Density functional study of methoxide decomposition on PdZn(100)

Abstract

Reactants, products and transition state species involved in the decomposition of methoxide, CH₃O to CH₂O + H and CH₃ + O fragments on the PdZn(100) surface have been studied theoretically. We used periodic slab models and a density functional method and compared our results to those for the corresponding complexes on the more compact PdZn(111) surface investigated earlier. On PdZn(100), both C–H and C–O bond scission reactions of CH₃O were found to be somewhat more endothermic than on the (111) surface. Transition state structures for both cleavage reactions are similar to their PdZn(111) analogues. Similarly to PdZn(111), C–H bond scission of methoxide is kinetically favored on PdZn(100) over C–O bond breaking. However, even the activation barrier for C–H bond breaking on PdZn(100) surface is rather high. Thus, defects most probably are responsible for methoxide decomposition on PdZn catalysts.