Activity Trends of Methane Oxidation Catalysts under Emission Conditions

The emission of unburned exhaust methane from natural-gas-based combustion engines is an important source of greenhouse gas to control. Rutile IrO 2 has shown great potential as a methane oxidation catalyst, but further developments for practical use have been slow as the kinetic mechanism and design principles under exhaust conditions are poorly understood. Here, we demonstrate the experiment-validated first-principles-based microkinetic model (MKM) for IrO 2 to elucidate the mechanistic insights and develop the descriptor-based MKM screening pipeline to discover feasible catalysts for methane complete oxidation. The framework uses a minimal number of ab initio descriptors suggested by sensitivity analysis and scaling relations, equipped further with a machine learning model to extend the search space to a larger scale. We search through hundreds of doped rutile oxides by constructing t…