High-Performance and Stable Three-Way Catalyst Achieved via Ultrasonic Treatment for Gasoline Vehicle Emission Control

Three-way catalysts (TWCs) containing significant amounts of precious metals are commonly employed to purify exhaust emissions (CO, NOx, and THC) from gasoline-powered vehicles. A critical factor contributing to TWC degradation is the sintering of these precious metals. Maintaining the appropriate particle size and distribution of the metals is essential for optimal catalyst performance. In this study, palladium (Pd) nanoparticles with a uniform size were synthesized using ethylene glycol as a reductant under ultrasonic conditions, yielding particles in the range of 3 nm to 5 nm. These Pd nanoparticles were subsequently used to prepare three-way catalysts on cordierite substrates supplied by Corning (China) Inc. Chemisorption analysis revealed that the Pd active component in the catalysts prepared via the ultrasonic method exhibited higher dispersion than the state-of-the-art commercial catalysts. The aged catalysts were obtained after 150 hours of aging following the General Motors’ Aged Cycle mode at an inlet temperature of 875 °C (GMAC-875). Performance evaluation results indicated that the catalyst prepared through ultrasonic reduction after aging demonstrated superior performance compared to commercial catalysts, as shown in light-off evaluation with the Mitsubishi 4G69S4N gasoline engine and vehicle emission tests (WLTC) using a Lavida test vehicle.