Cu/Fe-UZM-35 Catalysts for NOx Abatement in Diesel Vehicles for Next-Stage Emission Standards

Cu-based zeolite catalysts face the challenge of high N2O emissions, while Fe-based zeolite ones suffer from insufficient low-temperature activity and hydrothermal stability. To combat these issues, we developed Cu-Fe-coupled UZM-35 zeolite catalysts with NOx conversion over 85% in the temperature range of 175 °C. Meanwhile, over 80% of NOx can be converted between 150 and 550 °C. Furthermore, over 95% of N2 selectivity was obtained in the whole temperature range. Over these catalysts, Cu and Fe species were uniformly dispersed, being mostly in ionic forms; their presence hardly changed the framework and pore structure of the zeolite. Moreover, the Cu-Fe bimetallic zeolite contained abundant acid sites and even more active species, which ensured its superior catalytic performance for NOx reduction. In addition, the coupling of Cu and Fe stabilized both framework and active sites; therefore, superior hydrothermal stability was obtained. This study provides valuable insights for the development of SCR catalysts for diesel vehicles aimed at meeting future emission standards.