First-Principles Periodic Density Functional Study of the Hydrogenation of Maleic Anhydride to Succinic Anhydride over Palladium(111)

Abstract

Gradient-corrected periodic density functional (DFT) calculations were carried out in order to examine the hydrogenation of maleic anhydride to succinic anhydride via a Horiuti-Polanyi like mechanism on the well-defined Pd(111) surface. Reaction path calculations were performed at a surface coverage of maleic anhydride corresponding to 0.11 monolayer. The hydrogenation of maleic anhydride to the maleic anhydryl surface intermediate was found to have the highest intrinsic barrier (+95 kJ/mol) on Pd(111), of all the elementary steps involved in the hydrogenation of the olefinic group of maleic anhydride. This step is endothermic by 17 kJ/mol. Calculations indicate that the second step in the mechanism, the hydrogenation of maleic anhydryl to succinic anhydride, has a slightly lower barrier (+89 kJ/mol) and is exothermic by 37 kJ/mol. In an effort to understand the effect of change in the electronic properties of the metal on the intrinsic barrier for maleic anhydride hydrogenation, the C−H bond formation re...