Origin of the different selectivity between Cu(111) and Pd(111) on methanol steam reforming reaction

Hydrogen production from methanol steam reforming (MSR) is attracting widespread attention in providing hydrogen for using fuel cells. Cu-based catalysts for MSR (CH3OH+H2O→CO2+H2) , nearly completely transform methanol to CO2 and H2, have different selectivity from catalysts, which transform methanol to CO and H2. Takezawa and Iwasa suggested that the different catalytic performances between Cu-based catalysts and Group VIII metals was attributed to the different reactivity of HCHO species formed in MSR. Although many reports suggested that the mechanisms of MSR on Cu-based catalysts was methanol decomposition followed by water gas shift reaction or methyl formate intermediates formed in MSR reacting with H2O to produce CO2 directly, the mechanisms are controversial now. The present work is focused on the mechanisms of MSR on Cu(111) and Pd(111) surfaces (one of Group VIII metals) by density functional calculations to investigate the origin of the different selectivity.