A Systematic Investigation into the Influence of Zeolite Framework Differences on the Catalytic Performance of Copper Sites in Ammonia Oxidation

The ammonia adsorption and desorption properties of copper-exchanged zeolites with distinct pore structures (i.e., Cu/BETA, Cu/ZSM-5, and Cu/SSZ-13) were systematically investigated under simulated engine conditions, focusing on their capacity for ammonia capture, release efficiency, and thermal stability. Among the tested catalysts, copper-exchanged SSZ-13 zeolite (Cu/SSZ-13) exhibited superior performance, attributed to its small-pore architecture, high surface area, and optimized copper ion distribution within the SSZ-13 framework. Notably, Cu/SSZ-13 demonstrated enhanced ammonia adsorption and desorption efficiencies compared to the large-pore Cu/BETA and medium-pore Cu/ZSM-5. Furthermore, Cu/SSZ-13 displayed exceptional thermal stability, a critical requirement for withstanding the fluctuating temperatures encountered in internal combustion engine operations. These findings suggest that the structural and chemical properties of the zeolite support, particularly in Cu/SSZ-13, play a decisive role in ammonia management. The study highlights the potential of Cu/SSZ-13 as an effective catalyst for mitigating ammonia emissions in engine exhaust systems, thereby supporting the adoption of ammonia as a cleaner alternative fuel. Future research will focus on optimizing catalyst formulations, evaluating long-term stability under realistic conditions, and integrating these materials into practical engine designs to maximize environmental benefits.