Amino Nests Boost Pd/SiO₂ Single-Atom Catalysts for Efficient Selective Semi-Hydrogenation of Acetylene

The selective hydrogenation of acetylene to ethylene is a critical industrial process for purifying ethylene feedstocks. Palladium single-atom catalysts (Pd SACs) exhibit exceptional ethylene selectivity in this hydrogenation reaction. However, their isolated active sites show limited ability to capture and adsorb trace acetylene molecules from ethylene-rich streams, resulting in relatively low hydrogenation activity. To overcome this limitation, we designed Pd single-atom catalyst on the SiO₂ surface modified with amino nests (Pd₁/SiO₂-NH₂). In this architecture, Pd single atoms are embedded within amino nests on the surface of SiO₂-NH₂ support. Combined experimental and density functional theory (DFT) calculations reveal that amino nests selectively capture and adsorb acetylene molecules from ethylene-rich streams, facilitating the key acetylene adsorption step. The Pd─N bonds formed between the amino nest and the Pd atom promote hydrogen activation. At 190 °C, the Pd₁/SiO₂-NH₂ catalyst achieves complete acetylene conversion with the ethylene selectivity of 92%. Remarkably, it delivers a specific activity of 1900.36 mol _C2H2 ^-1 mol_Pd ^-1 min^-1, surpassing all previously reported SACs. This work establishes an amino nest-assisted design paradigm for single-atom catalysts, enabling efficient, selective semi-hydrogenation of acetylene.