  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.
