Introduction to Microkinetics

Molecular catalysis has revealed that the macroscopic phenomena observed in experiments are caused by the emergent behavior of very small particles guided by the laws of quantum mechanics. Remarkably, these quantum effects are propagated over roughly ten orders of magnitude, at which point their behavior is considered to be classic.

Within this work, we will elaborate on the connection between the smallest quantum scale and the larger macroscopic scale, providing a theoretical framework on which many kinetic studies in heterogeneous catalysis are based. We will focus on the underlying quantum chemical mechanism leading to the observed overall rate laws in chemistry and process engineering.

ISBN: 978-90-386-4520-9

Quantum Chemical and Microkinetic Modeling of the Fischer-Tropsch Reaction

In this dissertation, the kinetics and mechanism of the Fischer-Tropsch reaction are investigated. The Fischer-Tropsch reaction is a very complex reaction involving many elementary reaction steps. The rate of these steps depends in a sensitive manner on the type of transition metal, the surface metal atom topology and the composition of the adsorbed layer. While density functional theory methods provide accurate data for the rate constants for these elementary reaction steps, microkinetics simulations allow to predict the compositon of the adsorbed layer on the surface as well as the rates of all elementary reaction steps. In this manner, important issues can be resolved that pertain to the mechanism of the ­Fischer-Tropsch reaction such as the dominant reaction pathway from reactants (CO and H2) to products (alkanes, alkenes, oxygenates and water). Pertinent questions relevant to the Fischer-Tropsch reaction treated in this thesis are as follows. What is the manner of CO dissociation? Which of the two main proposed mechanisms for chain growth - the carbide mechanism or the CO insertion mechanism - dominates? What are the rate-controlling steps and which elementary reaction steps influence the product selectivity?

ISBN: 978-90-386-3793-8