U.S. patent application number 13/978657 was filed with the patent office on 2013-10-31 for low cost immobilized amine regenerable solid sorbents.
This patent application is currently assigned to THE UNIVERSITY OF AKRON. The applicant listed for this patent is Steven S. C. Chuang. Invention is credited to Steven S. C. Chuang.
Application Number | 20130287662 13/978657 |
Document ID | / |
Family ID | 43618326 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130287662 |
Kind Code |
A1 |
Chuang; Steven S. C. |
October 31, 2013 |
Low Cost Immobilized Amine Regenerable Solid Sorbents
Abstract
A method of modifying a chemical interaction between a
functional group of an immobilized amine in a solid sorbent
composition and a compound that chemically interacts with the
functional group to reduce the heat required to desorb the compound
from the solid sorbent. A method of inhibiting degradation of an
immobilized amine in an immobilized amine solid sorbent.
Compositions and methods of use of a low-cost regenerable
immobilized amine solid sorbent resistant to degradation.
Inventors: |
Chuang; Steven S. C.;
(Hudson, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chuang; Steven S. C. |
Hudson |
OH |
US |
|
|
Assignee: |
THE UNIVERSITY OF AKRON
Akron
OH
|
Family ID: |
43618326 |
Appl. No.: |
13/978657 |
Filed: |
January 7, 2011 |
PCT Filed: |
January 7, 2011 |
PCT NO: |
PCT/US10/54277 |
371 Date: |
July 11, 2013 |
Current U.S.
Class: |
423/228 ;
252/184; 423/210; 423/242.7; 427/207.1 |
Current CPC
Class: |
B01D 53/02 20130101;
B01D 53/62 20130101; B01J 20/22 20130101; B01J 20/3425 20130101;
B01J 20/3242 20130101; B01J 20/3251 20130101; B01D 2252/204
20130101; B01D 2257/504 20130101; B01J 20/043 20130101; B01J
20/3223 20130101; B01J 20/3483 20130101; B01D 2257/404 20130101;
B01D 2253/106 20130101; B01D 2257/306 20130101; B01D 53/81
20130101; Y02C 10/08 20130101; B01D 2257/302 20130101; B01J 20/3289
20130101; B01D 2253/25 20130101; B01J 20/3204 20130101; B01J 20/103
20130101; Y02C 20/40 20200801; B01J 20/3219 20130101; B01D 53/508
20130101; B01D 2257/304 20130101 |
Class at
Publication: |
423/228 ;
423/210; 252/184; 423/242.7; 427/207.1 |
International
Class: |
B01J 20/32 20060101
B01J020/32; B01D 53/62 20060101 B01D053/62; B01D 53/50 20060101
B01D053/50; B01J 20/22 20060101 B01J020/22 |
Claims
1. A method of modifying a chemical interaction between i) an amine
functional group of an immobilized amine in a solid sorbent
composition, and, ii) a gaseous compound that chemically interacts
with the amine functional group, by causing the adsorption of the
gaseous compound on the immobilized amines in the presence of an
alcohol species.
2. The method of claim 1 wherein the immobilized amine is prepared
from an aliphatic or aromatic amine and an epoxy on a solid
support, said solid support comprising an oxide, a metal, a carbon
material, or a combination thereof.
3. The method of claim 1 wherein the chemically adsorbed compound
is an acidic gas, said acidic gas comprising, sulfur dioxide,
hydrogen sulfide, carbonyl sulfide, CS2, thiopene,
dibenzothiophene, tetrahydrothiophene, dimethyl sulfide, mercaptan,
tertbutylmercaptant, 2-methyl-2propanethiol, 1-propanethiol,
isobutanethiol, 2-butanethiol, I-butanethiol, 1-pentanethiol,
I-hexanethiol, and I-heptanethiol, nitric oxide, nitrogen oxide,
carbon dioxide, or some combination thereof.
4. The method of claim 1 wherein the alcohol species is a
glycol.
5. A method comprising: a. inhibiting degradation of amine
functional groups of an immobilized amine in a solid sorbent
composition b. by including an inorganic base in the solid sorbent
composition.
6. A regenerable immobilized amine solid sorbent composition
comprising: a. a solid support particle, b. an immobilized amine,
i. wherein the immobilized amine comprises an adhesive and an amine
susceptible to adsorbing a compound, c. an alcohol species capable
of lowering the threshold temperature for dissociation of a bond
between the compound and the immobilized amine, and; d. an
inorganic base.
7. The composition of claim 6 wherein the solid support particle is
SiO.sub.2.
8. The composition of claim 6 wherein the amine is an aliphatic or
aromatic amine.
9. The composition of claim 6 wherein the adhesive is an epoxy.
10. The composition of claim 6 wherein the alcohol species is a
polyethylene glycol.
11. The composition of claim 6 wherein the inorganic base is
Na.sub.2CO.sub.3.
12. A method of removing a compound from a gas stream comprising:
a. employing a regenerable solid sorbent in the gas stream, wherein
the regenerable solid sorbent comprises, i. an immobilized amine
susceptible to chemosorbing the compound, ii. an alcohol species
capable of lowering the threshold temperature for dissociation of
the bond between the compound and the amine, and iii. an inorganic
base, b. allowing the regenerable solid sorbent to adsorb the
compound from the gas stream, and; c. heating the solid sorbent to
a temperature above the threshold temperature for dissociation of
the bond between the adsorbed compound and the immobilized amine,
but below the threshold temperature for dissociation of the
immobilized amine.
13. The method of claim 12 wherein the gas stream is flue gas, the
compound is CO.sub.2, the solid support is SiO.sub.2, the amine is
an aliphatic amine, the adhesive is an epoxy, the alcohol species
is a polyethylene glycol and the inorganic base is
Na.sub.2CO.sub.3.
14. The method of claim 12 wherein the gas stream is flue gas and
the compound is SO.sub.2, the solid support is SiO.sub.2, the amine
is an aromatic amine, the adhesive is an epoxy, the alcohol species
is a polyethylene glycol and the inorganic base is
Na.sub.2CO.sub.3.
15. A method of preparing a dual immobilized amine regenerable
solid sorbent for adsorbing a first compound and a second compound,
comprising: a. impregnating into pores of a solid support a first
composition comprising, i. a first amine susceptible to
chemosorbing the first compound, ii. an adhesive, iii. an alcohol
species capable of lowering the threshold temperature for
dissociation of the bond between the first compound and the first
amine, and iv. an inorganic base, b. optionally partially filling
the pores with a solvent after impregnating the pores with the
first composition, c. treating the resultant solid support with a
second composition comprising, i. a second amine susceptible to
chemosorbing the second compound, ii. an adhesive, iii. an alcohol
species capable of lowering the threshold temperature for
dissociation of the bond between the second compound and the second
amine, and, iv. an inorganic base, and; d. optionally, removing the
solvent from the pores.
16. The method of claim 15 wherein the first compound is CO.sub.2
and the first composition comprises an aliphatic amine, a
polyethylene glycol, an epoxy and Na.sub.2CO.sub.3, and the second
compound is SO.sub.2 and the second composition comprises an
aromatic amine, a polyethylene glycol, an epoxy and
Na.sub.2CO.sub.3.
17. The method of claim 16 wherein the solvent is water.
18. A dual immobilized amine regenerable solid sorbent composition,
comprising: a. solid support particles having pores, pore mouths
and a non-porous surface area, b. wherein the pores contain a
composition of a first amine susceptible to chemosorbing a first
compound, an alcohol species capable of lowering the threshold
temperature for dissociation of a bond between the first compound
and the first amine, an adhesive, and an inorganic base, and; c.
wherein the pore mouths and non-porous surface area contain a
composition of a second amine susceptible to chemosorbing a second
compound, an alcohol species capable of lowering the threshold
temperature for dissociation of a bond between the second compound
and the second amine, an adhesive, and an inorganic base.
19. The composition of claim 18 wherein the solid support particles
are SiO.sub.2 particles, the first compound is CO.sub.2, the amine
susceptible to chemosorbing a first compound is an aliphatic amine,
the alcohol species is a polyethylene glycol, the adhesive is an
epoxy and the inorganic base is Na.sub.2CO.sub.3.
20. The composition of claim 18 wherein the solid support particles
are SiO.sub.2 particles, the second compound is SO.sub.2, the amine
susceptible to chemosorbing a second compound is an aromatic amine,
the alcohol species is a polyethylene glycol, the adhesive is an
epoxy and the inorganic base is Na.sub.2CO.sub.3.
Description
[0001] This application claims priority from U.S. Provisional
Patent Application Ser. No. 61/255,173 filed on Oct. 27, 2009 and
from U.S. Provisional Patent Application Ser. No. 61/255,178 filed
on Oct. 27, 2009, both of which are incorporated by reference
herein.
BACKGROUND
[0002] The subject matter relates to methods for preparing low-cost
regenerable immobilized amine solid sorbents, and compositions and
methods for using the same to regenerably remove compounds such as
CO.sub.2, SO.sub.2, or other acidic gases from a gas stream.
[0003] Sulfur dioxide (SO.sub.2) in the flue gas of a coal-fired
power plant is primarily removed by a wet scrubber method that
involves use of large equipment requiring large amounts of energy
and the generation of corrosive sulfate by-products. The fixed and
operation costs of SO.sub.2 removal due to the foregoing factors
can be significantly decreased by using a solid sorbent
process.
[0004] It has been shown that SO.sub.2 can be strongly bound on the
functional groups of an amine molecule that is immobilized on a
solid surface. (Khatri, Rajesh A., et al. Thermal and Chemical
Stability of Regenerable Solid Amine Sorbent for CO.sub.2 Capture.
Energy & Fuels (2006), 20(4), 1514-1520). However, due to this
strong binding, SO.sub.2 is not readily desorbed from the
immobilized amine. Attempts to desorb SO.sub.2 species at
temperatures above 180.degree. C. have caused the decomposition of
the immobilized amines.
[0005] To improve the thermal stability of amines on solid
sorbents, as well as eliminate degradation problems in the process
of removing CO.sub.2, SO.sub.2, or other acidic gases from a gas
stream, and reduce the overall cost of the CO.sub.2, SO.sub.2, or
other acidic gases removal process, it has been found that the high
temperature decomposition of an immobilized amine on a solid
support can be inhibited by the presence of an alcohol species,
such as glycol, in the process of producing the sorbent.
SUMMARY
[0006] Provided is a method of modifying a chemical interaction
between a functional group of an immobilized amine in a solid
sorbent composition and a compound that chemically interacts with
the functional group. Modifying the chemical interaction reduces
the heat required to desorb the compound from the functional group
compared to an unmodified chemical interaction between the
functional group and the compound. Modification may be done by
causing the chemical interaction between the functional group and
the compound to take place in the presence of an alcohol
species.
[0007] Further provided is a method comprising inhibiting
degradation of a functional group of an immobilized amine in a
solid sorbent composition. Inhibition may be accomplished by
including an inorganic base in the solid sorbent composition.
[0008] Further provided is a regenerable immobilized amine solid
sorbent composition. The composition may comprise a solid support
particle and an immobilized amine. The immobilized amine may
comprise an adhesive and an amine susceptible to adsorbing a
compound. The sorbent composition may additionally comprise an
alcohol species capable of lowering the threshold temperature for
dissociation of a bond between the compound and the immobilized
amine, and an inorganic base.
[0009] Further provided is a method of removing a compound from a
gas stream. The method may comprise employing a regenerable solid
sorbent in the gas stream. The regenerable solid sorbent may
comprise an immobilized amine susceptible to chemosorbing the
compound, an alcohol species capable of lowering the threshold
temperature for dissociation of the bond between the compound and
the amine, and an inorganic base. The method may further comprise
allowing the regenerable solid sorbent to adsorb the compound from
the gas stream, and heating the solid sorbent to a temperature
above the threshold temperature for dissociation of the bond
between the adsorbed compound and the immobilized amine, but below
the threshold temperature for dissociation of the immobilized
amine.
[0010] Further provided is a dual immobilized amine regenerable
solid sorbent composition. The composition comprises solid support
particles having pores, pore mouths and a non-porous surface area.
The pores may comprise a composition of a first amine susceptible
to chemosorbing a first compound, an alcohol species capable of
lowering the threshold temperature for dissociation of a bond
between the first compound and the first amine, an adhesive, and an
inorganic base. The pore mouths and non-porous surface area may
comprise a composition of a second amine susceptible to
chemosorbing a second compound, an alcohol species capable of
lowering the threshold temperature for dissociation of a bond
between the second compound and the second amine, an adhesive, and
an inorganic base.
[0011] Further provided, is a method of preparing a dual
immobilized amine regenerable solid sorbent for adsorbing a first
compound and a second compound. The method may comprise
impregnating into pores of a solid support a first composition. The
first composition may comprise a first amine susceptible to
chemosorbing the first compound, an adhesive, an alcohol species
capable of lowering the temperature for the dissociation of the
bond between the first compound and the first amine, and an
inorganic base. The pores may optionally be partially filled with a
solvent after impregnating the pores with the first composition.
The method may further comprise treating the resultant solid
support with a second composition. The second composition may
comprise a second amine susceptible to chemosorbing the second
compound, an adhesive, an alcohol species capable of lowering the
threshold temperature for dissociation of the bond between the
second compound and the second amine, and an inorganic base. The
method may further comprise, optionally, removing the solvent from
the pores.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] By way of example only, certain non-limiting embodiments are
described more fully hereinafter with reference tables and to the
accompanying figures, wherein:
[0013] FIG. 1 is an explanatory graph of the SO.sub.2 Capture
Capacity of a TPS regenerable solid sorbent;
[0014] FIG. 2 is an explanatory graph of the CO.sub.2 Capture
Profiles of a TPS regenerable solid sorbent;
[0015] FIG. 3 is an explanatory graph of the CO.sub.2 Capture
Capacity of a PhPS regenerable solid sorbent;
[0016] FIG. 4 is an explanatory graph of the SO.sub.2 Capture
Profiles of a PhPS regenerable solid sorbent;
[0017] FIG. 5 is an explanatory graph of the H.sub.2S Capture
Profiles of a PhPS regenerable solid sorbent;
[0018] FIG. 6 is an explanatory graph of the NO Capture Profiles of
a PhPS regenerable solid sorbent.
DETAILED DESCRIPTION
[0019] Provided is a method of modifying the chemical interaction
of a compound with an immobilized amine to reduce the temperature
at which the compound can be desorbed from the immobilized amine.
The temperature at which the compound can be desorbed from the
immobilized amine can be referred to as the desorption threshold
temperature. The desorption threshold temperature can be lowered to
a temperature below the temperature at which the immobilized amine
would otherwise begin to decompose, or the immobilized amine
decomposition threshold temperature. This method may not only can
lower the cost of the desorption process by lowering the energy
needs for desorption, but may also make it possible to desorb
compounds that have heretofore not been desorbable.
[0020] Also provided is a method of reducing degradation of
immobilized amine solid sorbents and a method and composition for
removing a desired compound from a gas stream while resisting
compounds in the gas stream that would otherwise block removal of
the desired compound or cause degradation.
[0021] The foregoing methods make possible the production of a
low-cost regenerable immobilized amine solid sorbent resistant to
degradation. The sorbent composition comprises a solid support
containing thereon an immobilized amine. The sorbent can be
considered regenerable when it can be exposed to many cycles of
adsorbing and desorbing a compound with little or no decomposition
of the sorbent. Many cycles can be, for example, and without
limitation more than 350 cycles, more than 400 cycles, more than
450 cycles, or more than 500 cycles. In addition, the sorbent
composition can be prepared in a manner that inhibits degradation
of the immobilized amine and its adsorbent ability. Cost of
producing the sorbent, the materials used in the sorbent, and the
energy required to desorb compounds from the sorbent can be reduced
or minimized.
[0022] An immobilized amine is a complex in which individual
neighboring molecules of the amine have become stationary, or
immobilized, relative to one another and possibly a fixed object,
such as a solid support particle or a large molecule. In one
method, an amine becomes an immobilized amine due to the linking of
a fraction of the amine functional groups on individual neighboring
amine molecules. Given the proclivity of amines to form bonds with
organic compounds, an organic adhesive can be mixed with an amine
to bind with a fraction of the amine functional groups on
individual amine molecules to cause the linking of the amine
functional groups. As the adhesive cures, generally at a
temperature of between about 20.degree. C. and 160.degree. C., it
links neighboring amine molecules together forming an immobilized
amine. Prior to curing, the amine/adhesive mixture can then be
impregnated on a solid support so that curing of the adhesive will
immobilize the amine with respect to the solid support as well. The
adhesive is selected based on considerations such as thermal and
chemical stability in the immobilized amine, but any chemical
compound containing a functional group that reacts chemically with
the amine may be an adhesive candidate. In certain embodiments, the
adhesive may be an epoxy, such as, for example and without
limitation, a bisphenol epoxy, diglycidyl ether of bisphenol A
(DGEBA), EPON-828, or mixtures thereof. The In certain embodiments,
the adhesive may be selected from other polymers such as a compound
containing isocynate, such as 2,4-tolylene diisocyanate dimer.
[0023] The foregoing method can work with any degree of amine,
including but not limited to primary and secondary amines. Although
secondary amines generally exhibit a better attraction for chemical
absorbency, secondary amines can be expensive. Due to the high cost
of secondary amines, the method of immobilizing amines for use in
solid sorbents can be useful in lowering the cost of immobilized
amine sorbents by allowing use of lower cost primary amines. In
particular, the process of bonding an adhesive to a primary group
transforms the primary group into a secondary amine functional
group. Thus, immobilization can not only prevent an amine from
corroding away, but also can be an effective method for lowering
the cost of a solid sorbent without sacrificing performance.
[0024] In addition, the amines that can be used comprise aliphatic
amines, aromatic amines, or mixtures thereof. While the functional
groups on both aliphatic and aromatic amines can attract and adsorb
a wide variety of compounds, both have properties that can be
utilized for particular purposes. For example, aliphatic amines
exhibit the properties of a strong base and can be used to adsorbed
compounds that exhibit properties of a weak acid, such as, for
example, CO.sub.2. Similarly, aromatic amines exhibit the
properties of a weak base, and can be used to adsorbed compounds
that exhibit the properties of a strong acid, such as sulfur
compounds, for example SO.sub.2.
[0025] Unfortunately, certain compounds form bonds when they
chemically adsorb with an immobilized amine that are stronger than
the bonds between the adhesive and the amine in the immobilized
amine. For such compounds, regeneration of the sorbent by
desorption of the compound has not been possible. One example of
such a compound, as mentioned above, is SO.sub.2. The bonds of an
SO.sub.2 chemically adsorbed on an immobilized amine have been
heated to temperatures of greater than 180.degree. C. without
desorbing. At this temperature, the immobilized amine
decomposes.
[0026] Provided is a method of lowering the desorption threshold
temperature of compounds that chemically adsorb on an immobilized
amine sorbent, by causing the compounds to adsorb on the
immobilized amine in the presence of an alcohol species. Typical
operating temperatures at which compounds can be adsorbed can be
between 20.degree. C. and 80.degree. C. It has been found that an
alcohol species can modify the chemical interaction of compounds
with the functional groups of the immobilized amine. The
modification causes the adsorbed compounds to desorb at a lower
temperature compared to when the reaction is not modified. Chemical
adsorption can be caused to occur in the presence of an alcohol
species, for example, by including the alcohol species in the
immobilized amine composition. If the alcohol species is present
during the curing stage in the process of preparing the immobilized
amine, the alcohol species is present during the chemical
interaction. The sorbent also can be suspended in the alcohol
species and then introduced to a stream containing the compound to
be adsorbed. Another alternative can be to inject an alcohol
species mist into a gas stream containing the compound to be
adsorbed so that both compound and alcohol species are carried to
the adsorption site. The amount of the alcohol species present in
the composition can be determined by infra-red spectroscopy. The
alcohol species in the composition can be any compound comprising a
C-OH group including, but not limited to, alcohols, diols and
triols. Some non-limiting examples of alcohols include polyethylene
glycol, polyvinyl alcohol, or mixtures thereof.
[0027] Also provided is a method of inhibiting degradation of the
functional groups of the immobilized amine. In certain gas streams,
such as, for example, flue gas, acidic gases can be present. A gas
stream may comprise acidic gases such as sulfur compounds, such as
sulfur dioxide (SO.sub.2), hydrogen sulfide (H.sub.2S), carbonyl
sulfide (COS), CS.sub.2, thiopene, dibenzothiophene,
tetrahydrothiophene (THT), dimethyl sulfide (DMS), mercaptan,
tertbutylmercaptant (TBM), 2-methyl-2propanethiol, 1-propanethiol,
isobutanethiol, 2-butanethiol, 1-butanethiol, 1-pentanethiol,
1-hexanethiol, and 1-heptanethiol. A gas stream may comprise acidic
gases such as, nitrogen compounds, such as nitric oxide and
nitrogen oxide. A gas stream may comprise other acidic gases such
as, carbon dioxide. These and other acidic gases can react with a
functional group on the immobilized amine, or form compounds that
can react with the functional groups, permanently altering the
functional group and diminishing the sorbents regenerable sorbent
capacity or decomposing the immobilized amine. It has been found
that degradation of the amine functional groups can be inhibited
with the addition of an inorganic base. An inorganic base may
comprise any of the carbonates, bicarbonates, or hydroxyls of any
alkali metal or alkali-earth metal. Some non-limiting examples of
inorganic bases include Na.sub.2CO.sub.3 and NaOH.
[0028] A sorbent formulation can contain a solid support, an
adhesive, an amine, an alcohol species, and an inorganic base. The
solid support can be selected based on considerations such as its
chemically inert nature with respect to the amine functional group
The particles of the solid support can be porous or non-porous and
may comprise, for example and without limitation, oxides, such as
SiO.sub.2, alumina, calcia, magnesia, or mixtures thereof; metals,
for example and without limitation, iron, aluminum, aluminum
alloys, steel, steel alloys; carbon materials, for example and
without limitation, activated carbon; or combinations thereof.
[0029] The composition can be prepared by mixing the ingredients
and impregnating the mixture onto a solid support using
impregnation methods known in the art. A solvent can be employed to
dissolve the ingredients for thorough mixing, and later removed to
allow the adhesive to cure. Solvents may comprise water, organic
solvents such as alcohols, ketones, tetrahydrofuran (THF),
chlorinated hydrocarbons, aliphatic and aromatic hydrocarbons, or
combinations thereof In certain embodiments, a solvent may be used
to wash the solid support to remove excess or un-reacted amine,
adhesive, alcohol species and inorganic base. If pellets or
granules are desired instead of a powder, the adhesive can be
allowed to bond not only between neighboring amine molecules on the
same solid support particle, but across particles to bond particles
together. A polymer template can be employed to achieve pellets or
granules of the desired morphology. The polymer used as a template
should not be reactive toward the amine employed on the sorbent or
the adhesive. Some non-limiting examples of polymer templates can
be, PEG500, polyvinyl alcohol, or any other water-soluble polymers,
or mixtures thereof. Following curing of the amine/adhesive around
the polymer template, the polymer template can be washed off to
produce void space, serving as macropores and/or micropores to
facilitate diffusion of a compound through the sorbent. The entire
process can be completed at temperatures between -196.degree. C.
and 250.degree. C.
[0030] The present subject matter provides for employing the
desorption modified immobilized amine regenerable solid sorbent in
a gas stream. The sorbent is placed into the gas stream at an
operating temperature. The operating temperature can be between
20.degree. C. and 80.degree. C., or between 30.degree. C. and
70.degree. C., or even between 40.degree. C. and 60.degree. C. The
sorbent can reside in the gas stream until an amount of a desired
compound has adsorbed onto the sorbent. The sorbent may then heated
to a temperature above the modified desorption temperature of the
chemically adsorbed compound, but below the decomposition threshold
temperature of the immobilized amine in the sorbent. Immobilized
amines can begin decomposing at around 120.degree. C. and the
present subject matter allows desorption to occur between
60.degree. C. and 120.degree. C., or 70.degree. C. and 110.degree.
C., or 80.degree. C. and 100.degree. C. When the compound has been
sufficiently, fully or partially, desorbed and the amine functional
groups are sufficiently, fully or partially, regenerated, the
sorbent may be placed back into the gas stream for further
adsorption.
[0031] In certain embodiments, the subject matter can be used to
remove SO.sub.2 from flue gas. In an un-modified immobilized amine
sorbent, the desorption threshold temperature of SO.sub.2 can be
greater than 180.degree. C., which would cause the decomposition of
the un-modified immobilized amine. Creating an immobilized amine
with an alcohol species such as polyethylene glycol makes it
possible to desorb SO.sub.2 at less than 100.degree. C. In certain
embodiments, the subject matter can be used to remove CO.sub.2 from
flue gas. By causing CO.sub.2 to be adsorbed in the presence of a
polyethylene glycol, CO.sub.2 can be desorbed at temperatures as
low as 70.degree. C.
[0032] The removal of multiple components from a gas stream is also
contemplated. A sorbent prepared to handle the challenges of a
multi-component gas stream can include a porous solid support with
a non-porous surface area. A first composition of an amine, an
adhesive, an alcohol species and an inorganic base can be
impregnated into the pores of the solid support. A second
composition of an amine, an adhesive, an alcohol species and an
inorganic base can be impregnated onto the pore mouths and
non-porous surface area of the solid support. To keep the second
composition out of the pores, the pores can be filled with a
solvent, such as, without limitation, water or an organic solvent,
after the pores are impregnated with the first composition. When
the second composition has been impregnated and cured, the solvent
in the pores can be removed, for example, by drying. In addition,
before impregnation of the second composition, the first
composition can be treated with the compound desired to be adsorbed
to allow the amine functional groups to bind with the compound.
This dual amine structure can be used to target specific compounds
desired to be adsorbed from the gas stream, or for targeting a
specific compound while providing alternative sites for adsorbing
compounds that would otherwise interfere with the adsorption of the
specific compound.
[0033] In certain embodiments, a sorbent is prepared to handle the
challenges of removing CO, from flue gas containing sulfur
compounds and nitrogen compounds. A first immobilized composition
is prepared containing an aliphatic amine, a bisphenol epoxy, a
polyethylene glycol and Na.sub.2CO.sub.3. The ingredients are
dissolved in ethanol (EtOH) and impregnated into the pores of a
SiO.sub.2 support. The EtOH is removed by evaporation and the epoxy
is allowed to cure, immobilizing the amine. The particles are
treated with CO.sub.2 to allow the amine functional groups to bind
with CO.sub.2 molecules. The pores are then filled with water to
just below the pore mouths and a second composition is prepared.
The second composition contains an aromatic amine, a bisphenol
epoxy, polyethylene glycol and Na.sub.2CO.sub.3. The second
composition is dissolved in EtOH and impregnated onto the pore
mouths and non-porous surface area of the SiO.sub.2 particles. The
EtOH is removed and the second composition is allowed to cure. The
water is removed from the pores and the sorbent is ready to remove
CO.sub.2. In this embodiment, the dual amine structure allows
CO.sub.2 to adsorb onto the immobilized amine within the pores,
while providing sites on the immobilized amine support surface and
pore mouths for the adsorption of sulfur compounds and sulfur
by-products as well as nitrogen compounds that would otherwise
interfere with the adsorption of the CO.sub.2.
[0034] It will be apparent to those skilled in the art that there
may be changes and modifications made to the embodiments described
in the examples without departing from the general scope of the
provided subject matter. The provided subject matter is intended to
include all such modifications and alterations in so far as they
come within the scope of the appended claims or the equivalents
thereof.
EXAMPLES
Example 1
Preparation of Novel Regenerable Solid Sorbent Formulation
[0035] Preparation of 10 g of "TPS 24/36/40"
[0036] 6 g of TEPA (tetraethylene pentamine) was stirred with 9 g
of PEG (polyethylene glycol 200). A roughly equal volume of EtOH
(ethanol) was added to beaker with stirring. The mixture was then
poured onto log Silica and stirred until the sorbent was coated
properly. The mixture may look like lemon slush when coated
properly. The sorbent was then baked at 100.degree. C. until all of
the EtOH has evaporated.
[0037] Epoxy Doping
[0038] 0.444 g of an epoxy adhesive (EPON) was dissolved in 6-7 g
EtOH. A hot plate at 70.degree. C. was employed to help
dissolution. The EPON/EtOH mixture was then poured on the 10 g of
TPS 24/36/40 and uniformly mixed and baked at 100.degree. C. until
all of the EtOH was evaporated.
[0039] Na.sub.2CO.sub.3 Addition
[0040] One log of epoxy doped sorbent (the sorbent is denoted as
TPS 24/36/40--0.222Epon) is weighed out and combined with 0.1 g
Na.sub.2CO.sub.3 dissolved in 6 g of water. The mixture was stirred
until all sorbent was coated and then baked in an oven at
100.degree. C. until all the water evaporated. When all water
evaporated, the final product was an opaque white.
Example 2
Preparation and Determination of Regenerable SO.sub.2 and CO.sub.2
Capture Capacity of Novel Regenerable Solid Sorbent Composition
[0041] A procedure similar to that of example 1, using a sequential
impregnation method and a different sequence was used to prepare
four sorbents using two different silica, a granular silica (A) and
a powder silica (B). The amount of the raw materials used is listed
in Table 1.
TABLE-US-00001 TABLE 1 Compositions of the sorbents prepared in
weights Sample label EPON TEPA PEG Ethanol Si02 Na.sub.2CO.sub.3
Water TPS(A)-E 24/36/40-100 + Na.sub.2CO.sub.3 0.355 0.96 1.44 4
1.6 0.4 2.4 TPS(A)-E 36/24/40-100 + Na2CO.sub.3 0.267 1.44 0.96 6
1.6 0.4 2.4 TPS(B)-E 24/36140-100 + Na.sub.2CO.sub.3 0.355 0.96
1.44 4 1.6 0.4 2.4 TPS(B)-E 36/24/40-100 + Na.sub.2CO.sub.3 0.267
1.44 0.96 6 1.6 0.4 2.4
[0042] Preparation of TPS(A) 24/36/40 (for Roughly 4 g)
[0043] Mixed the epoxy (EPON) with TEPA and stirred until the EPON
dissolved in the TEPA. Added PEG to the EPON/ TEPA mixture and
stirred well. Impregnated the mixture onto silica and added ethanol
to the silica slurry. The sorbent was heated in an oven at
100.degree. C. to evaporate excess ethanol.
[0044] Na.sub.2CO.sub.3 Addition
[0045] Dissolved 0.04 g of Na2CO.sub.3 in water and impregnated the
Na.sub.2CO.sub.3 solution onto the above sorbent. The sorbent was
heated in an oven at 100.degree. C. to evaporate excess water to
obtain an opaque white sorbent.
[0046] The SO.sub.2 and CO.sub.2 capture capacity of these sorbents
was determined by the following procedures. In each run, the
sorbents were heated for seven minutes in an oven at 100.degree. C.
to remove any adsorbed species CO.sub.2 from the ambient
atmosphere. The samples were then saturated with 99% SO.sub.2 or
pure CO.sub.2 in continuous flow for 10 minutes. The difference in
the weight of the sample before and after the capturing was the
amount of SO.sub.2 or CO.sub.2 captured by the particular sorbent.
These sorbents were again heated in an oven at 100.degree. C. to
remove the saturated CO.sub.2 and further tested for capture
capacity. Ten runs are carried out and the SO.sub.2 or CO.sub.2
captured in each individual cycle is calculated. The tested
sorbents were kept in oven at 100.degree. C. overnight for
evaluation of thermal degradation. These sorbents were further
evaluated for SO.sub.2 capture for 3 cycles on day 2 and day 3. The
sorbent prepared with powder SiO.sub.2 and 24% TEPA and 36% PEG
showed the highest SO.sub.2 capture capacity after three days of
degradation studies. The results of SO.sub.2 capture for each run
are presented in the graph in FIG. 1 and the results for CO.sub.2
capture are presented in the graph in FIG. 2.
[0047] The data in FIG. 2 represent one of the best sets of data
obtained from more than 50 sorbents prepared and tested. These
sorbents were subjected to more 35 hours of thermal degradation
study at 100.degree. C. in air. In this study, the adsorption of
CO.sub.2 was carried out at 30.degree. C. and desorption at
100.degree. C. The CO.sub.2 capture capacity was measured before,
during, and after thermal degradation studies.
[0048] Two of the above sorbents have also been tested by ADA
Environmental Solution ( ) by adsorption at 55.degree. C. with 12%
CO.sub.2, 4% O.sub.2, balance N.sub.2 and desorption at
80-95.degree. C. The CO.sub.2 capture capacity and stability
results obtained by ADA were consistent with those reported in FIG.
2.
[0049] With respect to CO.sub.2 capture, we are able to prepare a
solid amine sorbent with CO.sub.2 capture capacity of more than 1.5
mmol/g. The sorbent did not degrade under more than 35 hour of
thermal treatment. It is expected that this sorbent will sustain
more than 500 CO.sub.2 adsorption/desorption cycles without
significant degradation.
Example 2
CO.sub.2, SO.sub.2, H.sub.2S and NO Capture Over
M-Phenyldiamine/PEG/EPON/SiO.sub.2 Sorbents
[0050] The following examples show that
m-phenyldiamine/PEG/EPON/SiO.sub.2+Na.sub.2CO.sub.3 sorbents
exhibited capture capacity for CO.sub.2, SO.sub.2, H.sub.2S, and
NO. M-phenyldiamine is an aromatic amine. PEG is a glycol, EPON is
an epoxy.
[0051] Experimental
[0052] Sorbent Preparation
[0053] For convenience the chemicals in the present study are
abbreviated as follows, polyethylene glycol-200 (PEG; P) EPON-826
(EPON; E), m-phenyldiamine (Ph), SiO.sub.2 (S). Two forms of silica
were used in this study Tixosil 68 (A) and (B). The sorbent are
abbreviated in the following notation and abbreviated as
PhPS-E.sub.10 24/36/50+Na.sub.2CO.sub.3 for 24 wt % Ph-36 wt % P-40
Wt % S-E.sub.(10-mole ratio or EPON/TEPA)+Na.sub.2CO.sub.3.
[0054] The m-phenyldiamine/PEG/EPON/SiO.sub.2+Na.sub.2CO.sub.3
sorbents were prepared by dissolving EPON in PEG/ethanol solution
under stirring for 5 min followed by addition of m-phenyl diamine
pellets. Silica was impregnated with the above mixture and dried in
oven at 100.degree. C. for 15-20 min until excess ethanol is
evaporated. Aqueous solution of Na.sub.2CO.sub.3 was added to the
solid sorbent and dried in oven at 100.degree. C. for 15-20 min to
remove the excess water. The specific compositions of sorbents are
presented in Table 2.
TABLE-US-00002 TABLE 2 The composition of the different components
used in the preparation of sorbents. Sample label Ph (g) PEG (g)
SiO.sub.2 (g) EPON (g) Na.sub.2CO.sub.3 (g) Water (g) Ethanol (g)
PhPS(A)-E.sub.20 24/36/40-100 + Na.sub.2CO.sub.3 2.4 3.6 4 0.444
0.04 2.4 1 PhPS(A)-E.sub.10 36/24/40-100 + Na.sub.2CO.sub.3 3.6 2.4
4 0.666 0.04 2.4 1 PhPS(B)-E.sub.20 24/36/40-100 + Na.sub.2CO.sub.3
2.4 3.6 4 0.444 0.04 2.4 2.5 PhPS(B)-E.sub.10 36/24/40-100 +
Na.sub.2CO.sub.3 3.6 2.4 4 0.666 0.04 2.4 2.5 *removed upon
drying
[0055] CO.sub.2 Capture
[0056] The CO.sub.2 capture capacity of the sorbents is determined
by the following procedures. In each run, the sorbents are heated
for seven min in an oven at 100.degree. C. to remove any adsorbed
CO.sub.2 from the ambient atmosphere. Then the samples are
saturated with pure CO.sub.2 in continuous flow for 10 min. The
difference in the weight of the sample before and after the
CO.sub.2 capture is considered as the amount of CO.sub.2 captured
by the particular sorbent. The sorbents are again heated in oven at
100.degree. C. to remove the captured CO.sub.2 and repeat the above
steps for further CO.sub.2 capture capacity. The SO.sub.2,
H.sub.2S, and NO capture capacity are determined in the same
procedures.
[0057] Results and Discussion
[0058] FIG. 3 and Table 3 show the CO.sub.2 capture capacity over m
phenyldiamine/PEG/EPON/SiO.sub.2+Na.sub.2CO.sub.3 sorbents. The
capture capacity marginally increases during the first day.
Treatment of the sorbents in oven at 100.degree. C. for 15 h and
retested for CO.sub.2 capture resulted in an increase in the
CO.sub.2 capture capacity. Further treatment in oven at 100.degree.
C. for another 15 h resulted in a small increase in the CO.sub.2
capture capacity. The increase in CO.sub.2 capture capacity is more
prominent in case of SiO.sub.2 (B) support.
[0059] FIG. 4 and Table 4 show the SO.sub.2 capture over
m-phenyldiamine/PEG/EPON/SiO.sub.2+Na.sub.2CO.sub.3 sorbents. The
PhPS (B)-E 24/36/40-100+Na.sub.2CO.sub.3 sorbent exhibits the
highest SO.sub.2 capture capacity. No further heat treatment was
performed on these sorbents.
[0060] FIG. 5 and Table 5 shows the H2S capture capacity over m
phenyldiamine/PEG/EPON/SiO2+Na.sub.2CO.sub.3 sorbents. The capture
capacity remains constant on three run.
[0061] FIG. 6 and Table 6 shows NO capture capacity over
m-phenyldiamine/PEG/EPON/SiO.sub.2+Na.sub.2CO.sub.3 sorbents. The
capture capacity remains constant on three run.
[0062] CO.sub.2 Capture
TABLE-US-00003 TABLE 3 Results of CO.sub.2 capture of the
m-phenyldiamine/PEG/EPON/SiO.sub.2 + Na.sub.2CO.sub.3 sorbents in
three successive days. CO.sub.2 Capture (mmol)/g mol CO.sub.2/mol
Ph Sorbent Run 1 Run 2 Run 3 Run 1 Run 2 Run 3 Day 1 (Fresh
samples) PhPS(A)-E.sub.20 24/36/40-100 + Na.sub.2CO.sub.3 0.254
0.278 0.280 0.028 0.031 0.031 PhPS(A)-E.sub.10 36/24/40-100 +
Na.sub.2CO.sub.3 0.322 0.207 0.374 0.035 0.023 0.042
PhPS(B)-E.sub.20 24/36/40-100 + Na.sub.2CO.sub.3 0.248 0.272 0.296
0.027 0.029 0.032 PhPS(B)-E.sub.10 36/24/40-100 + Na.sub.2CO.sub.3
0.258 0.259 0.331 0.029 0.029 0.037 Day 2 (after first thermal
degradation at 100.degree. C. for 15 h) PhPS(A)-E.sub.20
24/36/40-100 + Na.sub.2CO.sub.3 0.399 0313 0.399 0.054 0.043 0.054
PhPS(A)-E.sub.10 36/24/40-100 + Na.sub.2CO.sub.3 0.458 0.372 0.429
0.063 0.051 0.059 PhPS(B)-E.sub.20 24/36/40-100 + Na.sub.2CO.sub.3
0.383 0.384 0.287 0.058 0.059 0.044 PhPS(B)-E.sub.10 36/24/40-100 +
Na.sub.2CO.sub.3 0.376 0.406 0.377 0.052 0.056 0.052 Day 3 (after
second thermal degradation ai 100.degree. C. for 15 h)
PhPS(A)-E.sub.20 24/36/40-100 + Na.sub.2CO.sub.3 0.435 0.493 0.406
0.060 0.069 0.056 PhPS(A)-E.sub.10 36/24/40-100 + Na.sub.2CO.sub.3
0.451 0.331 0.391 0.065 0.048 0.056 PhPS(B)-E.sub.20 24/36/40-100 +
Na.sub.2CO.sub.3 0.559 0.493 0.528 0.088 0.078 0.083
PhPS(B)-E.sub.10 36/24/40-100 + Na.sub.2CO.sub.3 0.514 0.484 0.423
0.074 0.070 0.061
[0063] SO.sub.2 Capture
TABLE-US-00004 TABLE 4 Results of SO.sub.2 capture on
m-phenyldiamine/PEG/EPON/SiO.sub.2 + Na.sub.2CO.sub.3 sorbents Day
1 (fresh samples) SO.sub.2 Capture (mmol/g) mol SO.sub.2/mol Ph
Sorbent Run 1 Run 2 Run 3 Run 1 Run 2 Run 3 PhPS(A)-E.sub.20 1.698
1.537 1.257 0.186 0.168 0.138 24/36/40-100 + Na.sub.2CO.sub.3
PhPS(A)-E.sub.10 1.231 1.032 1.080 0.137 0.114 0.120 36/24/40-100 +
Na.sub.2CO.sub.3 PhPS(B)-E.sub.20 1.890 1.844 1.297 0.211 0.206
0.145 24/36/40-100 + Na.sub.2CO.sub.3 PhPS(B)-E.sub.10 1.424 1.324
1.260 0.161 0.149 0.142 36/24/40-100 + Na.sub.2CO.sub.3
[0064] H.sub.2S Capture
TABLE-US-00005 TABLE 5 Results of H.sub.2S capture on
m-phenyldiamine/PEG/EPON/SiO.sub.2 + Na.sub.2CO.sub.3 sorbents Day
1 (Fresh samples) H.sub.2S Capture (mmol)/g mol H.sub.2S/mol Ph
Sorbent Run 1 Run 2 Run 3 Run 1 Run 2 Run 3 PhPS(A)-E.sub.20 0.645
0.526 0.439 0.070 0.057 0.048 24/36/40-100 + Na.sub.2CO.sub.3
PhPS(A)-E.sub.10 0.570 0.480 0.450 0.063 0.053 0.050 36/24/40-100 +
Na.sub.2CO.sub.3 PhPS(B)-E.sub.20 0.623 0.563 0.505 0.068 0.062
0.056 24/36/40-100 + Na.sub.2CO.sub.3 PhPS(B)-E.sub.10 0.592 0.594
0.506 0.065 0.065 0.056 36/24/40-100 + Na.sub.2CO.sub.3
[0065] NO Capture
TABLE-US-00006 TABLE 6 Results of NO capture on
m-phenyldiamine/PEG/EPON/SiO.sub.2 + Na.sub.2CO.sub.3 sorbents NO
Capture (mmol/g) mol NO/mol Ph Sorbent Run 1 Run 2 Run 3 Run 1 Run
2 Run 3 PhPS(A)-E.sub.20 0.675 0.607 0.508 0.074 0.067 0.056
24/36/40-100 + Na.sub.2CO.sub.3 PhPS(A)-E.sub.10 0.622 0.588 0.381
0.070 0.066 0.043 36/24/40-100 + Na.sub.2CO.sub.3 PhPS(B)-E.sub.20
0.471 0.607 0.439 0.052 0.067 0.048 24/36/40-100 + Na.sub.2CO.sub.3
PhPS(B)-E.sub.10 0.631 0.666 0.534 0.068 0.072 0.058 36/24/40-100 +
Na.sub.2CO.sub.3
[0066] In the preceding description, where a range of values has
been provided, it is understood that each intervening value between
the upper and lower limit of that range and any other stated or
intervening value in that stated range is encompassed within the
subject matter. Unless defined otherwise, all technical and
scientific terms used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
subject matter belongs. Although any methods and materials similar
or equivalent to those described herein can also be used in the
practice or testing of the present subject matter, a limited number
of the exemplary methods and materials are described herein.
[0067] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
referents unless the context clearly dictates otherwise.
* * * * *