Mesoporous Nitrogen-Doped Carbon-Nanosphere-Supported Isolated Single-Atom Pd Catalyst for Highly Efficient Semihydrogenation of Acetylene.

Abstract

Semihydrogenation of acetylene in the ethylene feed is a vital step for the industrial production of polyethylene. Despite their favorable reaction activity and ethylene selectivity, the Pd-based intermetallic compound and single-atom alloy catalysts still suffer from the limitation of atomic utilization derived from the partial exposure of active Pd atoms. Herein, a hard-template Lewis acid doping strategy is reported that can overcome the inefficient utilization of Pd atoms. In this strategy, N-coordinated isolated single-atomic Pd sites are fully embedded on the inner walls of mesoporous nitrogen-doped carbon foam nanospheres (ISA-Pd/MPNC). This synthetic strategy has been proved to be applicable to prepare other ISA-M/MPNC (M = Pt and Cu) materials. This ISA-Pd/MPNC catalyst with both high specific surface area (633.8 m² g^-1 ) and remarkably thin pore wall (1-2 nm) exhibits higher activity than that of its nonmesoporous counterpart (ISA-Pd/non-MPNC) catalyst by a factor of 4. This work presents an efficient way to tailor and optimize the catalytic activity and selectivity by atomic-scale design and structural control.