Constructing an efficient NiCu single-atom alloy towards acetylene semi-hydrogenation

Abstract

Acetylene semi-hydrogenation is a critical industrial process for purifying raw steam used in polyethylene production. Nickel-based particles have emerged as promising non-noble catalysts for this application. Designing a catalyst with high activity and ethylene selectivity has long been a goal in this field. Single-atom alloys (SAAs) with integrated functions are potential candidates for achieving the two goals simultaneously. Here, we reported a new strategy to construct efficient NiCu SAAs, uncovering two factors for the density of catalytic Ni sites, the alloying degree and exposure degree of Ni. Increasing the reduction temperature could enhance the alloying degree of Ni atoms, and it could also enlarge the particle size of the NiCu SAAs and result in decreased exposure of Ni atoms. The two opposing factors simultaneously led to a volcano-shaped dependence of reaction activity on the reduction temperature. The optimal NiCu single-atom alloys, balancing both key factors, demonstrated notable specific activity and selectivity (29 582 mL_C2H2 min⁻¹ g_Ni⁻¹ and 92.7% ethylene selectivity under 100% acetylene conversion). This research introduced a new strategy for synthesizing efficient SAAs for selective hydrogenation through a straightforward approach.