High-Durability Metal-Doped Cu/ZnO/Al2O3 Catalysts for Reforming of Model Biomethanol.

A series of metal-doped Cu/ZnO/Al2O3 catalysts (M-CZA; M = Co, Ni, Ru, Rh, Pd, Pt) were synthesized and evaluated for the autothermal reforming (ATR) of model biomass-derived methanol (biomethanol) containing trace ethanol or 1-butanol impurities. The objective was to improve the efficient utilization of impure biomethanol for hydrogen production. The introduction of 1 mol% ethanol decreased the methanol conversion and hydrogen production rates over CZA, Co-CZA, Pd-CZA, and Pt-CZA catalysts during the initial reaction stage, with further decline over time. In contrast, Ni-CZA, Ru-CZA, and Rh-CZA maintained stable activity under identical conditions. Ethanol was converted mainly into C1-C3 byproducts such as methane, acetaldehyde, and methyl acetate on CZA, Co-CZA, Pd-CZA, and Pt-CZA, whereas Ni-CZA, Ru-CZA, and Rh-CZA predominantly formed methane and carbon monoxide with negligible formation of carbonaceous species. Temperature-programmed oxidation indicated the deposition of carbonaceous species on spent CZA, Co-CZA, Pd-CZA, and Pt-CZA, but not on Ni-, Ru-, or Rh-modified catalysts. These results suggest that Ni, Ru, and Rh enhance C-C bond cleavage in lower alcohols, thereby suppressing carbon deposition and improving catalyst durability. This study provides practical insights for designing efficient ATR catalysts for on-site hydrogen generation from biomethanol containing impurities.