Reaction pathways of methane abatement in Pd-Rh three-way catalyst in heavy duty applications: A combined approach based on exhaust analysis, model gas reactor and DRIFTS measurements

Methane abatement pathways in Pd/Rh three-way catalysts have been investigated three scales ranging from a vehicle application size catalyst, model gas reactor and the catalyst powder form. A special test rig was designed for investigation of catalysts, allowing sampling along at discrete spatial locations, which are subject to different feed compositions. Dependent on history chemical environment significant differences methane conversion rate identical identified. At steady state low reaction pathway identified as limited only direct oxidation by oxygen. Following rich-to-lean transition, exhibited more than 8 times higher rates compared state. The high attributed activation steam reforming (SR) related transient reduction ceria. SR efficiency decreased with time finally converged levels. findings were validated using enabling analysis under well-defined deactivation further analyzed infrared spectroscopy (DRIFTS). Evidences DRIFTS measurements showed that linked formation carbonaceous species surface, most likely carbonates. coherent results engine exhaust analysis, study give important insights pathways. this suggest formulation operation strategies should focus stimulation maintenance activity towards through targeted periodic lean/rich transitions.