München 2006 – wissenschaftliches Programm

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AKE: Energie

AKE 2: Brennstoffzellen

AKE 2.3: Vortrag

Montag, 20. März 2006, 15:25–15:45, L

Study of ethanol and ethylene glycol by Fuel Cell Differential Electrochemical Mass Spectrometry(FC-DEMS) — •Vineet Rao¹, Carsten Cremers², and Ulrich Stimming¹ — ¹Department of Physics E19, TU Munich, James-Franck-Str. 1, D-85748 Garching — ²ZAE Bayern, Walther-Meißner-Str. 6, D-85748 Garching

The ethanol and ethylene glycol electro oxidation at gas diffusion electrodes (GDE) made of different catalysts, Pt/C, PtRu/C and PtSn/C, were both studied by on-line differential electrochemical mass spectrometry (DEMS) in a wide temperature range (30-90 ^∘C) as function of the anode potential, the fuel concentration and catalyst loading. CO₂ was observed as doubly ionised carbon dioxide molecular ion at m/z = 22, and acetaldehyde was observed as CHO⁺ fragment at m/z = 29. The CO₂ current efficiency (CCE) for ethanol oxidation reaction (EOR) shows a strong dependence on the anode potential, decreasing rapidly with increasing potentials >0.5V RHE. But the CCE for ethylene glycol oxidation reaction (EGOR) is almost potential independent. The CCE for the EGOR goes down with increase in concentration of ethanol. CCE for both reactions shows a strong dependence on the catalyst layer thickness or catalyst loading, respectively. It increases with increasing catalyst loading. The formation of CO₂ in both reactions is a temperature-activated process with apparent activation energy of 21 kJ/mol. The apparent activation energy for ethanol oxidation is estimated to be 31kJ/mol while 25kJ/mol for ethylene glycol oxidation.