Photo-triggered catalytic reforming of methanol over gold-Promoted, copper-Zinc catalyst at low ignition temperature

Abstract

Lowering the ignition temperature in partial oxidation of methanol (POM), an exothermic reaction, is important for further application in hydrogen fuel cell development. This study has clearly revealed that photo-triggered catalytic partial oxidation of methanol (photo-POM) over gold-promoted copper-zinc catalyst decreased ignition temperature in response to 2–10% increments of gold content. In particular, A10CZ (Au/Cu/ZnO catalyst with 10% Au, 30% Cu, 60% Zn) effectively reduced the ignition temperature (Ti) to room temperature and maintained 95% SH2 (hydrogen selectivity) methanol–oxygen mixtures (volume 2:1) under 200W UV light with a wavelength of 377nm. During the ignition period, methoxy groups (–OCH3) were adsorbed onto the A4CZ surface, and then transferred to the intermediate formate state. The photo-generated electrons from ZnO were easily trapped by electronic acceptors, such as copper and gold, which was confirmed by in-situ X-ray absorption near-edge structure (XANES) spectra during photo-POM reaction. Gold also promotes the absorption of near UV light and significantly enhances the charge separation by extracting electrons from photo-excited ZnO, which consequently improves the photocatalytic activity at lower ignition temperature.