Decoupling Active Sites Enables Low-Temperature Semihydrogenation of Acetylene

Achieving high ethylene selectivity while preserving high reactivity for semihydrogenation of acetylene over Pd-based catalysts is still challenging. Here, we propose a structure of encapsulated Pd nanoparticles to enhance catalytic performance via a low-dose doping-segregation strategy using Pd-doped SrTiO₃ as a precursor. The encapsulated Pd nanoclusters are revealed to be protected by a thin TiO_x shell to prevent contact with acetylene/ethylene. However, hydrogen can still be efficiently activated on the encapsulated Pd sites and react with the adsorbed acetylene on surface Ti³⁺ sites via hydrogen spillover. By taking advantage of weaker ethylene adsorption on partially reduced oxide TiO_x, this catalyst shows an enhanced performance of 98% conversion and 92% selectivity with a specific activity of 5552 mol_C2H2·mol_Pd^–1·h^–1 at 100 °C, significantly surpassing most Pd-based catalysts. This strategy decouples active sites for the activation of different reactants, providing a thought for the development of highly active and selective hydrogenation catalysts.