Pd catalysts doped with B/C atoms in the subsurface: the positive effect of interstitial atoms in regulating the selectivity of acetylene catalytic hydrogenation.

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At present, the modification of palladium (Pd) catalysts is an important topic due to its potential to enhance catalytic performance and reduce catalyst costs. In this work, boron (B) and carbon (C) are interstitially doped into the subsurface of Pd to construct Pd4LB2L and Pd4LC2L catalysts. The adsorption properties of acetylene and ethylene, the mechanism of acetylene hydrogenation, and ethylene selectivity are studied based on density functional theory (DFT) calculations. The results show that the ethylene selectivity of the Pd4LB2L catalyst is significantly enhanced compared with that of Pd(111). The adsorption of CH2CH2 is weakened substantially after B element doping, and the ethylene selectivity descriptor (Esel) value of the Pd4LB2L catalyst reaches 19.7 kJ mol-1. It is revealed that non-metallic atoms doped into the subsurface layer of metal catalysts change the adsorption of reactant/intermediate molecules and the selectivity of ethylene by affecting the electronic structure and properties of Pd atoms in the surface layer. This work provides insights into the selectivity of modified Pd-based catalysts for selective hydrogenation of acetylene and realization of cost-effective catalysts.