Note: Descriptions are shown in the official language in which they were submitted.
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CATALYTIC CARBON FIBER PREPARATION METHODS
BACKGROUND
[0001] Chemical processes often require multiple unit operations to produce a
product
stream. A particular unit operation may be a liquid-liquid contacting
operation whereby two liquids
are brought into intimate contact to effectuate mass transfer between the
liquids, a reaction between
components in the liquids, or both. Another unit operation may be a gas-liquid
contacting operation
whereby a gas and a liquid are brought in contact to effectuate mass transfer
between the liquids,
a reaction between components in the liquids, or both. Liquid-liquid
contacting may be beneficial
in some types of chemical reactions where one reactant is miscible in a first
liquid but immiscible
in a second liquid. An example of such a reaction may be where a first
reactant is present in a polar
solvent such as water and a second reactant is present in a non-polar solvent
such as a hydrocarbon
and the water and hydrocarbon are immiscible. Liquid-liquid contacting may
have other
applications such as liquid-liquid extraction whereby a species present in a
first liquid is extracted
into a second liquid by mass transfer across the liquid-liquid interface. Gas-
liquid contacting may
be beneficial in some types of chemical reactions where a component in the gas
phase is to be
reacted with a component in the liquid phase of where a gaseous component is
absorbed into the
liquid phase.
[0002] A particular challenge of liquid-liquid contactors and gas-liquid
contactors,
collectively referred to as "mass transfer devices", may be ensuring adequate
contact area between
phases such that the mass transfer or reactions may occur in an appreciable
amount and in an
economically viable manner. In general, liquid-liquid contacting operations
may be performed
with immiscible liquids, such as, for example, an aqueous liquid and an
organic liquid. Using two
immiscible liquids may allow the liquids to be readily separated after the
liquid-liquid contacting
is completed. However, when a liquid-liquid contacting operation is performed
with immiscible
liquids, phase separation may occur before adequate contact between the
liquids is achieved.
[0003] Several mass transfer devices and techniques have been developed to
enhance the
contact area between phases, including, but not limited to, fiber-bundle type
contactors. A fiber-
bundle type contactor may generally comprise one or more fiber bundles
suspended within a shell
and two or more inlets where the phases, including gas-liquid or liquid-
liquid, may be introduced
into the shell. The fiber bundle may promote contact between the phases by
allowing a first phase
to flow along individual fibers of the fiber bundles and a second phase to
flow between the
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individual fibers thereby increasing the effective contact area between the
phases. The two phases
may flow from an inlet section of the shell to an outlet section of the shell
while maintaining
intimate contact such that a reaction, mass transfer, or both may be
maintained between the two
phases.
[0004] Fiber-bundle type contactors have been developed to teat rnercaptan
sulfur
containing hydrocarbon streams. In these contactors, a liquid catalyst or
solid catalyst bed may be
utilized in conjunction with caustic to convert mercaptan sulfur to disulfide
oil. However, there
exist challenges in this process including ensuring that the extent of
reaction is sufficient to such
that the resultant product stream is on specification. Some methods to ensure
that the extent of
reaction are sufficient to produce a product stream that is on specification
may be to design the
mass transfer device to have longer contact time by building the mass transfer
device physically
larger or to design the mass transfer device with features that enhance mixing
from entrance
effects. While physical features of the mass transfer device may be optimized
to some degree,
there may be limitations to the extent to which a reaction may proceed
regardless of the physical
configuration of the mass transfer device because of limitations of the
oxidation catalyst.
SUMMARY
[0005] Disclosed herein is an example method including: oxidizing a virgin
carbon fiber
to produce an oxidized carbon fiber; reacting the oxidized carbon fiber with a
polyamine
compound to produce an amine modified carbon fiber; and reacting the amine
modified carbon
fiber with an organometallic macrocycle to produce the catalytic carbon fiber.
[0006] Further disclosed herein is an example method including: providing a
carbon fiber
and an aminated macrocycle, mixing the carbon fiber and the aminated
macrocycle with a solvent;
and reacting the carbon fiber and the aminated macrocycle to form an amide
bond between the
carbon fiber and the aminated macrocycle thereby forming the catalytic carbon
fiber.
[0007] Further disclosed herein is a fiber bundle contactor including: a flow
path defined
by a conduit; a catalytic carbon fiber bundle disposed in the conduit, wherein
the catalytic carbon
fiber comprises an amine compound covalently bonded to the carbon fiber, and
an organornetallic
macrocycle covalently bonded to the amine compound; and an inlet allowing
fluid flow into the
flow path.
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[0008] Further disclosed herein is a method including: introducing into vessel
a
hydrocarbon comprising mercaptan sulfur, an aqueous caustic solution, and an
oxidizer; reacting
at least a portion of the mercaptan sulfur and the aqueous caustic solution to
produce a mercaptide;
and reacting the mercaptide and the oxidizer in the presence of a catalytic
carbon fiber bundle to
produce a disulfide oil, wherein the catalytic carbon fiber bundle comprises a
carbon fiber, an
amine compound covalently linked to the carbon fiber, and an organometallic
macrocycle
covalently linked to the amine compound.
[0009] These and other features and attributes of the disclosed processes and
systems of
the present disclosure and their advantageous applications and/or uses will be
apparent from the
detailed description which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] These drawings illustrate certain aspects of some of the embodiments of
the present
disclosure, and should not be used to limit or define the disclosure.
[0011] FIG. 1 is an illustrative depiction of a block flow diagram of a
process for producing
disulfide oil from a hydrocarbon stream containing mercaptan sulfur.
[0012] FIG. 2 is an illustrative depiction if a hydrocarbon desulfurization
vessel containing
catalytic carbon fibers.
[0013] FIG. 3 is an illustrative depiction if a hydrocarbon desulfurization
vessel containing
catalytic carbon fibers.
[0014] FIG. 4 is an illustrative depiction if a standalone caustic
regeneration unit
containing catalytic carbon fibers.
[0015] FIG. 5a is an illustrative depiction if a standalone caustic
regeneration unit
containing catalytic carbon fibers
[0016] FIG. 5b is an illustrative depiction if a top view of a distributor
tray.
DETAILED DESCRIPTION
[0017] The present disclosure may relate to liquid-liquid and gas-liquid mass
transfer
devices, and in some embodiments, to mass transfer devices comprising
catalytic carbon fibers.
Catalytic carbon fibers may comprise an organometallic catalyst that has been
chemically grafted
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onto a surface of a carbon fiber. The catalytic carbon fiber may be used as a
heterogeneous catalyst
in the liquid-liquid and gas-liquid mass transfer devices.
[0018] Disclosed herein are methods of preparing catalytic carbon fibers. In
some
embodiments, methods of preparing catalytic carbon fibers may include a
process comprising
oxidizing a virgin carbon fiber to produce an oxidized carbon fiber followed
by amine treatment
to produce an amine modified carbon fiber. The amine modified carbon fiber may
be further
reacted with an organometallic macrocycle to produce the catalytic carbon
fibers. In some
embodiments, methods of preparing catalytic carbon fibers may include reacting
an aminated
macrocycle with carbon fiber in the presence of a solvent to produce the
catalytic carbon fibers.
[0019] Any type of carbon fiber may be utilized in the present disclosure
including, but
not limited to, carbon fibers prepared using polyacrylonitrile (PAN),
mesophase pitch, and rayon.
Suitable carbon fibers may have any structural ordering including those carbon
fibers classified as
turbostratic or graphitic or any structural ordering therebetween. Carbon
fibers may be of any
quality including from about 50% carbon by weight to about 100% carbon by
weight any may
have any classification such as low modulus carbon fiber having a tensile
strength modulus below
240 million kPa, intermediate modulus carbon fiber having a tensile strength
modulus of about
240 million kPa to 500 million kPa, or high tensile strength modulus carbon
fiber having a tensile
strength modulus of about 500 million-1.0 billion kPa. Carbon fibers may have
any diameter
including from about 5 micrometers to about 20 micrometers, or any diameters
therebetween.
Carbon fibers may be in the form of yarns or bundles whereby several hundred
to several thousand
individual carbon fibers may be spun together to form the carbon fiber yarn or
carbon fiber bundle.
[0020] In some embodiments, methods of preparing catalytic carbon fibers, a
first step may
include oxidizing a virgin carbon fiber to produce an oxidized carbon fiber.
Oxidation may be
carried out in a liquid or gas environment to form oxygen-containing
functional groups on the
surface of the carbon fiber. Oxygen-containing functional groups may include
carboxyl, carbonyl,
lactone, and hydroxyl which are covalently bonded to at least a portion of the
carbon atoms making
up the carbon fiber. The step of oxidizing may oxidize the carbon fiber to any
suitable extent.
Without limitation, the carbon fiber may be oxidized to include about 0.1 wt.%
to about 25 wt.%
oxygen-containing functional groups. Alternatively, the carbon fiber may be
oxidized to include
about 0.1 wt.% to about 1 wt.% oxygen-containing functional groups, about 1
wt.% to about 5
wt.% oxygen-containing functional groups, about 5 wt.% to about 10 wt.% oxygen-
containing
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functional groups, about 10 wt.% to about 15 wt.% oxygen-containing functional
groups, about 15
wt.% to about 20 wt.% oxygen-containing functional groups, about 20 wt.% to
about 25 wt.%
oxygen-containing functional groups, or any ranges therebetween. The degree of
oxidation may
be utilized to control the final concentration organometallic macrocycle
dispersed on the catalytic
carbon fiber which may in turn directly affect the overall catalytic activity
of the catalytic carbon
fiber.
[0021] Oxidation of the carbon fiber may be achieved by submersing the virgin
carbon
fiber in an acid and allowing the acid to react with the virgin carbon fiber.
Suitable acids may
include mineral acids such as hydrochloric acid, nitric acid, phosphoric acid,
sulfuric acid, boric
acid, hydrofluoric acid, hydrobromic acid, perchloric acid, hydroiodic acid,
fluoroantimonic acid,
carborane acids, fluoroboric acid, fluorosulfuric acid, hydrogen fluoride,
triflic acid, and perchloric
acid for example organic acids such as acetic acid, formic acid, citric acid,
oxalic acid, and tartaric
acid, for example. In addition to, or alternatively to oxidation using acids,
the oxidation step may
also be performed using plasma treatment in oxygen atmosphere, gamma radiation
treatment,
electrochemical oxidation using a an oxidant such as sodium hydroxide,
ammonium hydrogen
carbonate, ammonium carbonate, sulfuric acid, or nitric acid, or oxidation by
potassium persulfate
with sodium hydroxide or silver nitrate. The acidic oxidation may be performed
at any temperature
in the range of about 0 C to 150 C. Alternatively, the oxidation may be
performed in a range of
0 C to about 25 C, about 25 C to about 50 C, about 50 C to about 75 C,
about 75 C to about
100 C, about 100 C to about 125 C, about 125 C to about 150 C or any
temperature ranges
therebetween. Oxidation may be performed for any period of time suitable for
achieving a desired
concentration of oxygen-containing functional groups on the carbon fibers. The
time required to
achieve a specified concentration of oxygen-containing functional groups may
be dependent upon
many factors including identity and concentration of the acid and temperature
conditions selected.
In general, the oxidation may be carried out for a period of time ranging from
about 1 hour to about
24 hours. Alternatively, the oxidation may be carried out in a time ranging
from about 1 hour to
about 3 hours, about 3 hours to about 6 hours, about 6 hours to about 9 hours,
about 9 hours to
about 12 hour, about 12 hours to about 15 hours, about 15 hours to about 18
hours, about 18 hours
to about 21 hours, about 21 hours to about 24 hours, or any ranges
therebetween. After oxidation
by acid treatment, the oxidized carbon fibers may optionally be washed using
water or other
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solvent to remove excess acid. The oxidized carbon fibers may be dried at
elevated temperature
after washing to remove water or solvent used in the washing step.
[0022] A second step in preparing the catalytic carbon fibers may include
producing an
amine modified carbon fiber. After the oxidized carbon fibers are produced,
the oxidized carbon
fibers may be reacted with an amine containing compound to produce the amine
modified carbon
fiber. The amine containing compound may be any polyamine compound containing
at least two
amine groups including diamines, triamines, and higher order amines. The amine
containing
compound may include linear, branched, or cyclic primary or secondary amines,
with carbon
ranging numbers from C2-C20. Some specific amine containing compounds may
include, without
limitation, ethylenediamine, propane-1,3-diamine, butane-1,4-diamine, pentane-
1,5-diamine,
hexamethylenediamine, diethylenetriamine, benzene-1,3,5-triamine, and
combinations thereof.
The oxidized carbon fibers may be reacted with the amine containing compound
at any suitable
conditions, including at a temperature in the range of about 0 C to 250 C.
Alternatively, the
oxidation may be performed in a range of 0 C to about 25 C, about 25 C to
about 50 C, about
50 C to about 75 C, about 75 C to about 100 C, about 100 C to about 125
C, about 125 C
to about 150 C, about 150 C to about 175 C, about 175 C to about 200 C,
about 200 C to
about 225 C, about 225 C to about 250 C or any temperature ranges
therebetween. The time
required for reacting the oxidized carbon fibers and amine containing compound
may be dependent
upon many factors including identity of the amine containing compound and
temperature
conditions selected. In general, the oxidized carbon fibers may be reacted
with the amine
containing compound for a period of time ranging from about 1 hour to about 24
hours.
Alternatively, the oxidized carbon fibers may be carried out in a time ranging
from about 1 hour
to about 3 hours, about 3 hours to about 6 hours, about 6 hours to about 9
hours, about 9 hours to
about 12 hours, about 12 hours to about 15 hours, about 15 hours to about 18
hours, about 18 hours
to about 21 hours, about 21 hours to about 24 hours, or any ranges
therebetween. After the amine
reaction, the amine modified carbon fibers may optionally be washed using
water or other solvent
to remove excess amine. The amine modified carbon fibers may be dried at
elevated temperature
after washing to remove water or solvent used in the washing step.
[0023] A third step in preparing the catalytic carbon fibers may include
reacting the amine
modified carbon fibers with an organometallic macrocycle to produce the
catalytic carbon fiber.
Organometallic macrocycles may include unsubstituted metal phthalocyanines,
substituted metal
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phthalocyanines, and combinations thereof. Substituted metal phthalocyanine
may include
substitutions of halogens, hydroxyl, amine, alkyl, aryl, thiol, alkoxy,
nitrosyl groups, or
combinations thereof, at one or more peripheral hydrogen atoms on the metal
phthalocyanine.
Metal phthalocyanines may include any suitable metal including, without
limitation, vanadium
(V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc
(Zn), ruthenium (Ru),
rhodium (Rh), palladium (Pd), silver (Ag), and combinations thereof. The
organometallic
macrocycle may be dispersed in a solvent including, but not limited to water,
pyridine, DMSO,
DMF, THF, ethanol, acetonitrile, chloroform, ethylene glycol, methanol,
benzene, or combinations
thereof prior to reacting with the amine modified carbon fibers.
[0024] The amine modified carbon fibers may be reacted with the organometallic
macrocycle at any suitable conditions, including at a temperature in the range
of about 0 C to 150
C. Alternatively, the oxidation may be performed in a range of 0 C to about
25 C, about 25 C
to about 50 C, about 50 C to about 75 C, about 75 C to about 100 C, about
100 C to about
125 C, about 125 C to about 150 C or any temperature ranges therebetween.
The time required
for reacting the amine modified carbon fibers and amine containing compound
may be dependent
upon many factors including identity of the organometallic macrocycle and
temperature conditions
selected. In general, the amine modified carbon fibers may be reacted with the
organometallic
macrocycle for a period of time ranging from about 1 hour to about 24 hours.
Alternatively, the
oxidation may be carried out in a time ranging from about 1 hour to about 3
hours, about 3 hours
to about 6 hours, about 6 hours to about 9 hours, about 9 hours to about 12
hour, about 12 hours
to about 15 hours, about 15 hours to about 18 hours, about 18 hours to about
21 hours, about 21
hours to about 24 hours, or any ranges therebetween. After the organometallic
macrocycle
reaction, the catalytic carbon fiber may optionally be washed using water or
other solvent to
remove excess organometallic macrocycle. The catalytic carbon fiber may be
dried at elevated
temperature after washing to remove water or solvent used in the washing step.
[0025] In further embodiments, a synthesis method for producing catalytic
carbon fibers
may include reacting an aminated macrocycle with carbon fiber in the presence
of a solvent to
produce the catalytic carbon fibers. The aminated macrocycle may comprise an
organometallic
macrocycle and amine group grafted to the organometallic macrocycle. The amine
group may
include an amino group, and imino group, or combinations thereof. The amine
group allows the
aminated macrocycle to react with oxygen-containing groups such as carboxylic
groups on the
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surface of the carbon fiber to form an amide bond between the arninated
macrocycle and the carbon
fiber. Carbon fiber production may include oxidative surface treatment steps
described above that
leave oxygen containing groups such as carboxylic groups on the surface of the
carbon fiber. The
concentration of oxygen containing groups such as carboxylic groups may
determine the amount
of aminated macrocycle that may be reacted with the carbon fiber. Further
oxidative surface
treatments may be utilized to increase the concentration of reactive groups,
including carboxylic
groups, such that the carbon fiber may react with greater amounts of aminated
macrocycle.
[0026] The aminated macrocycle may include any suitable organometallic
macrocycle,
including, but not limited to, unsubstituted metal phthalocyanines,
substituted metal
phthalocyanines, and combinations thereof Substituted metal phthalocyanine may
include
substitutions of halogens, hydroxyl, alkyl, aryl, thiol, alkoxy, nitrosyl
groups, or combinations
thereof, at one or more peripheral hydrogen atoms on the metal phthalocyanine.
Metal
phthalocyanines may include any suitable metal including, without limitation,
vanadium (V),
manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn),
ruthenium (Ru),
rhodium (Rh), palladium (Pd), silver (Ag), and combinations thereof. The
aminated macrocycle
may include one or more amine groups (-NH2 or -NH) grafted to the
organometallic macrocycle.
The aminated macrocycle may include an amine containing compound grafted to
the organic
macrocycle. The amine containing compounds may include C2-C20, monoamines,
diamines,
triamines, and higher order amines. The amine containing compound may include
linear, branched,
or cyclic amines. Some specific amine containing compounds may include,
without limitation,
ethylenediamine, propane-1,3-diamine, butane-1,4-
diamine, pentane-1,5-diamine,
hexamethylenediamine, diethylenetri amine, benzene-1,3,5-triamine, and
combinations thereof.
Some suitable aminated macrocycles may include amino cobalt phthalocyanines
such as mono
amino cobalt phthalocyanines and poly amino cobalt phthalocyanines. Poly amino
cobalt
phthalocyanines may include di-amino cobalt phthalocyanine, tri-amino cobalt
phthalocyanines,
tetra-amino cobalt phthalocyanines, and higher order poly amino cobalt
phthalocyanines. Other
specific suitable aminated macrocycles may include porphyrins, hemes, polyaza
compounds, and
crown ethers.
[0027] Catalytic carbon fibers may be prepared by reacting an aminated
macrocycle with
carbon fiber to form an amide bond between the aminated macrocycle. There are
several synthesis
methods for formation of an amide bond between the carbon fiber and the
aminated macrocycle,
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only some of which may be disclosed herein. One synthesis method may include
direct formation
of the amide bond by reacting the carbon fiber and aminated macrocycle at
elevated temperature
in a suitable solvent. Another synthesis method may include amide formation
via the generation
of acyl chlorides from carboxylic acids with chlorinating agents such as
thionyl chloride. Another
synthesis method may include amide formation using a coupling agent such as
carbodiimide or
benzotriazole. Another synthesis method may include enzyme catalyzed amide
formation.
[0028] In the direct amide bond synthesis, carbon fiber and aminated
macrocycle may be
combined in a solvent and heated thereby forming an amide bond between the
carbon fiber and
aminated macrocycle to produce the catalytic carbon fiber. Some suitable
solvents may include,
but are not limited to pyridine, DMSO, DMF, THF, ethanol, acetonitrile,
chloroform, ethylene
glycol, methanol, benzene, and combinations thereof The carbon fibers may be
reacted with the
aminated macrocycle at any suitable conditions, including at a temperature in
the range of about
100 C to 200 C. Alternatively, the reaction may be performed in a range of
100 C to about 125
C, about 125 C to about 150 C, about 150 C to about 175 C, about 175 C to
about 200 C,
or any temperature ranges therebetween. The time required for reacting the
carbon fibers and
aminated macrocycle may be dependent upon many factors including identity of
the aminated
macrocycle and temperature conditions selected. In general, the carbon fibers
may be reacted with
the aminated macrocycle for a period of time ranging from about 1 hour to
about 24 hours or
longer. Alternatively, the reaction may be carried out in a time ranging from
about 1 hour to about
3 hours, about 3 hours to about 6 hours, about 6 hours to about 9 hours, about
9 hours to about 12
hours, about 12 hours to about 15 hours, about 15 hours to about 18 hours,
about 18 hours to about
21 hours, about 21 hours to about 24 hours, or any ranges therebetween. After
the aminated
macrocycle reaction, the catalytic carbon fiber may optionally be washed using
water or other
solvent to remove excess aminated macrocycle. The catalytic carbon fiber may
be dried at elevated
temperature after washing to remove water or solvent used in the washing step.
[0029] In the acyl chloride synthesis, carbon fiber may be combined with a
chlorinating
agent such as thionyl chloride, phosphorous trichloride, or terephthaloyl
chloride, and heated. The
chlorinating agent may react with oxygen containing groups, such as carboxylic
groups, on the
carbon fiber to produce acyl chloride on the carbon fiber. The carbon fibers
may be reacted with
the chlorinating agent at any suitable conditions below the boiling point of
the chlorinating agent,
including at a temperature in the range of about 0 C to 150 C.
Alternatively, the reaction may be
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performed in a range of 0 C to about 25 C, about 25 C to about 50 C, about
50 C to about 75
C, about 75 C to about 100 C, about 100 C to about 125 C, about 125 C to
about 150 C or
any temperature ranges therebetween. In general, the carbon fibers may be
reacted with the
chlorinating agent for a period of time ranging from about 1 hour to about 24
hours or longer. The
chlorinating agent modified carbon fibers may be reacted with an aminated
macrocycle to produce
a catalytic carbon fiber. For example, the chlorinating agent modified carbon
fibers and aminated
macrocycle may be combined in a solvent and heated thereby forming an amine
bond between the
carbon fiber and aminated macrocycle to produce the catalytic carbon fiber.
Some suitable solvents
may include, but are not limited to water, pyridine, DMSO, DMF, Tiff, ethanol,
acetonitrile,
chloroform, ethylene glycol, methanol, benzene, and combinations thereof. The
chlorinating agent
modified carbon fibers may be reacted with the aminated macrocycle at any
suitable conditions,
including at a temperature in the range of about 0 C to 150 C.
Alternatively, the reaction may be
performed in a range of 0 C to about 25 C, about 25 C to about 50 C, about
50 C to about 75
C, about 75 C to about 100 C, about 100 C to about 125 C, about 125 C to
about 150 C or
any temperature ranges therebetween. The time required for reacting the
chlorinating agent
modified carbon fibers and aminated macrocycle may be dependent upon many
factors including
identity of the aminated macrocycle and temperature conditions selected. In
general, the
chlorinating agent modified carbon fibers may be reacted with the aminated
macrocycle for a
period of time ranging from about 1 hour to about 24 hours or longer.
Alternatively, the reaction
may be carried out in a time ranging from about 1 hour to about 3 hours, about
3 hours to about 6
hours, about 6 hours to about 9 hours, about 9 hours to about 12 hour, about
12 hours to about 15
hours, about 15 hours to about 18 hours, about 18 hours to about 21 hours,
about 21 hours to about
24 hours, or any ranges therebetween. After the aminated macrocycle reaction,
the catalytic carbon
fiber may optionally be washed using water or other solvent to remove excess
aminated
macrocycle. The catalytic carbon fiber may be dried at elevated temperature
after washing to
remove water or solvent used in the washing step.
[0030] Another synthesis method may include amide formation using a coupling
agent. In
this method, carbon fiber and a coupling agent may be combined in a suitable
solvent and heated.
The coupling agent may react with oxygen-containing functional groups on the
carbon fiber or
with the carbon fiber to form a functionalized carbon fiber. Some suitable
coupling agents may
include, but are not limited to carbodiimide, benzotriazole, and combinations
thereof. The
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functionalized carbon fiber may be combined with an aminated macrocycle and
solvent which may
react to form the catalytic carbon fiber. Some suitable solvents may include,
but are not limited to
water, pyridine, DMSO, DMF, THF, ethanol, acetonitrile, chloroform, ethylene
glycol, methanol,
benzene, and combinations thereof. The functionalized carbon fiber may be
reacted with the
aminated macrocycle at any suitable conditions, including at a temperature in
the range of about 0
C to 150 C. Alternatively, the reaction may be performed in a range of 0 C
to about 25 C, about
25 C to about 50 C, about 50 C to about 75 C, about 75 C to about 100 C,
about 100 C to
about 125 C, about 125 C to about 150 C or any temperature ranges
therebetween. The time
required for reacting the functionalized carbon fiber and aminated macrocycle
may be dependent
upon many factors including identity of the aminated macrocycle and
temperature conditions
selected. In general, the functionalized carbon fiber may be reacted with the
aminated macrocycle
for a period of time ranging from about 1 hour to about 24 hours or longer.
Alternatively, the
reaction may be carried out in a time ranging from about 1 hour to about 3
hours, about 3 hours to
about 6 hours, about 6 hours to about 9 hours, about 9 hours to about 12 hour,
about 12 hours to
about 15 hours, about 15 hours to about 18 hours, about 18 hours to about 21
hours, about 21 hours
to about 24 hours, or any ranges therebetween. After the aminated macrocycle
reaction, the
catalytic carbon fiber may optionally be washed using water or other solvent
to remove excess
aminated macrocycle. The catalytic carbon fiber may be dried at elevated
temperature after
washing to remove water or solvent used in the washing step.
[0031] Another synthesis method may include amide formation using an enzyme.
Enzymatic catalysis may allow for the amination reaction to occur at
relatively lower temperatures
which may allow for a broader solvent compatibility. In this method, carbon
fiber and aminated
macrocycle may be combined in a in a suitable solvent with an enzyme. The
enzyme may include
any enzyme capable of catalyzing the formation of an amide bond between the
carbon fiber and
the animated macrocycle. Some examples of suitable enzymes may include, but
are not limited to,
proteases, subtili sin, acylases, amidases lipases, and combinations thereof.
Some suitable solvents
may include, but are not limited to water, pyridine, DMSO, DMF, THF, ethanol,
acetonitrile,
chloroform, ethylene glycol, methanol, benzene, and combinations thereof. The
carbon fiber may
be reacted with the aminated macrocycle at any suitable conditions, including
at a temperature in
the range of about 0 C to 100 C. Alternatively, the reaction may be
performed in a range of 0 C
to about 25 C, about 25 C to about 50 C, about 50 C to about 75 C, about
75 C to about 100
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or any temperature ranges therebetween. The time required for reacting the
carbon fiber and
aminated macrocycle may be dependent upon many factors including identity of
the aminated
macrocycle and temperature conditions selected. In general, the carbon fiber
may be reacted with
the aminated macrocycle for a period of time ranging from about 1 hour to
about 24 hours or
longer. Alternatively, the reaction may be carried out in a time ranging from
about 1 hour to about
3 hours, about 3 hours to about 6 hours, about 6 hours to about 9 hours, about
9 hours to about 12
hour, about 12 hours to about 15 hours, about 15 hours to about 18 hours,
about 18 hours to about
21 hours, about 21 hours to about 24 hours, or any ranges therebetween. After
the aminated
macrocycle reaction, the catalytic carbon fiber may optionally be washed using
water or other
solvent to remove excess aminated macrocycle. The catalytic carbon fiber may
be dried at elevated
temperature after washing to remove water or solvent used in the washing step.
[0032] Once the catalytic carbon fibers have been synthesized as described
above, the
catalytic carbon fibers may be further processed by shaping the catalytic
carbon fibers. For
example, individual strands of the catalytic carbon fibers may be drawn
together and secured to
form a catalytic carbon fiber bundle. The catalytic carbon fiber bundle may be
utilized in a reactor
to form a reaction zone within the reactor. Additional processing of the
carbon fibers may include
reducing the size of the carbon fibers to produce a catalytic carbon fiber
suitable for fluidization,
for example within a fluidized bed reactor, or may be pelletized or otherwise
made suitable for use
in a packed bed reactor.
[0033] Hydrocarbon streams in refineries and chemical plants often contain
unwanted
contaminants such as organically bound sulfur compounds, carboxylic acids, and
hydrogen sulfide.
Product specifications may call for the reduction and/or removal of these
contaminants during the
refining process. Organically bound sulfur, such as mercaptan sulfur, may be
present in some
hydrocarbon streams within a refinery or chemical plant. It may be desirable
to reduce the
mercaptan sulfur content of a hydrocarbon stream to produce a product stream
with reduced
mercaptan sulfur content. There are generally two options for treating
mercaptan sulfur containing
streams. Mercaptan extraction may be utilized whereby the mercaptan sulfur is
reacted with a
caustic stream to produce an organo-sulfur compound such as a mercaptide, A
portion of the
mercaptide may dissolve in the aqueous portion of the caustic stream thereby
removing the
mercaptan sulfur from the hydrocarbon stream. In general, the solubility of
the organo-sulfur
compound is a function of the hydrocarbon chain length whereby relatively
lower molecular
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weight mercaptans may produce a more soluble product when reacted with the
caustic stream and
relatively higher molecular weight mercaptans may produce a relatively less
soluble product when
reacted with the caustic stream. The organo-sulfur compound may be further
oxidized to disulfide
oil by reacting the organo-sulfur compound with oxygen in the presence of a
catalyst. For some
hydrocarbon streams containing heavier mercaptan sulfur containing compounds,
mercaptan
sweetening may be utilized to directly convert the mercaptan sulfur to the
disulfide oil by reacting
the mercaptan sulfur with oxygen in the presence of a catalyst. Sweetening
directly to disulfide oil
may be preferable in some hydrocarbon streams where the organo-sulfur
compounds produced
would be relatively insoluble in the aqueous portion of the caustic stream.
Some operations may
involve extraction and sweetening in series whereby a mixed hydrocarbon stream
containing a
portion of relatively lower molecular weight mercaptan sulfur and a relatively
higher molecular
weight mercaptan sulfur are contacted with a caustic stream followed by
oxidation to produce
disulfide oil. Such operations may occur in separate units or as an integrated
process within a single
vessel. An example of single vessel extraction/oxidation us the Mericat II
process available from
Merichem Company.
[0034] There may be a wide variety of hydrocarbon streams which contain
contaminants
that may be removed. While the present application may only disclose
embodiments with regards
to some specific hydrocarbon streams, the disclosure herein may be readily
applied to other
hydrocarbon streams not specifically enumerated herein. The caustic treatment
process may be
appropriate for treatment of any hydrocarbon feed including, but not limited
to, hydrocarbons such
as alkanes, alkenes, alkynes, and aromatics, for example. The hydrocarbons may
comprise
hydrocarbons of any chain length, for example, from about C3 to about C30, or
greater, and may
comprise any amount of branching. Some exemplary hydrocarbon feeds may
include, but are not
limited to, crude oil, propane, LPG, butane, light naphtha, isomerate, heavy
naphtha, reformate,
jet fuel, kerosene, diesel oil, hydro treated distillate, heavy vacuum gas
oil, light vacuum gas oil,
gas oil, coker gas oil, alkylates, fuel oils, light cycle oils, and
combinations thereof. Some non-
limiting examples of hydrocarbon streams may include crude oil distillation
unit streams such as
light naphtha, heavy naphtha, jet fuel, and kerosene, fluidized catalytic
cracker or resid catalytic
cracker gasoline, or RCC, natural gasoline from NGL fractionation, and gas
condensates.
[0035] Methods of extracting mercaptan sulfur may include contacting the
hydrocarbon
stream with a caustic stream containing hydroxide and reacting at least a
portion of the mercaptan
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sulfur content of the hydrocarbon stream with the hydroxide in the caustic
stream. The hydroxide
may be any hydroxide capable of reacting with mercaptan sulfur. Some exemplary
hydroxides
may include Group I and Group II hydroxides such as NaOH, KOH, RbOH, Cs0H,
Ca(OH)2, and
Mg(OH)2, for example. The hydroxide may be present in an aqueous solution in a
concentration
suitable for a particular application, generally from about 5 wt.% up to and
including saturation.
[0036] The generalized reaction of hydroxide and mercaptan sulfur is shown in
Reaction
1 where the mercaptan sulfur (RSH) reacts with hydroxide (XOH), where X is a
Group I or Group
II cation, to form the corresponding mercaptide (RSX) and water.
RSH + XOH ¨> RSX + H20 Reaction 1
[0037] As discussed above, depending on the molecular weight of the mercaptan
sulfur
being reacted with the hydroxide, a portion of the mercaptide produced may
dissolve in the
aqueous portion of the caustic stream. Once the mercaptan sulfur is reacted
with the caustic stream,
a "spent caustic" or "rich caustic" solution containing the water, residual
hydroxide, and soluble
components may be generated. The spent caustic may be regenerated to form lean
caustic with
reduced mercaptide content for recycling back to Reaction 1. One process of
regeneration may
include mixing oxygen or air with the spent caustic and contacting the
resultant mixture with a
catalyst to regenerate the caustic stream. The generalized process of
regeneration is shown in
Reaction 2 where the mercaptide (RSX) reacts with water and oxygen in the
presence of a catalyst
produce disulfide (RSSR), also referred to as disulfide oil (DSO), caustic,
and water.
Catalyst
2RSX +2H20 + 2 02 _______________ > RSSR +2X0H + H20 Reaction 2
[0038] As discussed above, one of the challenges with treatment of mercaptan
sulfur is that
there may be issues with extent of reaction whereby the mercaptan sulfur
concentration is not
reduced to the level required for the resultant product stream to be on spec.
In units which utilize
an extractor section and an oxidation section, such as UOP Merox', the
catalyst may be dispersed
in the caustic stream which circulates through the extraction and oxidation
sections of the unit. In
sweetening units, the catalyst may be contained in a fixed bed within a
reactor. The catalyst may
be impregnated in charcoal or activated carbon where the catalyst bed may be
wetted with caustic
solution. In either case, the catalyst may not have enough catalytic activity
and/or residence time
within the reactor may be too short to effectively oxide the mercaptides. One
of the exemplary
uses of the catalytic carbon fibers disclosed herein is in replacing the
conventional oxygenation
catalysts presently utilized in the oxidation of mercaptides to produce
disulfide oil. As will be
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discussed in detail below, catalytic carbon fibers exhibit high reactivity to
oxidation of mercaptides
and have desirable physical properties which are well suited for use in
mercaptide oxidation
reactors.
[0039] There may be a wide variety of process conditions suitable for
oxidation of the
mercaptides, the exact conditions of which may vary depending on the
hydrocarbon feed. For
lighter hydrocarbons, operating pressure may be controlled to be slightly
above the bubble point
to ensure liquid-phase operation. For relatively heavier hydrocarbons,
pressure may be set to keep
air dissolved in the oxidation section. Operating temperature may also be
selected based on the
hydrocarbon feed with general conditions of temperature ranging from about 20
C to about 100
C.
[0040] FIG. 1 illustrates one embodiment of a hydrocarbon desulfurization
process 100
which may utilize catalytic carbon fibers in mercaptide oxidation. In FIG. 1,
hydrocarbon feed 102
containing mercaptan sulfur compounds may be treated in a counter current
multiple stage caustic
treatment section. Lean caustic 104 may be fed to a last stage 108 where the
lean caustic extracts
the mercaptans from the hydrocarbons entering last stage 108 after first being
treated in first stage
106. The caustic may be removed from last stage 108 as stream 110 and may be
fed to first stage
106 and be contacted with hydrocarbon feed 102. Spent caustic stream 112 may
be withdrawn
from first stage 106 and the treated hydrocarbon 114 may be withdrawn from
last stage 108. The
specific design of the caustic treatment section is not critical the
functionality of the catalytic
carbon fibers of the present disclosure, however, one design may include
staged contactors
operating in a counter-current configuration as schematically illustrated in
FIG. 1, and another
design may be using fiber film liquid-liquid contactor to assist in the mass
transfer of the
mercaptans from the hydrocarbon feed 102 into the caustic treatment solution.
[0041] Spent caustic 112 withdrawn from first stage 106 and oxidizer 118 may
be fed to
oxidation section 116. Oxidizer 118 may include any suitable oxidizer,
including air, oxygen,
hydrogen peroxide, or any other oxygen containing gas or compound which
releases oxygen.
Oxidation section 116 may include catalytic carbon fibers disclosed herein
capable of oxidizing
mercaptides present in spent caustic 112 to form disulfide oil. The
mercaptides, water, and oxygen
in spent caustic 112 may react according to Reaction 2 in the presence of the
catalytic carbon fibers
to produce disulfide oil, regenerated caustic, and water. The regenerated
caustic may be drawn off
as regenerated caustic stream 118 and the disulfide oil may be drawn off as
disulfide stream 124.
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Off-gas steam 126 containing residual gaseous hydrocarbons, air, oxygen, or
other gasses may be
withdrawn from oxidation section 116 and sent to a downstream unit for further
processing or to
flare as needed.
[0042] As the conditions within oxidation section 116 may be conducive to
forming an
explosive mixture with combinations of hydrocarbon and oxidizer, it may be
desired to operate
the oxidation section 116 such that the gasses present in oxidation section
116 are below the lower
explosive limit (LEL) or above the upper explosive limit (UEL). A gas stream
120 may optionally
be introduced into oxidation section 116 such that the LEL/UEL conditions are
maintained. Gas
stream 120 may include fuel gas, inert gas, or any other suitable gas to
control LEL/UEL. Another
alternative may be the inclusion of solvent stream 122 into oxidation section
116. Solvent stream
122 may be from any source but should preferably contain little to no
disulfide oil. Solvent stream
122 may be mixed with spent caustic stream 112 prior to entering the oxidation
section 116 or it
may be injected as a separate stream into the bottom of oxidation section 116.
The solvent may be
any light hydrocarbon or mixture of light hydrocarbons such as naphtha and
kerosene that will
assist in the separation of the disulfide oil from the caustic solution after
oxidation of the
mercaptans. The disulfide oil may have a higher solubility in the DSO as
compared to the aqueous
portion of spent caustic 112, with their differential of solubility providing
an extractive driving
force for the DSO. In examples where a solvent is utilized, the solvent may be
drawn off with the
disulfide oil in disulfide stream 124.
[0043] In some examples, regenerated caustic stream 118 may be further
purified in
solvent wash section 128 whereby a solvent stream 130 may contact regenerated
caustic stream
118 to further remove DSO from the regenerated caustic stream 118. A Spent
caustic stream 132
may be withdrawn from solvent wash section 128 and additional fresh caustic
from fresh caustic
stream 134 may be added to form lean caustic 104.
[0044] FIG. 2 illustrates one embodiment of a hydrocarbon desulfurization
vessel 200
containing catalytic carbon fibers described herein. As illustrated,
hydrocarbon desulfurization
vessel 200 contains a caustic treatment section 202 containing fiber bundle
204 and an oxidation
section 206 containing catalytic carbon fibers 208. Conduit 210 may contain
caustic treatment
section 202 containing fiber bundle 204 which may physically separate caustic
treatment section
202 from oxidation section 206 and provide a flow path for fluid to flow
through. Oxidation section
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206 containing catalytic carbon fibers 208 may be disposed in an annular space
formed between
conduit 210 and the walls of vessel 200.
[0045] The hydrocarbon feed 212 containing mercaptan sulfur compounds to be
treated
may be mixed with oxidizer 214 and introduced into conduit 210. In some
examples, sparger 218
may be utilized to distribute oxidizer 214 into hydrocarbon feed 21. Oxidizer
214 may include any
suitable oxidizer, including air, oxygen, hydrogen peroxide, or any other
oxygen containing gas or
compound which releases oxygen. Generally, the amount of oxidizer 214
introduced should be
sufficient to oxidize all mercaptan sulfur compounds present in hydrocarbon
feed 212. Once the
hydrocarbon/oxidizer feed is introduced into conduit 210, it may flow through
conduit 210 and
contact fiber bundle 204. Caustic stream 220 may be introduced into conduit
210 such that the
hydrocarbon/oxidizer feed may be mixed with caustic stream 220 before
contacting fiber bundle
204. In some examples, it may be desired to disperse the caustic from caustic
stream 220 to
enhance contact between the hydrocarbon phase from hydrocarbon feed 212 and
the aqueous phase
from caustic stream 220. In such examples, line 222 may be connected to a
distributor 224 disposed
above fiber bundle 204 whereby caustic stream 220 is connected to distributor
224 via line 222,
and the hydrocarbon/oxidizer feed may mix with the caustic from caustic stream
220 above fiber
bundle 204.
[0046] In either example, hydrocarbon/oxidizer feed and caustic from caustic
stream 220
may contact fiber bundle 204 which may cause the aqueous caustic to wet the
individual fibers of
fiber bundle 204. The aqueous caustic solution will form a film on fibers 204
which will be dragged
downstream through conduit 210 by passage of hydrocarbon through same conduit.
Both liquids
may be discharged into separation zone 226 of the vessel 200. The volume of
the hydrocarbon will
be greater because the aqueous caustic passes through the fiber bundle at a
lower volumetric flow
rate than the hydrocarbon. During the relative movement of the hydrocarbon
with respect to the
aqueous caustic film on the fibers, a new interfacial boundary between the
hydrocarbon and the
aqueous caustic solution is continuously being formed, and as a result fresh
aqueous caustic
solution is brought in contact with this surface and allowed to react with the
mercaptan sulfur or
other impurities such as phenolics, naphthenic acid and other organic acids in
the hydrocarbon.
Mercaptan sulfur present in the hydrocarbon feed may be reacted with the
caustic to produce
mercaptides as shown in Reaction 1.
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[0047] In separation zone 226, the aqueous caustic solution and hydrocarbon
may collect
in the lower portion of the vessel 200 and separate into hydrocarbon phase 228
and caustic phase
230. The interface 232 within vessel 200 may be kept at a level above the
bottom of the
downstream end of fiber bundle 204 so that the aqueous caustic film can be
collected directly in
the bottom of vessel 200 without it being dispersed into the hydrocarbon phase
228. Most of the
phenolate or naphthenate impurities which may cause plugging in a packed bed
are thus removed
from the hydrocarbon in the caustic phase. Not only does this increase
oxidation efficiency but
reduces maintenance costs as well. However, some impurities may remain in the
hydrocarbon
which may be necessary to further treat the with caustic solution in oxidation
section 206. Caustic
phase 230 may be withdrawn from vessel 200 via pump 234 and may be returned to
conduit 210
via caustic stream 220. The height of interface 232 within vessel 200 may be
controlled by level
controls system 236 which may include a level sensor, a level controller, and
a purge valve, which
may be configured to keep interface 232 at a level above the downstream end of
fiber bundle 204.
[0048] From separation zone 226, hydrocarbon phase 228 may flow upwards into
oxidation section 206, whereby the hydrocarbon phase 228 may contact catalytic
carbon fibers
208. Additional caustic, if necessary, may be introduced into oxidation
section 206 via line 238.
A distribution grid may be present in oxidation section 206 which may
distribute caustic from line
238 into oxidation section 206. In oxidation section 206 mercaptides, water,
and oxygen may react
according to Reaction 2 in the presence of the catalytic carbon fibers to
produce disulfide oil,
regenerated caustic, and water which may flow upwards through oxidation
section 206. The
additional caustic and hydrocarbon may be in contact and in concurrent flow
through oxidation
section 206. At the upper end of the catalytic carbon fibers, the additional
caustic may be separated
from the hydrocarbon by a liquid separator device such as chimney type trays
in separation section
240. While chimney type trays are illustrated, there may be many alternative
types of liquid
separators can be used such as overflow weirs, for example. The additional
hydroxide may be
collected in separation section 240 and be drawn off as stream 242 to be re-
introduced into
oxidation section 206. Makeup caustic 244 may be added intermittently and a
caustic purge may
be utilized as needed. Hydrocarbon product 246 may be withdrawn from the top
of separation
section 240. Off-gas buildup in vessel 200 may be drawn off through line 248
and be processed in
downstream units.
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[0049] FIG. 3 illustrates another embodiment of a hydrocarbon desulfurization
vessel 300
containing catalytic carbon fibers described herein. FIG. 3 illustrates a
process conducted in a
single vessel where a hydrocarbon feed 302, oxidizer 304, caustic stream 306,
and, optionally,
solvent stream 308 are introduced into oxidation section 310. Oxidizer 304 may
include any
suitable oxidizer, including air, oxygen, hydrogen peroxide, or any other
oxygen containing gas or
compound which releases oxygen. Each of the streams may be introduced into
vessel 300 through
distributor 312 which may distribute the fees into oxidation section 310.
Oxidation section 310
contains catalytic carbon fibers 314 arranged to receive the feeds from
distributor 312.
[0050] In oxidation section 310, the hydrocarbon from hydrocarbon feed 302 and
caustic
from caustic stream 306 may contact catalytic carbon fibers 314 which may
cause the aqueous
caustic to wet the individual fibers of catalytic carbon fibers 314. The
aqueous caustic solution
will form a film on catalytic carbon fibers 314 which will be dragged
downstream through
oxidation zone 310 by passage of hydrocarbon through vessel 300. During the
relative movement
of the hydrocarbon with respect to the aqueous caustic film on the fibers, a
new interfacial
boundary between the hydrocarbon and the aqueous caustic solution is
continuously being formed,
and as a result fresh aqueous caustic solution is brought in contact with this
surface and allowed
to react with the mercaptan sulfur or other impurities such as phenolics,
naphthenic acid and other
organic acids in the hydrocarbon. Mercaptan sulfur present in the hydrocarbon
feed may be reacted
with the caustic to produce mercaptides as shown in Reaction 1. The
mercaptides produced may
further react with oxygen provided by oxidizer 304 as shown in Rection 2 in
the presence of
catalytic carbon fibers 314 to produce disulfide oil, regenerated caustic, and
water.
[0051] The oxidation of mercaptides into disulfide oil occurring within the
oxidation
section 310 may results in a mixture composed of continuous phase caustic,
discontinuous phase
organic (disulfide oil, and solvent if present) droplets dispersed in the
caustic phase, and gas
(nitrogen and unreacted oxygen from air). The mixture of products, unreacted
reactants, and inert
species may exit oxidation section 310 and contact fiber bundle 318 and flow
into separation
section 316. The fiber bundle may promote phase separation as explained
previously. In separation
section 316, the aqueous caustic and hydrocarbon may collect in the lower
portion of separation
section 316 and separate into hydrocarbon phase 320, caustic phase 322, and
gas phase 324. Gas
from oxidizer 304 disengages from liquid stream at the outlet of fiber bundle
318 and exits through
a mist eliminator 326 as off-gas 328. The two immiscible liquids, as a single
stream, flow
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downwards along fiber bundle 318 during which organic hydrocarbon droplets
coalesce and form
hydrocarbon phase 320, while the aqueous caustic adheres to the fibers and
flows further
downward to form caustic phase 322.
[0052] Hydrocarbon phase 320 containing the hydrocarbons from hydrocarbon feed
302
as well as the generated disulfide oil and solvent, if present, may be
withdrawn as stream 330.
Caustic phase 322 may contain a residual amount of disulfide oil which may be
further reduced
before the caustic is recycled within vessel 300. Caustic phase 322 may be
withdrawn as stream
332 which may be mixed with fresh solvent stream 334 before contacting fiber
bundle 338 and
flowing into separation section 336. In separation section 336, the aqueous
caustic from caustic
phase 322 and solvent from solvent stream 334 may collect in the lower portion
of separation
section 336 and separate into solvent phase 340 and caustic phase 342. Solvent
phase 340 may
contain the bulk of any residual disulfide oil present in caustic phase 322
after flowing through
fiber bundle 338. Solvent phase 340 may be withdrawn and recycled to vessel
300 as solvent
stream 308. Caustic phase 342 may be withdrawn and recycled as stream 344.
[0053] FIG. 4 illustrates a standalone caustic regeneration unit 400
comprising catalytic
carbon fibers 402 disposed in oxidation zone 404. Spent caustic stream 406 may
be mixed with
oxidizer 408 and introduced into caustic regeneration unit 400 through
distributor 410. Spent
caustic stream may be from any unit, including those previously described
herein, which contains
a spent caustic and mercaptides. Oxidizer 408 may include any suitable
oxidizer, including air,
oxygen, hydrogen peroxide, or any other oxygen containing gas or compound
which releases
oxygen. The mixture of oxidizer 408 and spent caustic stream 406 may contact
catalytic carbon
fibers 402 which may cause the aqueous caustic to wet the individual fibers of
catalytic carbon
fibers 402. Mercaptides present in caustic stream 406 further react with
oxygen provided by
oxidizer 408 as shown in Rection 2 in the presence of catalytic carbon fibers
402 to produce
disulfide oil, regenerated caustic, and water which may flow upwards along
catalytic carbon fibers
402. The resultant disulfide oil, regenerated caustic, or both may be
withdrawn from regeneration
unit 400 as stream 412. Although illustrated in FIG. 4 as one stream, stream
412 may be two or
more streams such as in previous figures where an aqueous phase and oleaginous
phase are
separately withdrawn. Off-gas 414 may also be withdrawn from caustic
regeneration unit 400.
[0054] FIG. 5a illustrates a standalone caustic regeneration unit 500
comprising catalytic
fibers 502 disposed in an oxidation zone 504. Rich caustic stream 506,
containing mercaptides
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and/or sulfides enters the top of the vessel. Oxidizer 508 enters above the
distributor tray 510.
Oxidizer 508 may include any suitable oxidizer, including air, oxygen,
hydrogen peroxide, or any
other oxygen containing gas or compound which releases oxygen. An example of
the distributor
tray is shown in FIG. 5b but other variations may apply equally well. On the
distributor tray 510,
a solvent stream 520 may also be introduced above the distributor tray 510.
Distributor tray 510
distributes these phases onto the catalytic fiber 502. In some embodiments,
riser pipes 516 may be
disposed on distributor tray 510. The mixture of at least oxidizer 508 and
rich caustic stream 506
may contact the catalytic carbon fiber 502 which may cause the aqueous caustic
to wet the
individual fibers of catalytic carbon fibers 502. Mercaptides present in
caustic stream 506 further
react with oxygen provided by oxidizer 508 as shown in Rection 2 in the
presence of catalytic
carbon fibers 502 to produce disulfide oil, regenerated caustic, and water
which may flow
downwards along catalytic carbon fibers 502. The resultant disulfide oil,
regenerated caustic, or
both may be withdrawn from regeneration unit 500 as stream 512. Although
illustrated in FIG. 5
as one stream, stream 512 may be two or more streams such as in previous
figures where an
aqueous phase and oleaginous phase are separately withdrawn. Off-gas 514 may
also be withdrawn
from caustic regeneration unit 500. FIG. 5b shows a top view of distributor
tray 510 with riser
pipes 516 and holes 518 to allow for the fluids to flow through the
distributor tray 510.
[0055] Accordingly, the present disclosure may provide methods, systems, and
apparatus
that may relate to fluid-fluid contacting. The methods, systems. and apparatus
may include any of
the various features disclosed herein, including one or more of the following
statements.
[0056] Statement 1. A method of producing a catalytic carbon fiber comprising:
oxidizing
a virgin carbon fiber to produce an oxidized carbon fiber; reacting the
oxidized carbon fiber with
a polyamine compound to produce an amine modified carbon fiber; and reacting
the amine
modified carbon fiber with an organometallic macrocycle to produce the
catalytic carbon fiber.
[0057] Statement 2. The method of statement 1 wherein the step of oxidation
comprises
contacting the carbon fiber with an acid selected from hydrochloric acid,
nitric acid, phosphoric
acid, sulfuric acid, boric acid, hydrofluoric acid, hydrobromic acid,
perchloric acid, hydroiodic
acid, fl uoroanti m on i c acid, carborane acid, fluorobori c acid,
fluorosulfuri c acid, hydrogen
fluoride, triflic acid, perchloric acid, acetic acid, formic acid, citric
acid, oxalic acid, tartaric acid,
and combinations thereof.
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[0058] Statement 3. The method of statement 2 wherein the step of oxidation is
performed
at temperature in a range of about 0 C to about 150 C.
[0059] Statement 4. The method of any of statements 1-3 wherein the polyamine
compound comprises a primary or secondary polyamine with a carbon length from
C2-C20.
[0060] Statement 5. The method of any of statements 1-4 wherein the polyamine
compound comprises at least one polyamine compound selected from
ethylenediamine, propane-
1,3 -diamine, butane-1,4-diamine, pentane-1,
5-di ami ne, hexamethyl enedi amine,
diethylenetriamine, benzene-1,3,5-triamine, and combinations thereof.
[0061] Statement 6. The method of any of statements 1-5 wherein the step of
reacting the
oxidized carbon fiber with a polyamine compound is performed at a temperature
in a range of
about 0 C to 250 C.
[0062] Statement 7. The method of any of statements 1-6 wherein the step of
reacting the
amine modified carbon fiber with an organometallic macrocycle is performed at
a temperature in
a range of about 0 C to 150.
[0063] Statement 8. The method of any of statements 1-7 wherein the
organometallic
macrocycle comprises an unsubstituted metal phthalocyanine a substituted metal
phthalocyanine,
or combinations thereof
[0064] Statement 9. The method of statement 8 wherein the substituted metal
phthalocyanine is substituted with at least one of a halogen group, a hydroxyl
group, an amine
group, an alkyl group, an aryl group, a thiol group, an alkoxy group, a
nitrosyl group, or
combinations thereof.
[0065] Statement 10 The method of statement 8 wherein the unsubstituted metal
phthalocyanine or the substituted metal phthalocyanine comprises a metal
selected from vanadium
(V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc
(Zn), ruthenium (Ru),
rhodium (Rh), palladium (Pd), silver (Ag), and combinations thereof.
[0066] Statement 11. A method of producing a catalytic carbon fiber
comprising: oxidizing
a virgin carbon fiber to produce an oxidized carbon fiber; reacting an
organometallic macrocycle
with a polyamine compound to produce an amine modified organometallic
macrocycle; and
reacting the oxidized carbon fiber with an amine modified organometallic
macrocycle to produce
the catalytic carbon fiber.
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[0067] Statement 12. The method of statement 11 wherein the step of oxidation
comprises
contacting the carbon fiber with an acid selected from hydrochloric acid,
nitric acid, phosphoric
acid, sulfuric acid, boric acid, hydrofluoric acid, hydrobromic acid,
perchloric acid, hydroiodic
acid, fluoroantimonic acid, carborane acid, fluoroboric acid, fluorosulfuric
acid, hydrogen
fluoride, triflic acid, perchloric acid, acetic acid, formic acid, citric
acid, oxalic acid, tartaric acid,
and combinations thereof.
[0068] Statement 13. The method of any of statements 11-12 wherein polyamine
compound comprises at least one polyamine compound selected from
ethylenediamine, propane-
1,3 -di ami ne, butane-1,4-diamine, pentane-1,
5-di ami ne, hexamethyl enedi amine,
diethylenetriamine, benzene-1,3,5-triamine, and combinations thereof.
[0069] Statement 14. The method of any of statements 11-13 wherein the
organometallic
macrocycle comprises an unsubstituted metal phthalocyanine a substituted metal
phthalocyanine,
or combinations thereof.
[0070] Statement 15. The method of statement 14 wherein the substituted metal
phthalocyanine is substituted with at least one of a halogen group, a hydroxyl
group, an amine
group, an alkyl group, an aryl group, a thiol group, an alkoxy group, a
nitrosyl group, or
combinations thereof.
[0071] Statement 16. The method of statements 14-15 wherein the unsubstituted
metal
phthalocyanine or the substituted metal phthalocyanine comprises a metal
selected from vanadium
(V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc
(Zn), ruthenium (Ru),
rhodium (Rh), palladium (Pd), silver (Ag), and combinations thereof.
[0072] Statement 17. A catalytic carbon fiber comprising: a carbon fiber, an
amine
compound covalently bonded to the carbon fiber; and an organometallic
macrocycle covalently
bonded to the amine compound.
[0073] Statement 18. The catalytic carbon fiber of statement 17 wherein the
amine
compound comprises at least one polyamine compound selected from
ethylenediamine, propane-
1,3 -diamine, butane-1,4-diamine, pentane-
1,5-diamine, hexamethyl enedi amine,
di ethyl enetri amine, benzene-1,3,5-triamine, and combinations thereof.
[0074] Statement 19. The catalytic carbon fiber of any of statements 17-18
wherein the
amine compound comprises ethylenediamine.
23
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[0075] Statement 20. The catalytic carbon fiber of statement 19 wherein the
organometallic
macrocycle comprises a metal phthalocyanine.
[0076] Statement 21. A fiber bundle contactor comprising: a flow path defined
by a
conduit; a catalytic carbon fiber bundle disposed in the conduit; and an inlet
allowing fluid flow
into the flow path.
[0077] Statement 22. The fiber bundle contactor of statement 21 wherein the
catalytic
carbon fiber bundle comprises a carbon fiber, an amine compound covalently
bonded to the carbon
fiber, and an organometallic macrocycle covalently bonded to the amine
compound.
[0078] Statement 23. The fiber bundle contactor of any of statement claim 21-
22 wherein
the amine compound comprises a primary or secondary polyamine with a carbon
length from C2-
C20.
[0079] Statement 24. The fiber bundle contactor of any of statements 21-23
wherein the
amine compound comprises at least one polyamine compound selected from
ethylenediamine,
propane-1,3-di amine, butane-1,4-diamine, pentane-
1,5-di am i ne, hexamethyl en edi ami ne,
diethylenetriamine, benzene-1,3,5-triamine, and combinations thereof
[0080] Statement 25. The fiber bundle contactor of any of statements 21-24
wherein the
organometallic macrocycle comprises an unsubstituted phthalocyanine, a
substituted
phthalocyanine, or combinations thereof.
[0081] Statement 26. The fiber bundle contactor any of statements 21-25
wherein the
substituted metal phthalocyanine is substituted with at least one of a halogen
group, a hydroxyl
group, an amine group, an alkyl group, an aryl group, a thiol group, an alkoxy
group, a nitrosyl
group, or combinations thereof
[0082] Statement 27. The fiber bundle contactor of any of statements 21-26
wherein the
unsubstituted phthalocyanine or the substituted phthalocyanine comprises a
metal selected from
vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper
(Cu), zinc (Zn),
ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), and combinations
thereof.
[0083] Statement 28. The fiber bundle contactor any of statements 21-27
wherein the
catalytic carbon fiber bundle comprises a carbon fiber and ethylenediamine
covalently bonded to
the carbon fiber and phthalocyanine.
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[0084] Statement 29. The fiber bundle contactor of any of statements 21-28
wherein the
catalytic carbon fiber has a second order mercaptan oxidation rate constant of
at least 5.45*10^-4
(1/M*min) at 38 C.
[0085] Statement 30. A method comprising: introducing into vessel a
hydrocarbon
comprising mercaptan sulfur, an aqueous caustic solution, and an oxidizer;
reacting at least a
portion of the mercaptan sulfur and the aqueous caustic solution to produce a
mercaptide; and
reacting the mercaptide and the oxidizer in the presence of a catalytic carbon
fiber bundle to
produce a disulfide oil.
[0086] Statement 31. The method of statement 30 wherein the catalytic carbon
fiber bundle
comprises a carbon fiber, an amine compound covalently linked to the carbon
fiber, and an
organometallic macrocycle covalently linked to the amine compound.
[0087] Statement 32. The method of any of statements 30-31 wherein the amine
compound
comprises a primary or secondary polyamine with a carbon length from C2-C20.
[0088] Statement 33. The method of statements 30-32 wherein the amine compound
comprises at least one polyamine compound selected from ethylenediamine,
propane-1,3-diamine,
butane-1,4-diamine, pentane-1,5-di amine, hexam ethyl enedi amine, di ethyl
enetriamine, benzene-
1,3,5-triamine, and combinations thereof.
[0089] Statement 34. The method of statements 30-33 wherein the organometallic
macrocycle comprises an unsubstituted phthalocyanine a substituted
phthalocyanine, or
combinations thereof.
[0090] Statement 35. The method of statements 30-34 wherein the substituted
metal
phthalocyanine is substituted with at least one of a halogen group, a hydroxyl
group, an amine
group, an alkyl group, an aryl group, a thiol group, an alkoxy group, a
nitrosyl group, or
combinations thereof.
[0091] Statement 36. The method of statements 30-35 wherein the unsubstituted
phthalocyanine or the substituted phthalocyanine comprises a metal selected
from vanadium (V),
manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn),
ruthenium (Ru),
rhodium (Rh), palladium (Pd), silver (Ag), and combinations thereof.
[0092] Statement 37. The method of statements 30-36 further comprising
contacting the
hydrocarbon comprising mercaptan sulfur and the aqueous caustic solution on a
fiber bundle,
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wherein the reacting the portion of the mercaptan sulfur and the aqueous
caustic solution to
produce a mercaptide occurs within the fiber bundle.
[0093] Statement 38. The method of statements 30-37 wherein the reacting the
mercaptide
and the oxidizer in the presence of the catalytic carbon fiber bundle further
produces a regenerated
caustic stream and wherein the regenerated caustic stream is recycled to the
vessel.
[0094] Statement 39. A method comprising: introducing into vessel an aqueous
solution
comprising a mercaptide and an oxidizer; and reacting the mercaptide and the
oxidizer in the
presence of a catalytic carbon fiber bundle to produce an aqueous caustic
solution.
[0095] Statement 40. The method of statement 40 wherein the catalytic carbon
fiber bundle
comprises a carbon fiber, a primary or secondary polyamine with a carbon
length from C2-C20
covalently linked to the carbon fiber, and an unsubstituted phthalocyanine or
substituted
phthalocyanine covalently linked to the amine compound.
[0096] Statement 41. A method of producing a catalytic carbon fiber
comprising:
providing a carbon fiber and an aminated macrocycle, mixing the carbon fiber
and the aminated
macrocycle with a solvent; and reacting the carbon fiber and the aminated
macrocycle to form an
amide bond between the carbon fiber and the aminated macrocycle thereby
forming the catalytic
carbon fiber,
[0097] Statement 42. The method of statement 41, wherein the aminated
macrocycle
comprises an organometallic macrocycle and an amine group grafted to the
organometallic
macrocycle.
[0098] Statement 43. The method of statement 42, wherein the organometallic
macrocycle
comprises an unsubstituted metal phthalocyanine a substituted metal
phthalocyanine, or
combinations thereof.
[0099] Statement 44. The method of statement 43 wherein the substituted metal
phthalocyanine is substituted with at least one of a halogen group, a hydroxyl
group, an alkyl
group, an aryl group, a thiol group, an alkoxy group, a nitrosyl group,
sulfonic group, or
combinations thereof.
[0100] Statement 45, The method of statements 43-44, wherein the unsubstituted
metal
phthalocyanine or the substituted metal phthalocyanine comprises a metal
selected from vanadium
(V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc
(Zn), ruthenium (Ru),
rhodium (Rh), palladium (Pd), silver (Ag), and combinations thereof.
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[0101] Statement 46. The method of claim 42, wherein the amine group comprises
an
amine with a carbon length from C2-C20.
[0102] Statement 47. The method of any of statements 41-46, wherein the
solvent comprise
at least one solvent selected from the group consisting of water, pyridine,
DMSO, DMF, THF,
ethanol, acetonitrile, chloroform, ethylene glycol, methanol, benzene, and
combinations thereof.
[0103] Statement 48. The method of statement 42, wherein the amine group
comprises a
reaction product of at least one amine compound selected from ethylenediamine,
propane-1,3-
diamine, butane-1,4-diamine, pentane-1,5-diamine, hexamethylenediamine,
diethylenetriamine,
benzene-1,3,5-triamine, and combinations thereof.
[0104] Statement 49. The method of any of statements 41-48, wherein the
aminated
macrocycle comprises at least one of mono-amino cobalt phthalocyanine, di-
amino cobalt
phthalocyanine, tri-amino cobalt phthalocyanine, tetra-amino cobalt
phthalocyanine, and
combinations thereof.
[0105] Statement 50. The method of any of statements 41-49, wherein the
reacting is
carried out at a temperature in a range of about 100 C to about 200 C.
[0106] Statement 51. A method of producing a catalytic carbon fiber
comprising:
providing a carbon fiber; reacting the carbon fiber with a chlorinating agent
to produce a carbon
fiber comprising acyl chloride; and reacting the carbon fiber comprising acyl
chloride with an
aminated macrocycle to form an amide bond between the carbon fiber comprising
acyl chloride
and the aminated macrocycle thereby forming the catalytic carbon fiber.
[0107] Statement 52. The method of statement 51, wherein the chlorinating
agent
comprises a chlorinating agent selected from the group consisting of thionyl
chloride, phosphorous
trichloride, terephthaloyl chloride and combinations thereof
[0108] Statement 53. The method of any statements 51-52, wherein the aminated
macrocycle comprises an organometallic macrocycle and an amine group grafted
to the
organometallic macrocycle.
[0109] Statement 54. The method of statement 53, wherein the organometallic
macrocycle
comprises an unsubstituted metal phthalocyanine a substituted metal
phthalocyanine, or
combinations thereof.
[0110] Statement 55. The method of statements 53-54 wherein the substituted
metal
phthalocyanine is substituted with at least one of a halogen group, a hydroxyl
group, an alkyl
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group, an aryl group, a thiol group, an alkoxy group, a nitrosyl group,
sulfonic group, or
combinations thereof.
[0111] Statement 56. The method of statements 53-55, wherein the unsubstituted
metal
phthalocyanine or the substituted metal phthalocyanine comprises a metal
selected from vanadium
(V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc
(Zn), ruthenium (Ru),
rhodium (Rh), palladium (Pd), silver (Ag), and combinations thereof.
[0112] Statement 57. The method of any of statements 51-56, further comprising
removing
the thionyl chloride from the carbon fiber comprising acyl chloride and
dispersing the carbon fiber
comprising acyl chloride in a solvent prior to the step of reacting the carbon
fiber comprising acyl
chloride with an aminated macrocycle.
[0113] Statement 58. The methods of any of statements 51-57, wherein the step
of reacting
the carbon fiber comprising acyl chloride with an aminated macrocycle
comprises reacting in the
presence of pyridine.
[0114] Statement 59. A method of producing a catalytic carbon fiber
comprising:
providing a carbon fiber; reacting the carbon fiber with a coupling agent to
produce a
functionalized carbon fiber; and reacting the functionalized carbon fiber with
an aminated
macrocycle to form an amide bond between the carbon fiber and the aminated
macrocycle thereby
forming the catalytic carbon fiber.
[0115] Statement 60 The method of statement 59, wherein the coupling agent
comprises
carbodiimide, benzotriazole, or combinations thereof.
[0116] Statement 61. A method of producing a catalytic carbon fiber
comprising:
providing a carbon fiber; providing an enzyme capable of catalyzing an amide
bond formation;
and reacting the carbon fiber with an aminated macrocycle in the presence of
the enzyme to form
a bond between the carbon fiber and the aminated macrocycle thereby forming
the catalytic carbon
fiber.
[0117] Statement 62. The method of statement 61 wherein the enzyme comprises
an
enzyme selected from the group consisting of proteases, subtilisin, acylases,
amidases lipases, and
combinations thereof.
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EXAMPLES
[0118] To facilitate a better understanding of the present disclosure, the
following
illustrative examples of some of the embodiments are given. In no way should
such examples be
read to limit, or to define, the scope of the disclosure.
EXAMPLE 1
[0119] In this example, mercaptan oxidation potential of virgin carbon fibers
were
evaluated. Kerosene containing 300 ppm of mercaptan sulfur was prepared. A 3
gram sample of
virgin carbon fiber and 150 mL of the mercaptan sulfur containing kerosene was
mixed vigorously
in a shaker bath at 300 RPM and 38 C. Kerosene samples were withdrawn over
the course of 30
minutes and the mercaptan concentration in each sample was determined by
titration. The second
order mercaptan oxidation rate constant was calculated to be 0.22*10-4
(1NI*min). It was observed
that the virgin carbon fiber showed little catalytic activity toward mercaptan
oxidation.
EXAMPLE 2
[0120] In this example, cobalt phthalocyanine modified carbon fiber was
prepared and the
mercaptan oxidation of the modified carbon fiber was evaluated. A dimethyl
sulfoxide (DMSO)
solution was prepared by mixing 4 g of 4-aminopyridine with 200 mL of DMSO.
Thereafter, 4
grams of virgin carbon fiber was measured and added to the DMSO solution and
the mixture was
maintained at 80 C for 22 hours. The carbon fiber was washed with iso-propyl
alcohol followed
by washing with distilled water and drying at 60 C in air. After drying, the
carbon fibers were
mixed in an aqueous solution containing 1% di-brominated cobalt phthalocyanine
at room
temperature for 15 hours. Thereafter, the cobalt phthalocyanine modified
carbon fiber was washed
with distilled water and dried at 60 C.
[0121] Kerosene containing 300 ppm of mercaptan sulfur was prepared. A 3 gram
sample
of cobalt phthalocyanine modified carbon fiber from this example and 150 mL of
the mercaptan
sulfur containing kerosene was mixed vigorously in a shaker bath at 300 RPM
and 38 C. Kerosene
samples were withdrawn over the course of 30 minutes and the mercaptan
concentration in each
sample was determined by titration. The second order mercaptan oxidation rate
constant was
calculated to be 3.5*104 (1/M*min).
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EXAMPLE 3
[0122] In this example, cobalt phthalocyanine modified carbon fiber was
prepared by the
methods described above and the mercaptan oxidation of the modified carbon
fiber was evaluated.
g of virgin carbon fiber was measured and added to 175 mL of 70% nitric acid
at 80 C for 5
hours. After nitric treatment, the carbon fibers were washed with distilled
water and thereafter
mixed with ethylenediamine at 105 C for 3 hours to obtain amine modified
carbon fiber.
Thereafter, the amine modified carbon fiber was added to a pyridine solution
containing 1.3 wt.%
di-brominated cobalt phthalocyanine at room temperature for 22 hours.
[0123] Kerosene containing 300 ppm of mercaptan sulfur was prepared. A 3 gram
sample
of the cobalt phthalocyanine modified carbon fiber from this example and 150
mL of the mercaptan
sulfur containing kerosene was mixed vigorously in a shaker bath at 300 RPM
and 38 C. Kerosene
samples were withdrawn over the course of 30 minutes and the mercaptan
concentration in each
sample was determined by titration. The second order mercaptan oxidation rate
constant was
calculated to be 5.45*10-4 (1/M*min). It was observed that the mercaptan
oxidation activity was
increased by 56% using the amine method for preparing cobalt phthalocyanine
modified carbon
fiber.
[0124] Therefore, the present disclosure is well adapted to attain the ends
and advantages
mentioned as well as those that are inherent therein. The particular
embodiments disclosed above
are illustrative only, as the present disclosure may be modified and practiced
in different but
equivalent manners apparent to those skilled in the art having the benefit of
the teachings herein.
Although individual embodiments are discussed, the disclosure covers all
combinations of all those
embodiments. Furthermore, no limitations are intended to the details of
construction or design
herein shown, other than as described in the claims below. Also, the terms in
the claims have their
plain, ordinary meaning unless otherwise explicitly and clearly defined by the
patentee. It is
therefore evident that the particular illustrative embodiments disclosed above
may be altered or
modified and all such variations are considered within the scope and spirit of
the present disclosure.
If there is any conflict in the usages of a word or term in this specification
and one or more patent(s)
or other documents that may be incorporated herein by reference, the
definitions that are consistent
with this specification should be adopted.
Date Recue/Date Received 2023-06-14
