Tolerance of Impurities in Bio-Ethanol on Pd/C Catalyst Toward the Ethanol Oxidation Reaction in Alkaline Media

In the recent years, bio-ethanol could be produced massively from various sources and has attracted great interests as an alternative fuel source in low temperature fuel cells.  However, the bio-ethanol may contain some impurities, such as lactic acid, acetic acid, glucose, glycerol, maltose, fructose and so on, to contaminate the catalysts in the fuel cells. The objective of this work is to investigate the effects of impurities in bio-ethanol on the performance of Pd/C catalyst for the ethanol electro-oxidation reaction (EOR) in alkaline media.

The electrocatalytic activities of Pd/C toward EOR with the addition of 0.01 M of various organic compounds were tested by cyclic voltammetry (CV). By comparing the EOR current at the corresponding potential, the presence of lactic acid and acetic acid was found to have little effects on the electrocatalytic activity of Pd/C toward EOR; however, the performance of Pd/C toward EOR get worse with the presence of glucose, glycerol, maltose, and fructose.

The quasi-steady state current for EOR on the Pd/C catalyst was also measured by chronoamperometry (CA) measurements. The EOR current of the Pd/C decayed slowly with time. The steady currents at 0.5 V for EOR on Pd/C catalyst exhibit the order of EOR » EOR+0.01 M lactic acid > EOR+0.01 M acetic acid > EOR+0.01 M glucose > EOR+0.01 M glycerol > EOR+0.01 M maltose » EOR+0.01 M fructose. This trend is consistent with the CV test results.

The tolerance of impurities in bio-ethanol on other catalysts toward the ethanol oxidation reaction in alkaline media will be also studied and discussed.