Electrocatalytic oxidation of glycerol on Pt/C in anion-exchange membrane fuel cell: Cogeneration of electricity and valuable chemicals

Electrocatalytic oxidation of glycerol for cogenerating electricity and higher-valued chemicals on a Pt/C anode catalyst (2.4 nm) in an anion-exchange membrane fuel cell (AEMFC) was investigated. The peak power density of an anion-exchange membrane - direct glycerol fuel cell (AEM-DGFC) with 1.0 mg(Pt) cm(-2) anode and non-PGM catalyst cathode can reach 124.5 mW cm(-2) at 80 degrees C and 58.6 mW cm(-2) at 50 degrees C, while the highest selectivity of C-3 acids (glyceric acid + tartronic acid) can reach 91%. The study found that higher pH reaction media could enhance fuel cell output power density (electricity generation) and selectivity of C-3 acids, while lower glycerol concentration could improve the selectivity of deeper-oxidized products (mesoxalic acid and oxalic acid). The fuel cell reactor with the Pt/C anode catalyst demonstrated an excellent reusability, and successfully obtained tartronic acid with a selectivity of 50% and mesoxalic acid with a selectivity of 7%, which are high compared to heterogeneous catalytic glycerol oxidation in batch reactors. It is found that the anode overpotential can regulate the oxidation product distribution, and that higher anode overpotentials favor C-C bond breaking, thus lowering the C-3 acids selectivity. The reaction sequence of glycerol electro-oxidation detected in an electrolysis half cell with an on-line sample collection and off-line H PLC analysis agrees with the results obtained from single fuel cell tests. However, inconsistencies between the two systems still exist and are possibly due to different reaction environments, such as electrode structure, glycerol:catalyst ratio, and residence time of reactants. (C) 2012 Elsevier B.V. All rights reserved.