction 217 to
produce a second reformer effluent 260 that exits the second reforming unit
240 via second
reactor outlet 263. Within the second reforming unit 240, C4-05 paraffins in
the second fraction
217 are predominantly converted to C4-05 olefins, while C6 paraffins may be
selectively
converted to C6 olefins or benzene, depending on conditions. C7 or larger
paraffins that are
present in the second fraction 217 are predominantly converted to C7+
aromatics. The second
reformer effluent 260 additionally comprises a residual amount of unreacted
paraffins.
17
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
[0060] Referring again to the embodiment depicted in Figure 2, the second
reformer effluent
260 is conveyed to a distillation unit 275. The distillation unit 275 operates
in a conventional
manner to separate a light hydrocarbons fraction 280 comprising from one to
four carbons (C1-
C4) from larger (C5+) hydrocarbons, typically, by boiling point. In certain
alternative
embodiments, the distillation unit separates hydrocarbons comprising from one
to five carbon
atoms (C1-05) from hydrocarbons containing six or more carbon atoms (C6+). In
the
embodiment depicted in Figure 2, the light hydrocarbons fraction 280 exits the
distillation unit
275 through a first distillation unit outlet 282 and is conveyed to an
oligomerization unit 287
comprising an oligomerization catalyst 290. The oligomerization unit 287
operates in a
conventional manner to convert the light hydrocarbons fraction 280 to larger
hydrocarbons 295
that are suitable for use as a blend component of liquid transportation fuel,
and further, are
characterized by a decreased vapor pressure. Larger hydrocarbons 295 are
directed to a blending
unit 270 to be blended into gasoline or other liquid transportation fuel.
[0061] The distillation unit 275 further produces a heavy hydrocarbons
fraction 285
comprising hydrocarbons containing five or more carbon atoms that is suitable
for use as a blend
component of a liquid transportation fuel (e.g., gasoline). The heavy
hydrocarbons fraction 285
exits the distillation unit 275 via a second distillation unit outlet 278 and
is conveyed directly to
blending unit 270 to be blended into gasoline or other liquid transportation
fuel.
[0062] Speaking generally, the reaction conditions maintained in the second
reforming unit
are generally operating conditions that are suitable for the steam-stable
second reforming
catalyst, including a temperature in the range from 750 F (399 C) to about
1250 F (677 C);
alternatively, in the range from 850 F (454 C) to 1100 F (593 C);
alternatively, in the range
from 900 F (482 C) to 1000 F (538 C). The pressure maintained in the
second reforming
unit is generally in the range from 1 Bar to 34.5 Bar; alternatively, in the
range from 3 Bar to 20
Bar; alternatively, in the range from 2 Bar to 10 Bar; alternatively, in the
range from 3 Bar to 7
Bar. The molar ratio of hydrogen to hydrocarbon (H2:HC) maintained inside the
second
reforming unit is within the range from 0 to 1, alternatively from 0.15 to
0.85, alternatively from
0.3 to 0.7, alternatively, 0.7:1 or less, alternatively 0.5:1 or less. The
molar water to hydrocarbon
ratio (H20:HC) maintained within the second reforming unit is in the range
from 0.1:1 to 10:1,
alternatively in the range from 1:1 to 6:1, alternatively, in the range from
2:1 to 6:1. The diluent
liquid weight hourly space velocity (grams per hour of diluent per grams
catalyst) maintained
18
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
within the second reforming unit is in the range from 0.1 to 30, alternatively
in the range from
1:1 to 6:1. The diluent may be, but is not limited to CO2, H20 (as steam) or
Nz. A low to
moderate liquid weight hourly space velocity (LWHSV) is utilized that is in
the range from 0.5
to 12 hr' on a weight hydrocarbon rate per weight catalyst basis;
alternatively ranging from 2 to
8 hr'; alternatively ranging from 1 to 3 hr-1; alternatively ranging from 1.5
to 2.5 hr-1.
[0063] An additional advantage of the inventive processes and systems is
that separation of
aromatic hydrocarbons from paraffins by the separation unit significantly
decreases the quantity
of aromatics that enter the second reforming unit (SRU), which is beneficial
because the lifespan
of the second reforming catalyst is extended in the absence of such naphthenes
and aromatics,
and further, the second reforming catalyst converts paraffins with increased
efficiency in the
absence of naphthenes and aromatics. In certain embodiments, >95 %, >98 %, or
even >99 % of
aromatics are separated from the hydrocarbon feedstock in the separation unit
to form at least a
portion of the first fraction (and thereby prevented from entering the second
reforming unit).
[0064] Speaking generally, the second reforming unit is configured to
operate with higher
efficiency when converting a highly paraffinic feedstock (e.g., a highly-
paraffinic AEU
raffinate) rather than a feedstock that comprises a significant percentage of
naphthenes and/or
aromatic hydrocarbons. The conditions maintained in the second reforming unit
and the second
reformer catalyst that is utilized together cause a feedstock predominantly
comprising paraffins
to be efficiently converted to desired hydrocarbon products (i.e., olefins,
iso-olefins, aromatics,
etc.) that are characterized by an increased octane rating and decreased vapor
pressure (relative
to a conventional one-step reforming process. In general, far less cracking
occurs in the second
reforming unit than the first reforming unit, in part due to the decreased
(alternatively, total lack
of) acidity of the second reforming catalyst relative to the first reforming
catalyst. This is
beneficial because cracking leads to increased production of light
hydrocarbons (C1-C4)
comprising four or less carbons. Such products cannot be easily blended into
liquid hydrocarbon
fuels due to their high vapor pressures.
[0065] In certain embodiments, the second fraction comprises predominantly
n-paraffins and
iso-paraffins containing 6-12 carbons (C6-C12), and less than about 10 wt. %
naphthenes and
aromatics (combined), alternatively less than about 5 wt. % naphthenes and
aromatics
(combined). In these embodiments, the second reforming unit predominantly
converts C5
paraffins to C5 olefins, C6 paraffins to C6 olefins (alternatively, aromatics)
and C7 and larger
19
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
paraffins (C7+) to C7+ aromatics (e.g., alkyl aromatics). In this way, the
second reforming unit
achieves highly selective conversion of C5 paraffins to olefins, while
maintaining high
selectivity conversion of C6 and C7 paraffins to higher value products that
are suitable for use as
a gasoline blend component. The presence of non-reactive diluent in the second
reforming unit
increases the conversion of C5-C6 paraffins beyond that typically observed for
non-diluent
containing dehydrogenation systems. It is often preferable to selectively
convert C6 paraffins to
C6 olefins rather than aromatics, because this decreases production of
benzene. Government
regulations strictly limit the concentration of benzene in the final product
gasoline due to toxicity
concerns. However, it is desirable to maximize the conversion of C7+ paraffins
to C7+
aromatics (i.e., alkyl aromatics) rather than C7+ olefins, as C7+ aromatic
compounds are
typically characterized by higher octane ratings than comparably-sized
olefins.
[0066] In certain embodiments, the paraffinic feed that is fed to the
second reforming unit
may additionally comprise a supplemental co-feed stream comprising
predominantly pentanes
(optionally, butanes) that is mixed with the second fraction at a location
downstream from the
separation unit. In the embodiment depicted in Figure 2, a supplemental light
paraffins stream
266 is fed directly to the second reforming unit 240, although alternative
embodiments (not
depicted) may mix a light paraffins stream with the second fraction at a
location immediately
upstream from the second reforming unit. The light paraffins stream 266 may be
derived from a
variety of sources in a modern refinery, or may comprise a fraction derived
from natural gas
liquids. Addition of a supplemental light paraffins stream may be particularly
advantageous in
cooler climates or during cooler seasons, when atmospheric temperatures allow
the blending of
smaller olefins into gasoline while still meeting or exceeding governmental
vapor pressure
regulations for the final gasoline product. Alternatively, light olefins
produced by the second
reforming unit may be oligomerized downstream, as will be discussed in greater
detail below.
[0067] Referring again to the embodiment depicted in Figure 2, after
leaving the second
reforming unit 240, the second reformer effluent 260 is next conveyed to a
distillation unit 275
that utilizes a conventional separation technology (e.g., distillation) for
separating (C1-C4) light
hydrocarbons 280 from larger C5+ hydrocarbons 285 that are suitable for
conveying to blending
unit 270 to be blended along with other refinery product streams into gasoline
or other liquid
transportation fuel. Commercial fuel blending is well-understood in the field,
and therefore, will
not be discussed further here.
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
[0068] The second reformer effluent 260 is conveyed to distillation unit
275. In certain
alternative embodiments, the distillation unit 275 separates C1-05
hydrocarbons from C6+
hydrocarbons. In the embodiment depicted in Figure 2, a C1-C4 hydrocarbon
fraction 280 exits
the fractionation unit 275 through a first distillation unit outlet 282 and is
conveyed to an
oligomerization unit 287 comprising an oligomerization catalyst 290. The
oligomerization unit
287 oligomerizes the C 1-C4 hydrocarbon fraction 280 in a conventional manner
to produce an
oligomerization product 295 that comprises larger C5+ hydrocarbons and is
characterized by
decreased vapor pressure relative to the C-1-C4 hydrocarbon fraction 280. The
oligomerization
product 295 is conveyed to blending unit 270 to be blended along with other
refinery product
streams into gasoline or other liquid transportation fuel. The distillation
unit 275 additionally
produces a (C5+) hydrocarbons fraction 285 that exits the distillation unit
275 via a second
distillation unit outlet 278 and is conveyed to blending unit 270 to be
blended along with other
refinery product streams into gasoline or other liquid transportation fuel.
[0069] In certain embodiments (described above), the hydrocarbon feedstock
is first
separated to produce a paraffin-enriched fraction and a naphthene-enriched
fraction prior to
reforming. While this separation does not quantitatively separate paraffins
from naphthenes, it
allows the naphthenes-enriched fraction to be reformed in a first reforming
unit that is
specifically-designed for reforming naphthenes in the absence of paraffins.
Meanwhile,
separation of the hydrocarbon feedstock also produces a second, paraffin-
enriched fraction that
is reformed in a second reforming unit that is specifically-designed for
reforming paraffins in the
absence of cyclic hydrocarbons. As a result, both the first and second
reforming units operate
more efficiently. The first reforming unit operates more efficiently with a
feedstock that
excludes most paraffins because paraffins, particularly those with less than
eight carbons, are
prone to significant detrimental cracking in the first reforming unit to form
light gases, rather
than higher-value liquid-range products that are suitable for use as a
gasoline blend component.
[0070] Conversely, the second reforming unit is configured to utilize one
or more second
reformer catalyst(s) and maintain reaction conditions that facilitate
selective upgrading of a
paraffin-enriched fraction with increased efficiency and a decreased rate of
coke formation on
the second reforming catalyst (compared to a conventional reforming process
that typically
upgrades a hydrocarbon feedstock additionally comprising a significant
percentage of
naphthenes and/or aromatics).
21
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
[0071] Overall, separately reforming naphthenic vs paraffinic fractions of
a hydrocarbon
feedstock according to the inventive processes disclosed herein increases the
overall combined
liquid product yield, and decreases (C1-C4) light gas formation from a given
quantity of
hydrocarbon feedstock. The process also produces a liquid reformate product
characterized by
improved properties of increased octane rating and decreased vapor pressure.
[0072] In certain embodiments, the first reforming unit contains a catalyst
bed or multiple
catalyst beds, each comprising one or more reforming catalysts, where the
first reforming unit is
maintained at operating conditions that achieve increased liquid product yield
of reformate
(compared to conventional reforming processes) at a reforming temperature that
is decreased by
at least 5 C, alternatively at least 8 C, alternatively at least 10 C
relative to the temperature
that is maintained in a the reforming unit of a conventional single-reactor
reforming process that
upgrades a hydrocarbon feedstock comprising both cyclic hydrocarbons and
paraffinic
hydrocarbons. In certain embodiments, the first reforming unit is maintained
at a reforming
temperature that is 480 C or less; optionally, ranging from 440 C to 485 C;
optionally, ranging
from 445 C to 480 C; optionally, ranging from 460 C to 480 C; optionally,
ranging from 470 C
to 480 C; optionally, ranging from 465 C to 475 C; optionally, ranging from
455 C to 470 C.
Decreasing the operating temperature maintained within the first reforming
unit by at least 5 C
(relative to the temperature typically maintained in a conventional, one step
reforming unit) not
only saves on system operating costs, but decreases the deactivation rate of
the first reforming
catalyst. In contrast, the feedstock and operating conditions utilized in a
typical conventional
reforming unit are generally believed to expose the first reforming catalyst
to significant
concentrations of olefins and dienes at a temperature that increases the rate
of coke formation on
the reforming catalyst, with a consequent decrease in catalyst lifespan.
[0073] In certain embodiments, the second reforming unit comprises at least
one fixed
catalyst bed, which in turn comprises at least one second reformer catalyst.
Embodiments that
utilize a fixed bed configuration may optionally be employed in a swing
reactor configuration. In
alternative embodiments, the second reforming unit may comprise a moving bed,
fluidized bed,
staged fluidized bed, ebullated bed, or any other configuration deemed
advantageous to employ
the first reformer catalyst utilized in a given embodiment, as is well-
understood in the art.
[0074] The second reforming catalyst contained within the second reforming
unit converts
C4-05 paraffins to olefins by dehydrogenation, while simultaneously minimizing
cracking
22
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
reactions that produce light hydrocarbons (C1-C4) that cannot be utilized as a
blend component
of a liquid transportation fuel. Minimizing production of light hydrocarbons
is desirable, as this
correlates inversely with the conversion to products characterized by
increased octane rating and
decreased vapor pressure, and that are suitable for use as a liquid
transportation fuel blend
component. Embodiments that subsequently oligomerize these C4-05 olefins in an
oligomerization reactor located downstream from the second reforming unit
assist in further
improving the properties of the liquid reformate product, but the additional
improvement is
generally minor in most embodiments, relative to the improvement provided by
the inventive
process.
[0075] In these same embodiments, the second reforming catalyst contained
within the
second reforming unit converts C7 paraffins in the feed to toluene. This
conversion is highly
selective, with minimal residual conversion to C7 olefins or cracked products.
Conversion of C7
paraffins primarily to aromatics rather than olefins or cracked products
provides an additional
increase in the octane rating of the liquid reformate product.
[0076] In certain embodiments, a small hydrogenation reactor located
downstream from the
second reforming unit receives and selectively hydrogenates dienes present in
the second
reformer effluent to produce a treated second reformer effluent that is then
sent to the distillation
unit. Such hydrogenation processes and systems are conventional, and thus,
will not be discussed
further.
[0077] In all embodiments, the first and second reforming catalysts are
materially-different
catalysts that are derived from mutually-exclusive subsets of reforming
catalysts. The first
reforming catalyst functions to more-efficiently reform naphthenic
hydrocarbons to aromatic
compounds characterized by a higher-octane rating and/or lower vapor pressure,
while the
second reforming catalyst functions to more-efficiently reform heavy
paraffinic (n- and iso-)
hydrocarbons to aromatic compounds characterized by a higher octane rating
and/or lower vapor
pressure, and light paraffinic hydrocarbons to olefins suitable for blending
or further upgrading.
[0078] The first reforming catalyst is generally a conventional naphtha
reforming catalyst
that is well-suited for reforming naphthenes to aromatics. Such catalysts are
bi-functional
catalysts consisting of a catalytically effective amount of one or more
metal(s) or metal oxide(s)
impregnated on a support, including, but is not limited to, alumina, chlorided
alumina, fluorided
alumina, modified zeolites and carbon. The support is generally unsuitable for
reforming in the
23
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
presence of water or steam, and catalytic activity degrades rapidly in the
presence of steam. The
impregnated metal(s) generally catalyze hydrogenation and dehydrogenation
reactions, while the
support often (but not always) comprises acidic sites and promotes
isomerization and cyclization
reactions. Sulfur and nitrogen impurities in the feed are highly detrimental
to the function of the
first reforming catalyst at levels above about 1 ppm (typically). Sulfur
deactivates metal sites,
reducing dehydrogenation, while nitrogen can deactivate acid sites, reducing
isomerization and
cyclization. Modification of the catalytic function is sometimes achieved by
impregnating a
second or third metal onto the support, which serves to decrease the rate of
coking. In certain
embodiments, the first reforming catalyst comprises at least one metal
selected from Group
VIM, Group VIBB, Group IIB, Group IIIA or Group IVA of the Periodic Table. In
certain
embodiments, the first reforming catalyst comprises a metal such as Pt, Ir,
Rh, Re, Sn, Ge, In, or
combinations of two or even three of these metals. Many such metal
combinations have been
well-characterized in the field as suitable for naphtha reforming.
[0079] The support of the first reforming catalyst is generally
characterized by a
significantly higher acidity than the support of the second reforming
catalyst. It is important to
note that the acidic support of the first reforming catalyst is rapidly
degraded in the presence of
steam, and therefore is unsuitable for steam-reforming applications.
Furthermore, the second
reforming catalyst is resistant to sulfur and nitrogen contaminants in the
feed, and in some
embodiments retains catalytic activity in the presence of as much as 100 ppm
of sulfur and
nitrogen. These are among the major differences that distinguish the first
reforming catalyst from
the second reforming catalyst in the present inventive processes and systems.
[0080] The second reforming catalyst can be generally described as
structurally-stable in the
presence of steam, and is generally much less sensitive to the presence of
sulfur and nitrogen
contaminants in the feedstock (as compared to the first reforming catalyst)
typically being able
to withstand up to 100 ppm of either sulfur or nitrogen without adversely
affecting catalytic
activity. The second reforming catalyst further comprises a catalytically-
effective amount of at
least one metal from Group VIII of the Periodic Table, including Ru, Pt, Pd,
Os, Ir, Ni, Rh and
combinations thereof In certain embodiments, the second reforming catalyst is
composed of a
solid support selected from Group II aluminate spinels, or mixtures thereof,
impregnated with a
catalytically-effective amount (i.e., at least about 0.01 percent by weight,
and preferably from
about 0.1 percent to about 10 percent by weight, based on the weight of the
support) of at least
24
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
one of the Group VIII metals listed above; and, optionally, up to about 10 wt.
% (based on the
weight of the support), of a co-promoter material selected from the group
consisting of tin, lead,
germanium, Group IA metals, and combinations thereof Group II aluminate
spinels are
compounds of the formula M(A102)2 or MO.A1203, wherein M is a divalent Group
IIA or Group
BB metal (e.g., Zn, Mg, Be, Ca).
[0081] The processes and systems described herein provide the advantage of
extending
catalyst lifespan of both the first and second reforming catalysts by exposing
each catalyst to
only a fraction of the total hydrocarbon feedstock. Due to the lessening or
absence of feed
paraffins, the first reforming unit can operate at a lower severity (defined
as a lower weight-
averaged inlet temperature, or WAIT) than a conventional reformer and achieve
the same RON
and improved liquid yield. This lower WAIT also results in a decreased coking
rate and an
extended useful lifespan for the reforming catalyst contained within the first
reforming unit. This
is possibly due to reduced formation of olefins and dienes on the catalyst
surface. Alternatively,
the first reforming unit in this embodiment can operate at a higher severity
and, due to the
improved feed quality, will achieve the same liquid yield as a conventional
reformer but achieve
significantly higher octane reformate. The first reforming unit is exposed to
less olefins and
dienes, which it is generally hypothesized contributes to a decreased coking
rate and an extended
useful lifespan for the reforming catalyst contained within the first
reforming unit.
[0082] The lifespan of the second reforming catalyst is extended by
exposure to less
naphthenes and aromatics, which can cause premature coking of the second
reforming catalyst.
Further, removing cyclic hydrocarbons from the feedstock fraction that is fed
to the second
reforming catalyst allows the conditions utilized in the second reforming unit
to be tailored for
maximizing the conversion of paraffins to higher value olefins and aromatics
(characterized by
increased octane rating and decreased vapor pressure) that are useful as
liquid transportation fuel
blend stock.
[0083] The hydrocarbon feedstock may comprise, for example, (but not
limited to) a refinery
stream including at least one of: a refinery raffinate, hydrotreated straight
run naphtha, coker
naphtha, hydrocracker naphtha (either pre- or post-hydrotreating), refinery
hydrotreated heavy
naphtha, refinery hydrotreated coker naphtha, isomerate (pre or post-
hydrotreating) comprising
hydrocarbons containing from four to six carbons, and hydrocarbons containing
four or more
carbons that are derived from natural gas liquids. In embodiments where C6
hydrocarbons are
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
present in the hydrocarbon feedstock, any benzene in the product reformate may
be alkylated in
a later step prior to sending the reformate to a blending unit. As previously
mentioned, the
process may be extended to include C4 paraffins; in this case the C4 paraffins
are selectively
converted to C4 olefins, then optimally oligomerized to larger hydrocarbons.
[0084] A typical hydrocarbon feedstock for the inventive processes and
systems will
generally comprise both cyclic hydrocarbons and paraffinic hydrocarbons, as
the improvement
provided by the process increases the overall yield and quality of the
reformate product obtained
from feeds that are not exclusively either paraffinic or aromatic/naphthenic
in composition. The
feedstock comprises hydrocarbons and may be characterized by several
established parameters
for measuring feedstock quality, such as the boiling point range and the
content of naphthenes
(N) and aromatics (A) (as defined by the expression: N + 2A). The feedstock
may be also
characterized by percentage of hydrocarbons in the feedstock that comprise a
given number of
carbon atoms. Typically, the hydrocarbon feedstock comprises hydrocarbons
containing four to
twelve carbon atoms (C4-C12) characterized by a boiling point range from -12
C to about 230
C; alternatively, the hydrocarbon feedstock comprises hydrocarbons containing
five to twelve
carbon atoms (C5-C12) characterized by a boiling point range from about 27 C
to about 230
C; alternatively, the hydrocarbon feedstock comprises hydrocarbons containing
five to ten
carbon atoms (C5-C10) characterized by a boiling point range from about 27 C
to about 185
C; alternatively, the hydrocarbon feedstock comprises hydrocarbons containing
five to nine
carbon atoms (C5-C9) characterized by a boiling point range from about 27 C
to about 160 C.
[0085] In a conventional reforming unit, the quality of the feedstock (as
indicated by N+2A)
dictates operating parameters for reforming to achieve desired yield and/or
increase in octane
rating. A higher N+2A value indicates the feed is rich in Naphthenes and
Aromatics, which is
important because a feedstock comprising a larger percentage of naphthenes and
aromatics
requires less severe reforming process conditions to achieve a given octane
rating improvement
than a feedstock that comprises a larger percentage of paraffins. The N + 2A
value for a
hydrocarbon feedstock suitable for use with the present inventive systems and
processes may
range from as low as 35 to 85, alternatively, in the range from 45 to 85,
alternatively, in the
range from 55 to 85. The first fraction that is fed to the first reforming
unit (in the second
embodiment only) is enriched for naphthenes and aromatics, and is
characterized by a N + 2A
value that may range from 40 to 140, alternatively, in the range from 50 to
140, alternatively, in
26
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
the range from 60 to 140, alternatively, in the range from 70 to 140,
alternatively, in the range
from 80 to 140.
EXAMPLES
[0086] The following examples are provided to help illustrate the
innovation encompassed
within the inventive processes and systems described herein. However, the
scope of the
invention is not intended to be limited to the embodiments or examples that
are specifically
disclosed. Instead, the scope is intended to be as broad as is supported by
the complete
specification and the appending claims.
EXAMPLE 1:
[0087] Table 1 demonstrates the advantage to converting a highly paraffinic
feedstock to by
a reforming catalyst that is selective for reforming paraffins (corresponding
to the second
reforming catalyst described herein). A feedstock comprising 90 wt % C5 and C7
paraffins was
fed to a reactor maintained at a temperature of 1020 F (549 C), a reactor
pressure of 68 psig, a
liquid weight hourly space velocity of 4.2 hr-1, a Hz:hydrocarbon ratio of 0.5
(mol/mol), and a
H20:HC ratio of 3 (mol/mol). The catalyst utilized was a steam reforming
catalyst comprising
zinc-aluminate spinel impregnated with platinum metal. The first column of
Table 1 shows the
molecular composition of the paraffinic feedstock (where P =paraffins, N =
naphthenes, 0 =
olefins, D = dienes and A= aromatics) in wt. %., while the second column shows
the molecular
composition of the reformed product. The results show that 37.5 wt. % of the
feed was
converted to aromatics (with minimal benzene production) while 16.3 wt. % of
the feed was
converted to olefins. The research octane rating (RON) of the product was
improved by 37.6,
while the liquid product yield was nearly 84.3 vol. %.
Table 1: Composition of a paraffinic feedstock and a liquid reformate product
derived from
reforming the feedstock with a catalyst that is selective for reforming
paraffins in the absence of
cyclic hydrocarbons.
Composition Feed wt.% Product wt.%
H2 1.1 2.5
CO + CO2 0.0 1.3
Cl-C4 0.0 3.1
P5 29.4 14.7
27
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
N5 0.0 0.2
05 (n + i + cyclo) 0.0 5.2
D5 0.0 0.2
P6 0.0 0.6
N6 0.5 0.4
06 (n + i + cyclo) 0.0 0.8
D6 0.0 0.6
A6 0.0 1.0
P7 60.2 15.8
N7 5.3 1.1
07 (n + i + cyclo) 1.1 11.3
D7 0.0 1.3
A7 2.1 38.7
C8+ 0.2 0.7
Other 0.0 0.6
C5+ RON 59.3 96.9
C5+ (vol%) 84.3
EXAMPLE 2:
[0088] Computer-based modeling was conducted to estimate both the liquid
product yield
and the product properties resulting from implementing the first embodiment of
the inventive
processes and systems, as generally depicted in the diagram of Figure 1. In
this embodiment, the
first reforming unit (FRU) containing a naphtha reforming catalyst (first
reforming catalyst)
comprising an alumina support impregnated with platinum was operated at
relatively mild
temperature conditions that would predominantly convert naphthenes in the
hydrocarbon
feedstock to aromatics without significant cracking activity, thus allowing
paraffins in the
hydrocarbon feedstock to pass through the first reforming unit mostly
unreacted. Separation of a
paraffin-enriched fraction from the first reformer effluent by a separator
(SEP) was modeled as
occurring in an aromatic extraction unit, based upon publicly-available
empirical data. The
calculated paraffinic fraction (from the first reactor effluent) was then
modeled as feedstock for a
second reforming unit (SRU) comprising a steam-active reforming catalyst
comprising a zinc
aluminate support and impregnated with platinum and tin.
[0089] A kinetic model based on existing empirical data was utilized to
calculate C5+
reformate yield, product RVP, and WAIT (weight averaged inlet temperature) for
the first
reforming unit as a function of pressure, feed quality (N + 2A), the desired
product octane rating
(RON), space velocity and feed composition. Two feed streams comprised the
hydrocarbon
28
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
feedstock for this example: a mixed pentanes stream (9 vol% of total) routed
directly to second
reforming unit (to mix with the second fraction), and a heavy naphtha (91 vol%
of total), sent to
the first reforming unit.
[0090] A correlative model based on empirical data was used to predict the
C5+ liquid yield
from the second reforming unit based on product research octane number (RON).
The relative
sizes of the separated first and second fractions were calculated using a
known correlation
between reformate octane rating and the quantity of aromatics in the stream.
The change in Reid
Vapor Pressure (RVP) of the light hydrocarbon fraction fed to the
oligomerization unit (see
Figure 1, item 180) was estimated using empirical data from a typical light
FCC naphtha feed,
which is about 1 psia (0.07 bar). RON of the combined products of the first
and second
reforming units was calculated using volumetric linear octane blending, while
combined product
RVP was calculated using a commercially-available vapor pressure blending
index.
[0091] To demonstrate the advantages of this embodiment of the inventive
processes and
systems, the inventive process is compared to a conventional reforming process
that comprises a
single-step reforming utilizing a conventional naphtha reforming catalyst
(alumina impregnated
with Pt). Calculated feedstock molecular composition and properties, operating
conditions,
estimated product yield, and product properties are listed for the
conventional process (Column
2), and the inventive process (Column 3). In this example, liquid reformate
product yield (i.e.,
C5+ reformate) was the independent variable. Operating conditions were
utilized for each
process that would be expected to yield of 65 vol % of C5+ liquid reformate
product.
Table 2: Conditions required for conventional reforming process (Column 2) and
inventive
embodiment 1 (Column 3) to produce an equivalent yield of liquid reformate
product.
Base Case FRU-SEP-
Process Parameter (FRU) SRU
Separator pressure (bar) 17.6
Feed N + 2A (vol%) 53 53
Feed P + I (vol%) 61 61
FRU Feed N (vol%) 26 26
Feed A (vol%) 13 13
LWHSV (hr-1) 0.8 0.8
H2 recycle/feed rate (mscf/bbl) 8.0 8.0
_________ Inlet H20/HC (mol/mol) 0 0
29
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
First reactor inlet press. (bar) 26.2 26.2
WAIT* ( C) 492 481
Product RON 98.3 93.9
Liq. Product Yield (vol%) 60.9 66.9
Feed P + I (vol%) 94
Feed N (vol%) 4
Feed A (vol%) 1
Inlet H2/HC (mol/mol) 0.5
SRU Inlet H20/HC (mol/mol) 3
Inlet pressure (bar) 5.7
Average Bed temperature ( C) 532
LWHSV (hr-1) 2
Product RON 89.2
Liq. Product Yield (vol%) 85.5
Product RON 94.5 104.7
Final
Liq. Product Yield (vol%) 65 65
Product
Product RVP (bar) 0.42 0.30
* Weight-averaged inlet temperature
Table 2 demonstrates that using the operating conditions required for each
process (conventional
versus inventive) to produce a liquid product yield (of C5+ reformate) equal
to 65 vol. %, the
inventive process produced a product characterized by a significantly
increased RON (104.7
versus 94.5) and a significantly decreased vapor pressure (4.3 versus 6.1
psia) versus the product
of a conventional reforming process. These results are visualized in the bar
graph shown in
Figure 3.
EXAMPLE 3:
[0092] Computer-based modeling was conducted to estimate both the liquid
product yield
and the product properties resulting from implementing the second embodiment
of the inventive
processes and systems, as generally depicted in the diagram of Figure 2,
particularly with
regards to increased product yield and improved product properties. In this
experiment, the
hydrocarbon feedstock was first separated in a separator (SEP) comprising an
aromatic
extraction unit to produce a naphthenes/aromatics-enriched first fraction, and
a paraffins-
enriched second fraction.
[0093] The naphthenes/aromatics-enriched first fraction was modeled as
feedstock for
upgrading in a first reforming unit (FRU) containing a naphtha reforming
catalyst (first
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
reforming catalyst) comprising an alumina support impregnated with platinum.
The first
reforming unit was operated at relatively mild temperature (decreased by 11 C
relative to the
conventional reforming process shown in column 3 of Table 3) that would
predominantly
convert naphthenes to aromatics without significant cracking activity, and
further would
decrease the rate of catalyst coking (relative to operating at a higher
temperature). Meanwhile,
the separated paraffins-enriched second fraction was modeled as feedstock for
a second
reforming unit containing a commercially-available steam-active reforming
catalyst comprising
a zinc aluminate support impregnated with platinum.
[0094] A kinetic model based on existing empirical data was utilized to
calculate C5+
reformate yield, product RVP, and WAIT (weight averaged inlet temperature) for
the first
reforming unit as a function of pressure, feed quality (defined by the
equation: N + 2A), the
desired product research octane number (RON), space velocity and feed
composition. Two feed
streams comprised the hydrocarbon feedstock for this example: a mixed pentanes
stream (9
vol.% of total) routed directly to a second reforming unit (to mix with the
second fraction), and a
heavy naphtha (91 vol.% of total), which was fed to the separation unit as a
first process step,
prior to routing the naphthenes-enriched first fraction to the first reforming
unit and a paraffins-
enriched second fraction to the second reforming unit.
[0095] A correlative model based on empirical data (RON 40 - 100) was used
to predict the
C5+ liquid yield from the second reforming unit based on product RON. The
change in Reid
Vapor Pressure (RVP) of the oligomerization feed stream was estimated using
empirical data
from a typical light FCC naphtha feed, which is about 1 psia (0.07 bar). RON
of the combined
products of the first and second reforming units was calculated using
volumetric linear octane
blending, while combined product RVP was calculated using the a commercially-
available vapor
pressure blending index.
[0096] To demonstrate the advantages of this embodiment of the inventive
processes and
systems, the inventive process was compared to a conventional reforming
process that comprises
a single-step reforming utilizing a conventional naphtha reforming catalyst
(alumina
impregnated with Pt). Calculated feedstock molecular composition and
properties, operating
conditions, estimated product yield, and product properties are listed for the
conventional
process (Column 3), and the inventive process (Column 4). In this example, RON
was the
31
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
independent variable. Operating conditions were utilized for each process that
would be
expected to produce a liquid product characterized by a RON of 95Ø
Table 3: Conditions required to produce a liquid reformate product
characterized by an
equivalent octane rating (RON = 95.0) for a conventional one-step reforming
process (Column
3) and a second inventive embodiment (Column 4) illustrated by the schematic
diagram of
Figure 2.
Base Case SEP with
Process Parameter (CRU Only) FRU / SRU
SEP Inlet pressure (bar) 17.6
Feed N + 2A (vol%) 51.8 74.8
Feed P + I (vol%) 61.3 44.2
Feed N (vol%) 25.6 36.9
Feed A (vol%) 13.1 18.9
LWHSV (hr-1) 0.8 0.8
FRU FRU H2 Recycle/feed rate 8.0 8.0
FRU Inlet H20/HC (mol/mol) 0 0
FRU Inlet pressure (bar) 26.2 26.2
WAIT* ( C) 491 480
Product RON 98.2 96.2
Liq. Product Yield (vol%) 73.5 84.8
Feed P + I (vol%) 100
Feed N (vol%) 0
Feed A (vol%) 0
Inlet H2/HC (mol/mol) 0.5
SRU Inlet H20/HC (mol/mol) 3
SRU Inlet pressure (bar) 5.7
Average Bed temperature ( C) 578
LWHSV (hr-1) 4
Product RON 100
Liq. Product Yield (vol%) 66.4
Product RON 95 95
Final
Liq. Product Yield (vol%) 75.9 80.8
Product
Product RVP (bar) 0.40 0.34
* Weight-averaged inlet temperature
Table 3 demonstrates that at the operating conditions required for each
process (conventional
versus inventive) to produce a liquid reformate product characterized by a RON
of 95, the
32
CA 03073502 2020-02-20
WO 2019/040487 PCT/US2018/047319
inventive process produced a significantly larger yield of liquid reformate
product (80.8 vol. %
versus 75.9 vol.%) and the liquid reformate product was characterized by a
significantly
decreased RVP (0.40 for base case versus 0.34 bar for the inventive case).
These results are
visualized in the bar graph shown in Figure 4.
DEFINITIONS
[0097] As used herein, the term "octane rating" refers to "research octane
number" (RON),
calculated by a well-established process for indicating the antiknock
properties of a fuel based
on a comparison with a mixture of isooctane and heptane.
[0098] In closing, it should be noted that each claim listed below is
hereby incorporated into
this specification as an additional embodiment of the inventive disclosure. It
should be
understood that various changes, substitutions, and alterations can be made to
the invention as
described herein without departing from the spirit and scope of the invention
as defined by the
claims appended below. Those skilled in the art may be able to study the
description and identify
obvious variants and equivalents of the invention that are not exactly as
described herein. It is
the intent of the inventors that obvious variants and equivalents of the
invention are within the
scope of the claims appended below. Further, the description, abstract and
drawings are not
intended to limit the scope of the invention narrower than the full scope
provided by the claims.
33
