Nanostructured Porous Three-Way Catalyst Particles via Two-Fluid Nozzle Spray Drying with a Binder-Controlled Structure for an Exhaust Gas Purification System

The increasing hybridization of automobiles is driving demand for further miniaturization of exhaust gas purification systems. To improve the utilization efficiency of three-way catalysts (TWCs), aggregated TWC particles deposited onto porous ceramic substrates have been proposed as an effective catalyst structuring strategy. Although the introduction of macroporosity into aggregated TWC particles can enhance internal mass transfer, conventional ultrasonic nebulization-based aerosol methods suffer from low productivity and limited control over particle size. Herein, a scalable fabrication strategy for porous TWC particles using a two-fluid nozzle spray drying process is demonstrated, utilizing TWC nanoparticles (∼9.8 nm) and PMMA template particles (∼400 nm). The influence of binder concentration on particle formation, pore structure, and catalytic performance is investigated. Polymer-template-assisted spray drying enabled the formation of spherical porous TWC particles with tunable particle size and macroporosity suitable for practical catalyst deposition. The binder was found to promote particle spheronization while influencing pore characteristics and catalytic accessibility, and an optimal binder concentration of 5 wt % was identified to balance particle morphology and CO oxidation performance. In addition, increasing PMMA template concentration enhanced macroporosity, improving gas accessibility and lowering the light-off temperature for CO oxidation. This study establishes fundamental design principles linking binder content, macroporous architecture, and catalytic performance under scalable processing conditions, providing a practical pathway for producing structurally optimized porous TWC particles for advanced exhaust aftertreatment applications.