Partial Oxidation of Methane on a Nickel Catalyst: Kinetic Monte-Carlo Simulation Study

TL;DR

This study uses kinetic Monte-Carlo simulations to analyze methane partial oxidation on nickel catalysts, revealing phase transitions, the effects of lattice coordination, diffusion, and impurities, and aligning well with experimental data.

Contribution

It introduces a detailed kinetic Monte-Carlo model for methane oxidation on nickel, exploring surface phenomena and phase transitions with new insights into catalyst behavior.

Findings

Higher lattice coordination widens reactive regions

Increased diffusion enhances maximum production rates

Impurities shift phase transition from abrupt to continuous

Abstract

Kinetic Monte-Carlo simulation is applied to study the partial oxidation of methane over a nickel catalyst. Based on the Langmuir-Hinshelwood mechanism, the kinetic behavior of this reaction is analyzed and the results are compared with previous experiments. This system exhibits kinetic phase transitions between reactive regions with sustained reaction and poisoned regions without reaction. The fractional coverages of the adsorbed species and the production rates of H2, CO, H2O, and CO2 are evaluated at steady state as functions of feed concentration of the methane and oxygen, and reaction temperature. The influence of lattice coordination number, diffusion, and impurities on the surface is investigated. The simulation results are in good agreement with the experimental studies where such results are available. It is observed that when the lattice coordination number is increased to eight, the width of the reactive region increases significantly. Moreover, the phase transition becomes continuous. The diffusion of adsorbed O and H on the surface plays a measurable role in the reaction, increasing the maximum production rates as the diffusion rate increases. In systems with impurities, the production rates are greatly reduced and the phase transition is also changed from being abrupt to continuous.