# US 7,745,030 B2 · Proton-conducting polymer membrane comprising sulfonic acid-containing polyazoles, and use thereof in fuel cells > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,745,030 B2 - Document ID: US7745030B2 - Status: Granted - Kind: B2 - Application number: 10/529,993 - Filed: 2003-10-02 - Published: 2006-08-17 - Granted: 2010-06-29 - Earliest claimed: 2002-10-04 - Assignees: BASF Fuel Cell GmbH - Inventors: Oemer Uensal; Joachim Kiefer; Gordon Calundann; Michael Sansone; Brian Benicewicz; Eui Wong Choe - Web page: https://patentgrep.com/patent/US7745030B2 ## CPC - C08J 5/2256: {based on macromolecular compounds obtained by reactions other than those involving carbon-to-carbon bonds, e.g. obtained by polycondensation} - B01D 71/62: Polycondensates having nitrogen-containing heterocyclic rings in the main chain - B01D 71/82: characterised by the presence of specified groups, e.g. introduced by chemical after-treatment - C08G 73/18: Polybenzimidazoles - H01M 8/103: having nitrogen, e.g. sulfonated polybenzimidazoles [S-PBI], polybenzimidazoles with phosphoric acid, sulfonated polyamides [S-PA] or sulfonated polyphosphazenes [S-PPh] - H01M 8/1067: characterised by their physical properties, e.g. porosity, ionic conductivity or thickness - H01M 8/1072: by chemical reactions, e.g. in situ polymerisation or in situ crosslinking - Y02E 60/50: Fuel cells - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A proton-conducting polymer membrane comprising polyazoles containing sulfonic acid groups is obtainable by a process comprising: A) mixing one or more aromatic or heteroaromatic tetraamino compounds with one or more aromatic or heteroaromatic carboxylic acids or derivatives thereof which contain at least two acid groups per carboxylic acid monomer, with at least part of the tetraamino compounds or the carboxylic acids comprising at least one sulfonic acid group, or mixing of one or more aromatic or heteroaromatic diaminocarboxylic acids, of which at least part comprises sulfonic acid groups, in polyphosphoric acid to form a solution or dispersion; B) optionally heating the solution or dispersion obtained by step A) under inert gas to temperatures of up to 325° C. to form polyazole polymers; C) applying a layer using the mixture from step A) or B) to a support, thus forming a membrane, and D) partially hydrolyzing the polyphosphoric acid moieties of the membrane from step C) until it is self-supporting. ## Claims ### Claim 1 A proton-conducting polymer membrane which comprises polyazoles containing sulfonic acid groups and is obtainable by a process comprising the steps: A) mixing one or more aromatic or heteroaromatic tetraamino compounds with one or more aromatic or heteroaromatic carboxylic compounds in polyphosphoric acid to form a solution or dispersion, wherein the carboxylic compounds contain at least two carboxylic groups selected from acids, esters, acid halides or acid anhydrides, with at least part of the tetraamino compounds or the carboxylic compounds comprising at least one sulfonic acid group; or mixing one or more aromatic or heteroaromatic diaminocarboxylic compounds in polyphosphoric acid to form a solution or dispersion, wherein the diaminocarboxylic compounds contain a carboxylic group selected from acids and esters, wherein at least a part of said diaminocarboxylic compounds comprises sulfonic acid groups; B) heating the solution or dispersion obtained according to step A) under inert gas to temperatures of up to 325° C. to form polyazole polymers; and C) applying a layer using the mixture from step B) to a support, thus forming a membrane on the support; or D) applying the solution or dispersion from step A) to a support, thus forming a membrane on the support; and E) heating the membrane formed in step D) under inert gas to temperatures of up to 325° C. to form polyazole polymers; and F) partially hydrolyzing the polyphosphoric acid moieties of the membrane from step C) or step E) until the membrane is self-supporting, wherein the concentration of phosphoric acid in the membrane of step (F) is from 10 to 80 mols of phosphoric acid per mol of a repeating unit of the polyazole polymer. ### Claim 2 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises aromatic or heteroaromatic tetraamino compounds of the formula (A): wherein Ar is an aromatic or heteroaromatic group; Y is a bond or a group having from 1 to 20 carbon atoms; p is an integer from 1 to 4 and represents the number of bonds or groups Y via which the group Z is bound to the group Ar; r is an integer from 1 to 4 and represents the number of groups Z which are bound to the group Y or, if Y is a bond, to the aromatic or heteroaromatic group Ar; and Z is a group of the general formula (1): —SO3H (1); or the general formula (2): wherein R1 is a hydrogen atom or a group having from 1 to 20 carbon atoms. ### Claim 3 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises aromatic or heteroaromatic carboxylic compounds of the formula (B): wherein Ar is an aromatic or heteroaromatic group; X is a halogen atom or a group of the formula OR2, where R2 is a hydrogen atom or a group having from 1 to 20 carbon atoms; Y is a bond or a group having from 1 to 20 carbon atoms; p is an integer from 1 to 4 and represents the number of bonds or groups Y via which the group Z is bound to the group Ar; r is an integer from 1 to 4 and represents the number of groups Z which are bound to the group Y or, if Y is a bond, to the aromatic or heteroaromatic group Ar; and Z is a group of the general formula (1): —SO3H (1); or the general formula (2): wherein R1 is a hydrogen atom or a group having from 1 to 20 carbon atoms. ### Claim 4 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises aromatic or heteroaromatic tetraamino compounds which contain no sulfonic acid groups and aromatic or heteroaromatic carboxylic compounds which contain at least one sulfonic acid group. ### Claim 5 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises 3,3′,4,4′-tetraaminobiphenyl, 2,3,5,6-tetraaminopyridine, or 1,2,4,5-tetraaminobenzene. ### Claim 6 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises: isophthalic acid; terephthalic acid; phthalic acid; 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyterephthalic acid; 5-aminoisophthalic acid; 5-N,N-dimethylaminoisophthalic acid; 5-N,N-diethylaminoisophthalic acid; 2,5-dihydroxyterephthalic acid; 2,5-dihydroxyisophthalic acid; 2,3-dihydroxyisophthalic acid; 2,3-dihydroxyphthalic acid; 2,4-dihydroxyphthalic acid; 3,4-dihydroxyphthalic acid; 3-fluorophthalic acid; 5-fluoroisophthalic acid; 2-fluoroterephthalic acid; tetrafluorophthalic acid; tetrafluoroisophthalic acid; tetrafluoroterephthalic acid; 1,4-naphthalenedicarboxylic acid 1,5-naphthalenedicarboxylic acid 2,6-naphthalenedicarboxylic acid 2,7-naphthalenedicarboxylic acid diphenic acid 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid bis(4-carboxyphenyl) ether benzophenone-4,4′-dicarboxylic acid bis(4-dicarboxyphenyl) sulfone; biphenyl-4,4′-dicarboxylic acid; 4-trifluoromethylphthalic acid; 2,2-bis(4-carboxyphenyl)hexafluoropropane; 4,4′-stilbenedicarboxylic acid; 4-carboxycinnamic acid; or their C1-C20-alkyl esters or C5-C12-aryl esters, or their acid anhydrides or acid chlorides. ### Claim 7 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises 2,3-diamino-5-carboxyphenylsulfonic acid, 2,3-diamino-6-carboxyphenylsulfonic acid, and 3,4-diamino-6-carboxyphenylsulfonic acid. ### Claim 8 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises aromatic tricarboxylic compounds selected from tricarboxylic acids, their C1-C20-alkyl esters or C5-C12-aryl esters or their acid anhydrides or their acid halides or tetracarboxylic acids, their C1-C20-alkyl esters or C5-C12-aryl esters or their acid anhydrides or their acid halides. ### Claim 9 (depends on 8) The membrane of claim 8, characterized in that the mixture prepared in step A) comprises 1,3,5-benzenetricarboxylic acid (trimesic acid); 2,4,5-benzenetricarboxylic acid (trimellitic acid); (2-carboxyphenyl)iminodiacetic acid, 3,5,3′-biphehyltricarboxylic acid; 3,5,4′-biphenyltricarboxylic acid; 2,4,6-pyridinetricarboxylic acid; benzene-1,2,4,5-tetracarboxylic acid; naphthalene-1,4,5,8-tetracarboxylic acid; 3,5,3′,5′-biphenyltetracarboxylic acid; benzophenonetetracarboxylic acid; 3,3′,4,4′-biphenyltetracarboxylic acid; 2,2′,3,3′-biphenyltetracarboxylic acid; or 1,2,5,6-naphthalenetetracarboxyllic acid. ### Claim 10 (depends on 8) The membrane of claim 8, characterized in that the content of tricarboxylic acid or tetracarboxylic compounds is in the range of from 0 to 30 mol % based on dicarboxylic acid used. ### Claim 11 (depends on 10) The membrane of claim 10, characterized in that the content of tricarboxylic acid or tetracarboxylic compounds is in the range of from 0.1 to 20 mol % based on dicarboxylic acid used. ### Claim 12 (depends on 11) The membrane of claim 11, characterized in that the content of tricarboxylic acid or tetracarboxylic compounds is in the range of from 0.5 to 10 mol % based on dicarboxylic acid used. ### Claim 13 (depends on 1) The membrane of claim 1, characterized in that the mixture prepared in step A) comprises heteroaromatic dicarboxylic compounds, tricarboxylic compounds or tetracarboxylic compounds which contain at least one nitrogen, oxygen, sulfur, or phosphorus atom in the aromatics. ### Claim 14 (depends on 13) The membrane of claim 13, characterized in that mixture prepared in step A) comprises pyridine-2,5-dicarboxylic acid; pyridine-3,5-dicarboxylic acid; pyridine-2,6-dicarboxylic acid; pyridine-2,4-dicarboxylic acid; 4-phenyl-2,5-pyridinedicarboxylic acid; 3,5-pyrazoledicarboxylic acid; 2,6-pyrimidinedicarboxylic acid; 2,5-pyrazinedicarboxylic acid; 2,4,6-pyridinetricarboxylic acid; benzimidazole-5,6-dicarboxylic acid; or their C1-C20-alkyl esters or C5-C12-aryl esters or their acid anhydrides or their acid chlorides are used. ### Claim 15 (depends on 1) The membrane as claimed in claim 1, characterized in that the mixture prepared in step A) comprises diaminobenzoic acid or its monohydrochloride and dihydrochloride salts. ### Claim 16 (depends on 1) The membrane of claim 1, characterized in that the heating according to step B) is carried out after the formation of a sheet-like structure according to step C). ### Claim 17 (depends on 1) The membrane as claimed in claim 1, characterized in that the solution produced in step A) or step B) further comprises dispersed or suspended polymer. ### Claim 18 (depends on 1) The membrane of claim 1, characterized in that the treatment according to step D) is carried out at temperatures in the range of from 0° C. to 150° C. in the presence of moisture. ### Claim 19 (depends on 1) The membrane of claim 1, characterized in that the treatment of the membrane in step D) is carried out from 10 seconds to 300 hours. ### Claim 20 (depends on 1) The membrane of claim 1, characterized in that the membrane formed after step D) is crosslinked by action of oxygen. ### Claim 21 (depends on 1) The membrane of claim 1, characterized in that a layer having a thickness of from 20 to 4000 μm is produced in step C). ### Claim 22 (depends on 1) The membrane of claim 1, characterized in that the membrane formed after step D) has a thickness of from 15 to 3000 μm. ### Claim 23 (depends on 1) A membrane-electrode unit comprising at least one electrode and at least one membrane as claimed in claim 1. ### Claim 24 An electrode having a proton-conducting polymer coating which is based on polyazoles and is obtainable by a process comprising the steps: A) mixing one or more aromatic or heteroaromatic tetraamino compounds with one or more aromatic or heteroaromatic carboxylic compounds in polyphosphoric acid to form a solution or dispersion, wherein the carboxylic compounds contain at least two groups selected from acids, esters, acid halides or acid anhydrides, with at least part of the tetraamino compounds or the carboxylic compounds comprising at least one phosphonic acid group; or mixing one or more aromatic or heteroaromatic diaminocarboxylic compounds in polyphosphoric acid to form a solution or dispersion, wherein the diaminocarboxylic compounds contain a group selected from acids and esters, wherein at least a part of said diaminocarboxylic compounds comprises sulfonic acid groups; B) heating the solution or dispersion obtained according to step A) under inert gas to temperatures of up to 350° C. to form polyazole polymer; and C) applying a layer using the mixture from step B) to an electrode, thus forming a membrane on the electrode; or D) applying the solution or dispersion from step A) to an electrode, thus forming a membrane on the electrode; and E) heating the membrane formed in step D) under inert gas to temperatures of up to 325° C. to form polyazole polymers; and F) partially hydrolyzing the polyphosphoric acid moieties of the electrode membrane formed in step C) or step E), wherein the concentration of phosphoric acid in the membrane of step (F) is from 10 to 80 mols of phosphoric acid per mol of a repeating unit of the polyazole polymer. ### Claim 25 (depends on 24) The electrode of claim 24, wherein the coating has a thickness of from 2 to 3000 μm. ### Claim 26 A membrane-electrode unit comprising at least one electrode having a proton-conducting polymer coating which is based on polyazoles and is prepared by the following steps: A) mixing one or more aromatic or heteroaromatic tetraamino compounds with one or more aromatic or heteroaromatic carboxylic compounds in polyphosphoric acid to form a solution or dispersion, wherein the carboxylic compounds contain at least two groups selected from acids, esters, acid halides or acid anhydrides, with at least part of the tetraamino compounds or the carboxylic compounds comprising at least one sulfonic acid group; or mixing one or more aromatic or heteroaromatic diaminocarboxylic compounds in polyphosphoric acid to form a solution or dispersion, wherein the diaminocarboxylic compounds contain a group selected from acids and esters, wherein at least a part of said diaminocarboxylic compounds comprises sulfonic acid groups; B) heating the solution or dispersion obtained according to step A) under inert gas to temperatures of up to 350° C. to form polyazole polymer; C) applying a layer using the mixture from step B) to an electrode, thus forming a membrane on the electrode; or D) applying a solution or dispersion from step A) to an electrode, thus forming a membrane on the electrode; and E) heating the membrane formed in step D) under inert gas to temperatures of up to 325° C. to form polyazole polymers; and F) partially hydrolyzing the polyphosphoric acid moieties of the electrode membrane formed in step C) or step E) until the membrane is self-supporting, wherein the concentration of phosphoric acid in the membrane of step (F) is from 10 to 80 mols of phosphoric acid per mol of a repeating unit of the polyazole polymer. ### Claim 27 (depends on 26) A fuel cell comprising one or more membrane-electrode units as claimed in claim 26.