Control of the Cu ion species in Cu-SSZ-13 via the introduction of Co2+ co-cations to improve the NH3-SCR activity

Abstract

Cu-SSZ-13 has been successfully commercialized as a NOx removal catalyst for selective catalytic reduction with NH₃ (NH₃-SCR) in after-treatment systems. However, as global regulations on NOx emissions are becoming more stringent, the development of catalysts with higher NOx abatement ability is becoming more important. Herein, we propose a new strategy to enhance the reactivity of Cu-SSZ-13 by tuning the Cu ions in SSZ-13 zeolite. CuCo-SSZ-13 catalysts were synthesized by introducing Co²⁺ co-cations prior to loading Cu ions onto Cu-SSZ-13. The pre-loaded Co²⁺ co-cations induce the Cu ions to exist as more reactive species (Z–[Cu²⁺–OH⁻]) rather than less active species (2Z–Cu²⁺), which are classified by the number of adjacent framework Al atoms in SSZ-13. The designed CuCo-SSZ-13 catalysts demonstrate higher SCR reactivity than the conventional Cu-SSZ-13 catalyst under both low- and high-temperature conditions.