Structure sensitivity of alcohol reactions on (110) and (111) palladium surfaces

A temperature programmed reaction/desorption (TPD) study of decomposition pathways of methanol, ethanol, 1-propanol and 2-propanol was conducted on the clean Pd(110) surface under ultra-high vacuum conditions. No alcohol underwent C-O scission. Alcohols appear to react on this clean surface via the same dehydrogenation and decarbonylation steps observed on the Pd(111) surface. In contrast to previous reports noting substantial differences in methanol chemistry on the Pt(110) and (111) surfaces, the reactions of methanol and ethanol were found to be the same on the Pd(110) and (111) surfaces, giving rise to H₂ plus CO from methanol, and H₂, CO, and CH₄ from ethanol. The C₃ alcohols, 1- and 2-propanol, did produce somewhat different products on the Pd(110) and (111) surfaces, but these differences can be accounted for by differences in the chemistry of intermediate reaction products, rather than different reaction pathways of the parent alcohols.