Increasing the Distance of Adjacent Palladium Atoms for Configuration Matching in Selective Hydrogenation

Precisely tailoring the distance between adjacent metal sites to match adsorption configurations of key species for the targeted reaction pathway is a great challenge in heterogeneous catalysis. Here, we report a proof-of-concept study on the atomically sites-tailored pathway in Pd-catalyzed acetylene hydrogenation, i.e., increasing the distance of adjacent Pd atoms (d(Pd-a-Pd)) for configuration matching in acetylene semi-hydrogenation against coupling. d(Pd-a-Pd) is identified as a structural descriptor for describing the competitiveness for reaction pathways, and the increased d(Pd-a-Pd) prefers the semi-hydrogenation pathway due to simultaneously promoted C2H4 desorption and the destabilized transition state of the C2H3* coupling. Spectroscopic, kinetics and electronic structure studies reveal that increasing d(Pd-a-Pd) to 3.31 angstrom delivers superior selectivity and stability due to energy matching and appropriate hybridization of Pd 4d with In 2s and, especially, 2p orbitals.

Automated summary

The study reports a method to prepare atomically sites in a catalyst and investigates the influence of the distance between adjacent metal sites on the reaction pathway. The increased distance between adjacent Pd atoms is found to enhance the selectivity and stability due to energy matching and appropriate hybridization.