Studies On Selective CO Oxidation From Methanol Reforming Hydrogen Source

Hydrogen production from methanol reforming is one of the most promising approach for proton exchange membrane fuel cells (PEMFCs). Due to the strong chemisorption on the anode PtRu catalyst surface, trace CO will dramatically depress the performance of PEMFC. It is very essential to clean up CO from methanol reformate for PEMFC applications. Research showed that selective CO oxidation is the most effective and economic method to reduce CO down to 50 ppm level, which can be tolerated by the PtRu catalyst.This paper prepared monolithic honeycomb catalysts which could selectively oxidize CO down to 50 ppm level from methanol reformate. The catalysts with Pt, Pd, Ru, Rh supported on Al₂O₃ were studied and Pt was the best. Further investigation showed that doping Co in Pt/Al₂O₃ could improve CO conversion and selectivity, broaden its reaction temperature window and shift it down to low temperature.Effects of various operation parameters on selective CO oxidation was systematically studied over Pt/Al₂O₃ catalyst, including temperature, molar ratio of O2 to CO, H₂O, CO₂, space velocity, CO concentration, H₂ concentration and hysteresis phenomena. Effects of side reactions, including H₂ oxidation, CO reverse water-gas-shift reaction (rWGS) and methanation, were also investigated. Then the optimal operation conditions were obtained.The reaction mechanism of selective CO oxidation over Pt/Al₂O₃ was launched. All parameters in the kinetic models, which described CO oxidation and H₂ oxidation, were obtained.