A Kinetic Study of Hydrocarbons Reactivity on Palladium Catalysts through a DFT Approach

Abstract

ABSTRACTPalladium clusters have been chosen to represent a typical supported heterogeneous catalyst and their interaction with hydrocarbons has been investigated theoretically. The calculations were performed through density functional theory and the Becke-Lee-Yang-Parr hybrid (B3LYP) functional was adopted to calculate exchange and correlation energy. An effective core potential basis set (ECP on core electrons and Dunning/Huzinaga on outer electrons) was found sufficiently accurate to reproduce experimental data. Clusters containing up to seven Pd atoms were considered and their interaction with hydrogen, methane and ethane and their fragments was analyzed and a kinetic study of the system was performed. Transition states structures and energies were calculated through quantum mechanics and kinetic constants were derived from a statistic thermodynamic approach. On the basis of such information, a kinetic model that accounts for ethane transformations. Finally the kinetic scheme was embedded in a plug flow reactor model and simulations were performed to test the validity of the developed mechanism. In this way information obtained at the atomic scale were adopted to study phenomena occurring on the much higher reactor scale.