Poly(2,5-bibenzimidazole) Membranes: Physico-Chemical Characterization Focused on Fuel Cell Applications

Autor(es)

Linares, Jose J. ^[1] ; Sanches, Cassandra ^[1] ; Paganin, Valdecir A. ^[1] ; Gonzalez, Ernesto R. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of the Electrochemical Society; v. 159, n. 7, p. F194-F202, 2012.
• Citações Web of Science: 15

Resumo

Membranes of Poly(2,5-benzimidazole) (ABPBI), prepared by polycondensation in polyphosphoric acid, were characterized from the fuel cell application point of view: mechanical properties of the membranes for different acid doping levels, thermal stability, permeability for the different gases/vapors susceptible of use in the cell (hydrogen, oxygen, methanol and ethanol), electro-osmotic water drag coefficient, oxidation stability to hydroxyl radicals, phosphoric acid leaching rate and, finally, in-plane membrane conductivity. ABPBI membranes presented an excellent thermal stability, above 500 degrees C in oxygen, suitable mechanical properties for high phosphoric acid doping levels, a low methanol and ethanol limiting permeation currents, and oxygen permeability compared to Nafion membranes, and a low phosphoric acid leaching rate when exposed to water vapor. On the contrary, hydrogen permeation current was higher than that of Nafion, and the chemical stability was very limited. Membrane conductivity achieved 0.07 S cm(-1) after equilibration with a humid environment. Fuel cell tests showed reasonable good performances, with a maximum power peak of 170 mW cm(-2) for H-2/air at 170 degrees C operating under a humidified hydrogen stream, 39.9 mW cm(-2) for CH3OH/O-2 at 200 degrees C for a methanol/water weight ratio of 1: 2, and 31.5 mW cm(-2) for CH3CH2OH/O-2 at the same conditions than for methanol. (C) 2012 The Electrochemical Society. {[}DOI: 10.1149/2.014207jes] All rights reserved. (AU)

• Processo FAPESP: 10/07108-3 - Desenvolvimento de estratégias para aumentar a eficiência da reação de oxidação de etanol pelo mecanismo de 12 elétrons, dando CO2 como produto, no contexto das células a combustível de etanol direto
• Beneficiário: José Joaquín Linares León
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado