Reaction of Formic Acid on Zn-Modified Pd(111)

The decomposition of formic acid on Zn/Pd(111) was studied using Temperature Programmed Desorption and High Resolution Electron Energy Loss Spectroscopy. On Pd(111), HCOOH decomposes via both dehydration and dehydrogenation pathways to produce CO, CO₂, H₂ and H₂O. Small amounts of Zn (<0.1 mL) incorporated the Pd(111) surface were found to increase the stability of formate species and alter their decomposition selectivity to favor dehydrogenation, resulting in an increase in CO₂ production. This difference in reactivity appears to be caused by relatively long range electronic interactions between surface Pd and Zn atoms and may be important in Pd/ZnO methanol steam reforming catalysts which exhibit high selectivities to CO₂ and H₂.