Highly Selective and Stable Isolated Non-Noble Metal Atom Catalysts for Selective Hydrogenation of Acetylene

A strategy to fabricate a stable and site-isolated Ni catalyst is reported. Specifically, Mo₃S₄ clusters allowed individual Ni atoms to bond with Mo and S to create a type of active site. A site-isolated Ni₁MoS/Al₂O₃ sample exhibited high performance in the selective hydrogenation of acetylene. Concretely, 90% ethylene selectivity was achievable at full acetylene conversion under relatively mild reaction conditions without any obvious decay in performance observed during longer testing periods. In contrast, a reference catalyst with Ni ensembles exhibited poor selectivity and stability. Density functional theory (DFT) calculations suggested that H₂ molecules were activated by a heterolytic route over Ni₁MoS/Al₂O₃, which enhanced the reaction rate. Improved selectivity originated from the unique isolated Ni^δ+ structure induced by Mo and S, which facilitated product desorption as opposed to overhydrogenation or oligomerization. This work provides a feasible way to construct site-isolated catalysts with higher active metal loadings and opens up an opportunity for selective hydrogenation.