Multiscale Modelling in Computational Heterogeneous Catalysis - Multiscale Molecular Methods in Applied Chemistry - page 69

Multiscale Modelling in Computational
Heterogeneous Catalysis

F.J. Keil

Abstract The goal of multiscale modelling of heterogeneous catalytic reactors is
the prediction of all steps, starting from the reaction mechanism at the active centre,
the rates of reaction, adsorption and diffusion processes inside the porous system
of the catalyst support, based on first principles, quantum chemistry, force field
simulations and macroscopic differential equations. The progress in these fields of
research will be presented, including linking models between the various levels of
description. Alkylation of benzene will be used as an example to demonstrate the
various approaches from the active centre to the reactor.

Keywords Computational heterogeneous catalysis Molecular dynamics Monte

Carlo Multiscale modelling Quantum chemistry

Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
2 Computational Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.1 Quantum Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.2 Monte Carlo, Molecular Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
2.3 QM/MM, Transition State Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3 Applications: From the Active Centre to the Chemical Reactor . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
4 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

1 Introduction

Catalysis is the study of materials that can accelerate reactions and control reaction
mechanisms. After a catalytic cycle, namely adsorption of reactants, reactions and
desorption of products, the catalyst is restored to its initial state. An ideal catalyst