Oxidation of Hydrogen Off-gas from a Fuel Cell Using a Microstructured Reactor with Hydrophobic Pt-Al2O3 Catalyst Coating

Abstract

For polymer electrolyte fuel cells (PEFCs), a catalytic burner was proposed to convert a low energy hydrogen exhaust stream from PEFCs to water. Microreactors with Pt based catalyst coating showed their strength in safely handing the explosive mixtures of gaseous hydrogen and oxygen because dimensions of microchannel are smaller than quenching distance of hydrogen. However, the induction period was usually a long time for obtaining a high hydrogen conversion. Unfortunately, this induction time is difficult to be achieved for PEFCs because the hydrogen discharge is in pulse. To ignite the hydrogen oxidation at room temperature, a Pt-Al2O3 hydrophobic catalyst coating was firstly produced via grafting the support of alumina by 1H,1H,2H,2H-Tridecafluoro-n-octyltriethoxysilane (FAS). The Pt-Al2O3 hydrophobic catalyst showed significantly higher activity than that without hydrophobic modification. It was found that, for the catalyst of Pt-Al2O3, the support hydrophobicity prevented most of adsorbed water on the support which results in only a slight decrease in activity. The experimental results suggested that the Pt-Al2O3 hydrophobic catalyst coating is suitable for the oxidation of hydrogen for PEMFCs.