GB2483245A - Polymer membrane for carbon capture - Google Patents
Polymer membrane for carbon capture Download PDFInfo
- Publication number
- GB2483245A GB2483245A GB1014475.6A GB201014475A GB2483245A GB 2483245 A GB2483245 A GB 2483245A GB 201014475 A GB201014475 A GB 201014475A GB 2483245 A GB2483245 A GB 2483245A
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- United Kingdom
- Prior art keywords
- membrane
- gas
- accordance
- polymer
- microporous
- Prior art date
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title description 3
- 229910052799 carbon Inorganic materials 0.000 title description 3
- 229920005597 polymer membrane Polymers 0.000 title 1
- 239000012528 membrane Substances 0.000 claims abstract description 74
- 229920000642 polymer Polymers 0.000 claims abstract description 63
- 239000006096 absorbing agent Substances 0.000 claims abstract description 45
- 239000000203 mixture Substances 0.000 claims abstract description 36
- 239000007788 liquid Substances 0.000 claims abstract description 29
- 229920002313 fluoropolymer Polymers 0.000 claims abstract description 25
- 239000004811 fluoropolymer Substances 0.000 claims abstract description 22
- 238000010521 absorption reaction Methods 0.000 claims abstract description 21
- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- 239000004743 Polypropylene Substances 0.000 claims abstract description 7
- 229920001155 polypropylene Polymers 0.000 claims abstract description 7
- -1 polypropylene Polymers 0.000 claims abstract description 5
- 229920001169 thermoplastic Polymers 0.000 claims abstract description 5
- 239000004416 thermosoftening plastic Substances 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 76
- 238000000034 method Methods 0.000 claims description 25
- 230000000694 effects Effects 0.000 claims description 15
- 239000011148 porous material Substances 0.000 claims description 14
- 230000008569 process Effects 0.000 claims description 10
- 239000002250 absorbent Substances 0.000 claims description 9
- 230000002745 absorbent Effects 0.000 claims description 9
- 239000004812 Fluorinated ethylene propylene Substances 0.000 claims description 6
- 229920009441 perflouroethylene propylene Polymers 0.000 claims description 6
- 239000003153 chemical reaction reagent Substances 0.000 claims description 5
- 239000012982 microporous membrane Substances 0.000 claims description 5
- HQQADJVZYDDRJT-UHFFFAOYSA-N ethene;prop-1-ene Chemical group C=C.CC=C HQQADJVZYDDRJT-UHFFFAOYSA-N 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- 238000003181 co-melting Methods 0.000 claims description 2
- 238000001125 extrusion Methods 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 238000000465 moulding Methods 0.000 claims description 2
- 230000001419 dependent effect Effects 0.000 claims 1
- 150000001412 amines Chemical class 0.000 description 17
- 239000000463 material Substances 0.000 description 17
- 238000001764 infiltration Methods 0.000 description 12
- 230000008595 infiltration Effects 0.000 description 12
- 238000000926 separation method Methods 0.000 description 12
- 239000000047 product Substances 0.000 description 9
- 239000012071 phase Substances 0.000 description 8
- 238000002485 combustion reaction Methods 0.000 description 7
- 239000003546 flue gas Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 239000007795 chemical reaction product Substances 0.000 description 4
- 239000000446 fuel Substances 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000012856 packing Methods 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 239000002803 fossil fuel Substances 0.000 description 3
- 238000009736 wetting Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 230000003542 behavioural effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000000567 combustion gas Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 238000009420 retrofitting Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000012876 carrier material Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000001010 compromised effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002169 ethanolamines Chemical class 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- CRVGTESFCCXCTH-UHFFFAOYSA-N methyl diethanolamine Chemical class OCCN(C)CCO CRVGTESFCCXCTH-UHFFFAOYSA-N 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 229920005630 polypropylene random copolymer Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000005200 wet scrubbing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/24—Dialysis ; Membrane extraction
- B01D61/246—Membrane extraction
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
- B01D53/229—Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/26—Polyalkenes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/26—Polyalkenes
- B01D71/262—Polypropylene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/30—Polyalkenyl halides
- B01D71/32—Polyalkenyl halides containing fluorine atoms
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/10—Homopolymers or copolymers of propene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/10—Homopolymers or copolymers of propene
- C08L23/12—Polypropene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/10—Homopolymers or copolymers of propene
- C08L23/14—Copolymers of propene
- C08L23/142—Copolymers of propene at least partially crystalline copolymers of propene with other olefins
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
- C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
- B01D2252/20—Organic absorbents
- B01D2252/204—Amines
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
- B01D53/1475—Removing carbon dioxide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/18—Absorbing units; Liquid distributors therefor
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Medicinal Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Urology & Nephrology (AREA)
- Water Supply & Treatment (AREA)
- Crystallography & Structural Chemistry (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
A microporous gas absorber membrane has a polymer composition comprising a major part of a first component polymer comprising a melt-processable thermoplastic carrier of a substantially unfluorinated polyalkane (e.g. polypropylene), and a minor part of a second component polymer comprising a polymer melt-processable fluoropolymer. The membrane is preferably used in a gas/ liquid absorption/ reaction system comprising a gas/ liquid absorption/ reaction vessel having a vessel wall defining a volume containing a microporous gas absorber membrane such that liquid flows in use within the volume on a first side of the membrane, and a gas flows in use within the volume on a second side of the membrane.
Description
MEMBRANE
The invention relates to a membrane for gas! liquid exchange, in particular for use in a process system that makes use of an absorbent liquid reagent to effect the removal of a target gas from a gas phase. The invention additionally relates to a method of production of the same, and to a polymer composition for use in the method.
In the particular preferred case the invention relates to a column structure for an absorption column comprising a containment vessel for use with an absorbent liquid reagent to effect the removal of a target gas from a gas phase, the membrane serving as a gas! liquid exchange membrane therein.
The invention relates in particular to the removal of CO2 from a gas phase by means of absorption. The invention relates to a column structure for removing CO2 from a gas phase by means of absorption. The invention is particularly suitable for use in removing CO2 from the flue gases of thermal power plants fired by carbonaceous fossil fuels, both as new build and for retrofitting into existing thermal power plants.
Most of the energy used in the world today is derived from the combustion of carbonaceous fossil fuels, such as coal, oil, and natural gas. Post-combustion carbon capture (PCC) is a means of mitigating the effects of carbonaceous fuel combustion emissions by capturing CO2 from large sources of emission such as thermal power plants which use carbonaceous fuel combustion as the power source. The CO2 is not vented to atmosphere but instead is removed from flue gases by a suitable absorber and stored away from the atmosphere. Other industrial processes where similar principles might be applicable to capture post-process CO2 might include removal of CO2 generated in a process cycle, for example removal of CO2 from the process flow during production of ammonia, removal of CO2 from a natural gas supply etc. It is known that CO2 can be separated from a gas phase, for example being the flue gas of a thermal power plant, by means of absorption by passing the gas through a column where the gas flows in an opposite direction to an absorbent in liquid phase. Such a process is sometimes referred to as wet scrubbing. A well known absorbent reagent comprises one or more amines in water.
Packed tower absorber column technology is well established to exploit this. An absorption plant consists of at least one column where liquid absorber is run through the column as the gas that is to be scrubbed is passed in the other direction. Typical columns consist of multiple sections of structured packing consisting of multiple thin plates or like structures to maximize the surface area for mass transfer. These are stacked within a containment vessel of steel or other suitable structural material. Such structures can be cumbersome and heavy.
Microporous gas absorber membrane (CAM) contactors are known. These initially appear to be feasible in principle as an interface means for gas/ liquid systems for FCC and the like, and potentially far more efficient than packing columns, but in practice they tend to suffer from rapid performance deterioration due to capillary infiltration into the micropores. A microporous gas absorber membrane that could mitigate the effect of such capillary infiltration would be desirable.
In accordance with the invention in a first aspect, a microporous gas absorber membrane comprises: a polymer composition comprising a major part of a first component polymer comprising a melt-processable substantially unfluorinated polyalkane, and a minor part of a second component polymer comprising a polymer melt-processable fluoropolymer; the said composition comprising the microporous membrane, and in particular the said composition having been melt processed and formed into a microporous gas absorber membrane.
Such a membrane is found to mitigate the capillary infiltration problem of as a surprising consequence of the tendency of such a mixed composition to segregate with time as the first and second component polymers separate and for the minor component to migrate to the surface. This effect can be best understood by referring to the capillary infiltration problem in more detail with reference to figure 2, where the action of a membrane acting as a microporous gas absorber membrane (GAM) contactor in a typical CO2 with amine absorber chemistry known from existing systems for PCC from the combustion gases of carbonaceous fuel combustion is considered.
In Scenario 1 there is no significant capillary infiltration. Reaction of CO2 with amine takes place at the membrane surface. Reaction products (i.e. rich amine) are quickly swept away within the freely circulating amine stream, so that equilibrium conditions are not achieved.
In Scenario 2, there is significant capillary infiltration and reaction of CO2 with amine takes within the pore, due to capillary infiltration. Reaction products now have to diffuse along a lengthy corridor of stagnant amine solution, compromising the driving force for further reaction, and the material's ability to function as a membrane.
Resistance to capillary infiltration on the liquid side is thus of great significance to the effectiveness of the reaction process. However, a dense network of narrow pores remains desirable on the free gas flow side. Resistance to capillary infiltration is partly a question of pore size (liquids cannot penetrate in below a certain critical diameter) and partly a question of surface wetting (an aqueous liquid will not penetrate the sub-microscopic features of a sufficiently low energy surface. The ideal material would have a dense network of narrow pores and also have a low surface energy.
No one polymeric material combines these two properties, but in accordance with the invention it is possible to compound minor quantities of the second polymer to provide the low surface energy with major quantities of the first polymer selected for well understood bulk properties, in particular being readily formable into a structure with a dense network of narrow pores. The two components are powdered, then co-melted and formed into a final extruded/moulded shape.
As the skilled person will appreciate, the co-melt process is distinctively characteristic of the resultant product. it is necessary to produce the resultant product and distinctly characterises the structure of the resultant product.
The invention additionally relies upon a surprising exploitation of a usually undesired side effect of such a co-melted membrane product. Over time as the co-melted membrane product ages the first and second component polymers separate and the fluoropolymer component tends to migrate to the surface. This process is normally seen as a degradation, but in the present invention is exploited. With appropriate selection of materials for the compositions envisaged by the invention, this effect can be designed to be produced relatively quickly, in days for example. In the resultant product, the polyalkane component tends to have a dominant bulk effect and acts in effect as a thermoplastic carrier material. The fluoropolymer component tends to have a disproportionate surface effect without substantive detriment to the bulk carrier polymer properties, and in particular without substantive detriment to its ability to form a dense network of narrow pores. The segregated co-melted material can get nearer to the ideal of a dense network of narrow pores and a low surface energy.
The co-melted membrane product may be allowed to segregate prior to use by passage of time or by other control process such as heat-treating.
For the compositions envisaged by the present invention, a storage time of about a week may be sufficient. Thus, what is normally an undesirable behavioural property of co-melted compositions, leading to reduction in performance during use, becomes in the particular case of the invention a desirable behavioural property leading to improvement in performance before use.
In accordance with the invention in a second aspect there is provided a melt-processable polymer composition for a microporous membrane comprising a major part of a first component polymer comprising a melt-processable substantially unfluorinated polyalkane, and a minor part of a second component polymer comprising a polymer melt-processable fluoropolymer.
The polymer composition is suitable to be formed into a microporous gas absorber membrane in accordance with the invention in the first aspect.
In accordance with the invention in a further aspect there is provided a method of forming a microporous gas absorber membrane comprising the steps of: co-melting a polymer composition comprising a major part of a first component polymer comprising a melt-processable substantially unfluorinated polyalkane, and a minor part of a second component polymer comprising a polymer melt-processable fluoropolymer; forming the resultant co-melt into a microporous gas absorber membrane, for example by extrusion and! or moulding.
The method is suitable for fabrication of a microporous gas absorber membrane in accordance with the invention in the first aspect. In particular, it is an inherent property of the product of the method that the first and second component polymers tend to separate and the fluoropolymer component tends to migrate to the surlace. Preferably, the method comprises the further step of allowing or encouraging this separation effect after the microporous gas absorber membrane is fabricated.
In selecting materials suitable for the first and second aspects of the invention above, the first component polymer that forms the major part of the composition is selected to provide the predominant bulk properties in the melt co-processing stage of fabrication. The first component polymer is also selected for its ability to form membrane structures with a dense network of narrow pores.
The first component polymer comprises for example a melt processable thermoplastic polyalkane. The first component polymer may be comprise single or multiple constituent melt processable thermoplastic polyalkanes.
The first component polymer conveniently comprises a semi-crystalline (spherulitic crystallite structure) polyalkane.
The first component polymer is a substantially non-fluorinated polyalkane.
Preferably the first component polymer is entirely non-fluorinated.
Preferably the first component polymer is a substantially non-substituted polyalkane. Preferably, all (C-X) terminal atoms are Hydrogen.
Such a polymer is selected to be able to co-mingle with the fluorinated polymer species in an agitated melt but subsequently reject it from the solidified structure. PolyPropylene is particularly preferred.
The second component polymer is a substantially and preferably a fully fluorinated polymer (i.e. at least a substantial number and preferably all (C-X) terminal atoms are Fluorine), able to be melt-processed. The second component polymer may be selected from one or more fluoropolymer species such as a Poly-FluoroAlkoxy (PFA) species or a Fluorinated Ethylene Propylene (FEP) species. A Poly-FluoroAlkoxy (PFA) species from the "Telfon" family is a possible material example. A speciality PolyEther functionality (i.e. polymer chain containing integral (C-O-C) linkages) may be preferred.
The key principle underlying the material combination selection is that, after co-processing the two polymers to final shape the fluoropolymer behaves like an impurity to segregate from the majority species migrating to the surface and forming a bloom that would consist mostly of fluoropolymer. This surface would thus display the low energy properties required to resist wetting.
Thus, the effect of the fluoropolymer is mitigated in the initial co-processing but maximized in the final product by exploitation of a segregation effect hitherto usually seen as only detrimental in melt co-processed polymer compositions.
The first component polymer makes up a major part of the composition.
Preferably the first component polymer comprises at least 90% by weight of the composition. The second component polymer preferably comprises 2 to 8% by weight of the composition. Each of the first and second component polymers may comprise a single species or multiple constituent species with the desired properties in a processable mixture.
Optionally, additional minor components may be included in the composition.
The membrane of the invention is particularly suited for use as a microporous gas absorber membrane in a gas! liquid absorption! reaction system.
In accordance with the invention in a further aspect there is provided a gas! liquid absorption! reaction system comprising a rnicroporous gas absorber membrane in accordance with the first aspect of the invention.
In particular, a gas! liquid absorption! reaction vessel comprises a vessel wall defining a volume containing a microporous gas absorber membrane in accordance with the first aspect of the invention such that liquid flows in use within the volume on a first side of the membrane, a gas flows in use within the volume on a second side of the membrane.
In a preferred embodiment, the vessel comprises an absorption vessel for use with an absorbent liquid reagent to effect the removal of a target gas from agas phase.
The vessel preferably comprises in particular an elongate columnar structure with longitudinally extending walls defining a closed vessel perimeter, for example being generally cylindrical, rectangular or other polygonal columnar shape. The columnar structure is preferably orientated vertically. The vessel preferably comprises a columnar structure for removing CO2 from a gas phase by means of absorption.
This embodiment is particularly suitable for use in removing 002 from the gaseous byproducts of a carbonaceous combustion process, and for example the flue gases of thermal power plants fired by carbonaceous fossil fuels. The embodiment is suitable for application to such use both as new build and for retrofitting into existing systems such as existing thermal power plants.
Thus, in the preferred embodiment the vessel is a PCC absorber column in which the microporous gas absorber membrane in accordance with the first aspect of the invention substitutes at least in part for the structured packing more familiar in the prior art in providing a high surface area separation material for mass transport at the gas! liquid interface.
The vessel may be adapted for 002 separation in familiar manner, in that 002 is separated from a gas phase, for example being the flue gas of a thermal power plant, by means of absorption by passing the gas through the vessel where the gas flows in an opposite direction to an absorbent in liquid phase, the microporous gas absorber membrane in accordance with the first aspect of the invention being disposed to provide a high surface area for mass transport at the gas! liquid interface. The vessel thus comprise means to cause 002-rich gas to flow in a first direction through the vessel and means to cause absorbent in liquid phase to flow through the vessel countercurrently thereto, with the microporous gas absorber membrane in accordance with the first aspect of the invention being disposed such that the C02-rich gas flows across a first surface and the liquid phase flows across a second surface whereby the microporous gas absorber membrane in accordance with the first aspect of the invention provides a semi-permeable membrane at the gas! liquid interface.
The separation vessel may be divided into plural sections for example transversely (such that in a vertical column sections are arrayed vertically) with the microporous gas absorber membrane disposed to provide a high surface area separation material for mass transport at the gas! liquid interface in one or more such sections. Other sections may comprise other separation materials.
It is an advantage of the invention in this embodiment that the microporous gas absorber membrane may substitute for other mass transfer elements, such as structured packing, in a CO2 separation column system which can otherwise make use of known chemistry and structures.
In a more complete embodiment, the vessel is a CO2 separation column and the internal volume of the column preferably further comprises, typically for example disposed at the top of the or each section of separation material, one or more of a collector structure, a distributor structure, and a bed limiter in familiar manner. The column may further comprise in a washing stage a demister structure. All the foregoing will be of familiar design scaled up as applicable to the larger columns made possible in the present invention.
The column preferably further comprises a means to supply absorbent solution through one or more inlets in the vicinity of the top of the column.
In the preferred application the column is a CO2 wet scrubber, and the solution may comprise one or more aqueous amines, for example including but not limited to monoethanolamines or methyl-diethanol-amines.
In the preferred application the vessel is provided for use in a scrubber column for flue gases and is provided with a flue inlet towards the bottom of the vessel.
The invention will now be described by way of example only with reference to Figures ito 2 of the accompanying drawings, wherein: figure 1 is a schematic representation of a microporous gas absorber membrane such as might embody the principles of the invention suitable for application in a CO2 separation column system; figure 2 shows the processes occurring at a membrane being employed as a microporous gas absorber membrane in a CO2 separation column system such as one making use of the microporous gas absorber membrane of figure 1 to illustrate the advantages of a polymer composition in accordance with the invention.
Figure 1 is a general schematic of the circulation of amine and flue gas through a microporous gas absorber membrane such as might embody the principles of the invention illustrated, from left to right, as an end projection, as a longitudinal section, and with an enlarged view of a short section of microporous gas absorber membrane. The membrane is intended to comprise a CAM contactor in a CO2 separation column system, the other elements of which are not specifically shown but may be of any suitable standard design as will be readily available to the person skilled in the art.
Figure 2 illustrates the action of a microporous gas absorber membrane (CAM) contactor.
This action has been discussed briefly above as it would apply in a typical 002 with amine absorber chemistry known from existing systems for P00 from the combustion gases of carbonaceous fuel combustion.
In Scenario 1, with no capillary infiltration, reaction of CO2 with amine takes place at the membrane surface. Reaction products (i.e. rich amine) are quickly swept away within the freely circulating amine stream, so that equilibrium conditions are not achieved. Mechanical circulation of the amine solution can thus be used to drive the formation of a partial 002 vacuum within the pores, resulting in an efficient, selective CAM membrane.
Conversely, in Scenario 2, reaction of 002 with amine takes within the pore, due to capillary infiltration. Reaction products now have to diffuse along a lengthy corridor of stagnant amine solution, regardless of the external flow rate. There is no longer any driving force for further reaction, and the material's ability to function as a membrane is compromised.
To balance resistance to capillary infiltration with the desire for a dense network of narrow pores, the ideal material would be suitable for forming such a dense network of narrow pores and also have a low surface energy.
No one polymeric material combines these two properties, but it can be offered in a distinct and surprising way by the compositions in accordance with the invention. Minor quantities of a fluoropolymer providing the low surface energy in the finished product are combined with major quantities (for example the balance) of a medium-to-low cost polymer selected as suitable for forming such a dense pore structure with appropriate bulk strength characteristics (e.g. polypropylene: cheap, with well understood properties, and easily manipulated) which are co-melted via a powder melt process into the desired structure.
In the initial co-processing, it is primarily the bulk properties of the majority species polymer that are exploited in forming the co-melted composition into a final extruded/moulded shape (e.g. initially a cast plaque, then a microporous membrane, ideally in tube form). The quantity of fluoropolymer is sufficiently low to avoid excessive detriment to the bulk properties of the majority species.
The key principle is that, after co-processing the two polymers to final shape, the fluoropolymer, behaving like an impurity, would segregate from the majority species migrating to the surface and forming a bloom that would consist mostly of fluoropolymer. This is allowed to happen, for example over a timescale of days or weeks, before the final product is made available for use as a microporous gas absorber membrane contactor or the like. This surface would thus display enhanced low energy properties required to resist wetting.
EXAMPLES
Example 1
In a first example composition the main component material is a semi-crystalline polypropylene-random-copolymer such as Borealis RA13OE.
This exhibits good stability at the temperatures and conditions of an amine based carbon capture system. The composition has added 5% Du Pont Teflon PFA as the fluoropolymer component.
Example 2
In a second example composition the main component is instead selected as a more highly crystalline grade of Polypropylene (PP), allowing substitution of Fluorinated Ethylene Propylene (FEP) as the fluoropolymer component.
Claims (18)
- CLAIMS1. A microporous gas absorber membrane comprising: a polymer composition comprising a major part of a first component polymer comprising a melt-processable substantially unfluorinated polyalkane, and a minor part of a second component polymer comprising a melt-processable fluoropolymer; the said composition comprising the microporous membrane.
- 2. A microporous gas absorber membrane in accordance with claim 1 wherein the said composition has been melt processed and formed into the microporous gas absorber membrane.
- 3. A microporous gas absorber membrane in accordance with claim 2 wherein the said first and second components have been powdered, co-melted and formed into a final extruded/moulded shape.
- 4. A microporous gas absorber membrane in accordance with claim 3 wherein the co-melted membrane product has been allowed to segregate prior to use by passage of time or by other control process such as heat-treating.
- 5. A melt-processable polymer composition for a microporous membrane comprising a major part of a first component polymer comprising a melt-processable substantially unfluorinated polyalkane, and a minor part of a second component polymer comprising a polymer melt-processable fluoropolymer.
- 6. A method of forming a microporous gas absorber membrane comprising the steps of: co-melting a polymer composition comprising a major part of a first component polymer comprising a melt-processable substantially unfluorinated polyalkane, and a minor part of a second component polymer comprising a polymer melt-processable fluoropolymer; forming the resultant co-melt into a microporous gas absorber membrane, for example by extrusion and! or moulding.
- 7. A method in accordance with claim 6 comprising the further step of allowing or encouraging the fluoropolymer to migrate to the surface of the microporous gas absorber membrane after the microporous gas absorber membrane is fabricated.
- 8. A membrane, composition or method in accordance with any preceding claim wherein the first component polymer is selected for its ability to form membrane structures with a dense network of narrow pores.
- 9. A membrane, composition or method in accordance with any preceding claim wherein the first component polymer comprises a semi-crystalline melt processable thermoplastic polyalkane.
- 10. A membrane, composition or method in accordance with any preceding claim wherein all (C-X) terminal atoms of the first component polymer are hydrogen.
- 11. A membrane, composition or method in accordance with any preceding claim wherein the first component polymer comprises polypropylene (PP).
- 12. A membrane, composition or method in accordance with any preceding claim wherein the second component polymer is a substantially fluorinated polymer.
- 13. A membrane, composition or method in accordance with claim 12 wherein the second component polymer is selected from one or more fluoropolymer species such as a Poly-FluoroAlkoxy (PFA) species or a Fluorinated Ethylene Propylene (FEP) species.
- 14. A gas! liquid absorption! reaction system comprising a microporous gas absorber membrane in accordance with the membrane of one of claims I to 4 or one of claims 8 to 13 when dependent upon one of claims 1 to 4.
- 15. A gas! liquid absorption! reaction system in accordance with claim 14 comprising a gas! liquid absorption! reaction vessel having a vessel wall defining a volume containing a microporous gas absorber membrane such that liquid flows in use within the volume on a first side of the membrane, and a gas flows in use within the volume on a second side of the membrane.
- 16. A gas! liquid absorption! reaction system in accordance with claim wherein the vessel comprises an absorption vessel for use with an absorbent liquid reagent to effect the removal of a target gas from a gas phase.
- 17. A gas! liquid absorption! reaction system in accordance with claim 16 wherein the vessel comprises an elongate columnar structure with longitudinally extending walls defining a closed vessel perimeter, for example being generally cylindrical, rectangular or other polygonal columnar shape.
- 18. A gas/liquid absorption! reaction system in accordance with one of claims 15 to 17 wherein the vessel comprises a columnar structure for removing CO2 from a gas phase by means of absorption.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1014475.6A GB2483245A (en) | 2010-09-01 | 2010-09-01 | Polymer membrane for carbon capture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1014475.6A GB2483245A (en) | 2010-09-01 | 2010-09-01 | Polymer membrane for carbon capture |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB201014475D0 GB201014475D0 (en) | 2010-10-13 |
| GB2483245A true GB2483245A (en) | 2012-03-07 |
Family
ID=43013477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1014475.6A Withdrawn GB2483245A (en) | 2010-09-01 | 2010-09-01 | Polymer membrane for carbon capture |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2483245A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60172306A (en) * | 1984-02-17 | 1985-09-05 | Daikin Ind Ltd | Compound film |
| WO2001046313A1 (en) * | 1999-12-22 | 2001-06-28 | E.I. Du Pont De Nemours And Company | Extrusion aid combination |
| WO2003040232A1 (en) * | 2001-11-08 | 2003-05-15 | Dupont Dow Elastomers L.L.C. | Process aid for melt processable polymers |
| EP1378285A2 (en) * | 2002-07-01 | 2004-01-07 | Praxair Technology, Inc. | Gas separation using membranes formed from blends of perfluorinated polymers |
| CA2110440C (en) * | 1992-12-02 | 2005-02-15 | Jan-Peter Piesold | Polypropylene molding composition for producing calendered films |
| EP2025390A1 (en) * | 2006-04-28 | 2009-02-18 | Asahi Kasei Chemicals Corporation | Gas separation membrane |
-
2010
- 2010-09-01 GB GB1014475.6A patent/GB2483245A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60172306A (en) * | 1984-02-17 | 1985-09-05 | Daikin Ind Ltd | Compound film |
| CA2110440C (en) * | 1992-12-02 | 2005-02-15 | Jan-Peter Piesold | Polypropylene molding composition for producing calendered films |
| WO2001046313A1 (en) * | 1999-12-22 | 2001-06-28 | E.I. Du Pont De Nemours And Company | Extrusion aid combination |
| WO2003040232A1 (en) * | 2001-11-08 | 2003-05-15 | Dupont Dow Elastomers L.L.C. | Process aid for melt processable polymers |
| EP1378285A2 (en) * | 2002-07-01 | 2004-01-07 | Praxair Technology, Inc. | Gas separation using membranes formed from blends of perfluorinated polymers |
| EP2025390A1 (en) * | 2006-04-28 | 2009-02-18 | Asahi Kasei Chemicals Corporation | Gas separation membrane |
Also Published As
| Publication number | Publication date |
|---|---|
| GB201014475D0 (en) | 2010-10-13 |
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