Simulation of chemical reaction equilibria and kinetics in heterogeneous carbon micropores

Abstract

Abstract We present a simulation study which shows how the equilibrium yield and kinetics of chemical reactions can be enhanced by tailoring the structure and surface chemistry of the catalyst support material. Equilibrium results are presented for the ammonia synthesis reaction, N 2 +3H 2 ↔2NH 3 , occurring within various carbon supports, representing a range of chemical and physical surface heterogeneity. Using a simulation technique known as Reactive Monte Carlo (RxMC), we find that surface activation and pore width are primary factors in determining the conversion of the ammonia synthesis reaction while effects of surface corrugation are small. We probe the kinetic effects of physical confinement within microporous carbons by studying the bimolecular hydrogen iodide decomposition reaction, 2HI→H 2 +I 2 , in carbon slit-pores and nanotubes. The rate constant of this reaction is measured by combining the quasi-equilibrium hypothesis of transition-state theory (TST) with the RxMC simulation technique. The kinetic simulations represent a new method for probing reaction kinetics in non-ideal environments and show accurate results when applied to the hydrogen iodide decomposition reaction.