Nickel Nanoparticles Encapsulated in SSZ-13 Cage for Highly Efficient CO₂ Hydrogenation

CO2 catalytic hydrogenation to energy-rich chemical feedstocks using renewable hydrogen provides an attractive avenue for the climate-change issues and global energy demands. However, the rational design of catalysts with high activity, selectivity, and stability toward CO2 hydrogenation remains exceptionally challenging. Here, we report Ni/SSZ-13 catalyst that captures the design concept of metal nanoparticle encapsulation in a cage of porous materials. The results indicate that nickel species mainly exist in the form of Ni metal on the SSZ-13 support and serve as the active phase for CO2 hydrogenation. The stronger interaction between metallic nickel and the SSZ-13 support is responsible for the stability of nickel nanoparticles. 15%Ni/SSZ-13 catalyst exhibits 72% CO2 conversion and 96% CH4 selectivity at 450 degrees C. The relatively higher CO selectivity of Ni/SSZ-13 catalyst at the higher temperatures is associated with the reverse water-gas shift reaction due to its endothermic nature. There is no obvious catalyst deactivation during the long-term hydrogenation experiments. The encapsulation effect of nickel nanoparticles in the well-ordered SSZ-13 cage is responsible for the high antisintering ability and thermal stability of Ni/SSZ-13 catalyst. Quantum chemistry calculation was also conducted to reveal the microcosmic reaction mechanism of CO2 hydrogenation. The nickel-zeolite interface is found to be the active center of Ni/SSZ-13 catalyst. CO2 hydrogenation over Ni/SSZ-13 catalyst is mainly controlled by the direct C-O bond scission pathway. This study marks a step ahead toward CO2 hydrogenation to value-added fuels and reveals the encapsulation effects of metallic nanoparticles that will spark inspiration for other industrial applications.