Modeling surface kinetics with first-principles-based molecular simulation

Abstract

A first-principles-based dynamic Monte Carlo (MC) algorithm was developed to simulate catalytic kinetics on well-defined transition metal surface. Density functional quantum chemical calculations along with fundamental experimental data were used to establish an intrinsic kinetic database. Both pairwise and bond order conservation models were parameterized from this database and used internally in the MC simulation to describe adsorbate lateral interactions. The MC algorithm is an object-oriented simulation that tracks the dynamic changes in the atomic surface structure with changes in processing conditions by following the molecular kinetics. The MC algorithm is applied herein to two relevant catalytic systems: (1) nitric oxide decomposition on Rh (1 0 0) and (2)ethylene hydrogenation over Pd (1 0 0 ). The results indicate that the ab initio modified bond order conservation model provides reliable predictions of surface kinetics. The simulated temperature programmed desorption profiles agree with the experimental measurements for both NO and ethylene. The simulated overall activation energy for the kinetics of ethylene hydrogenation was 9.2 kcal/mol that compares very well with experimental estimates of 6.5–10.7 kcal/mol.