CO Oxidation Enabled by Three-Way Catalysts Comprising Pd/Rh Nanoparticles Supported on Al₂O₃ and CeZrO₄ Confined in Macroporous Polystyrene Latex Templates

Over the past decade, the three-way catalyst (TWC) has become a critical technology for reducing pollutant emissions from gasoline-powered vehicles. Due to the global rise in the number of vehicles and limited resources, it is necessary to operate a TWC at high space velocities (SVs) to minimize the usage of expensive metals and reduce catalyst consumption. However, the mass transfer limitation within the nanostructure of TWC particles hinders the full utilization of their active surfaces, limiting their performance, particularly at high SVs. To address this challenge, our study focused on the development of particles derived from TWC nanoparticles with a hierarchically ordered macroporous structure via a template (polymer–particle)-assisted spray method, followed by a reheating process. Spherical catalyst particles with a macropore size of approximately 150 nm and a specific surface area of 79.9 m 2 g –1 were successfully synthesized by optimizing the reheating conditions (i.e., temperature and time). The catalytic evaluation of the model reaction (CO oxidation) revealed that the TWC particles with the macroporous structure exhibited better catalytic performance than those without the structure (i.e., aggregate structures and nanoparticles). This improvement can be attributed to the enhancement of the mass transfer efficiency induced by the macropores. Our findings provide valuable insights for developing efficient material structures for future catalysts.