Microkinetic Modeling of Support Effects in PdO-Based Methane Oxidation Catalysts

The impact of different support materials on the catalytic activity of PdO-based catalysts during methane oxidation is studied using microkinetic modeling. Two independent sets of microkinetic data were developed, numerically studied, and validated with experimental data obtained in dry and various humid reaction gas mixtures. An automated optimization routine refined the original physics-based mechanism, resulting in a set of thermodynamically consistent kinetic parameters for PdO/SnO$_2$ and PdO/ZrO$_2$ that accurately describe the catalytic measurements. The findings indicate that SnO$_2$ and ZrO$_2$ supports enhance catalytic activity and methane conversion, even in the presence of water. Despite potential inhibition from hydroxyl formation on the catalyst surface, the results of the kinetic models show a significant influence of the support materials on the reactions occurring on the PdO surface. Sensitivity analyses of the refined mechanisms identify essential kinetic parameters and reaction pathways of the developed mechanisms under dry and humid conditions. Overall, this study illustrates the effectiveness of the automated optimization approach in accelerating kinetic model development and incorporating reaction engineering over different supports, which may be exploited for scale-up processes.