Thermal Unequilibrium of PdSn Intermetallic Nanocatalysts: From In Situ Tailored Synthesis to Unexpected Hydrogenation Selectivity
Minda Chen, Yu Yan, Mebatsion S. Gebre, Claudio Ordonez, Fudong Liu, Long Qi, Andrew Lamkins, Dapeng Jing, Kevin Dolge, Biying Zhang, Patrick M. Heintz, Daniel P. Shoemaker, Bin Wang, Wenyu Huang
Abstract
Abstract Effective control on chemoselectivity in the catalytic hydrogenation of C=O over C=C bonds is uncommon with Pd‐based catalysts because of the favored adsorption of C=C bonds on Pd surface. Here we report a unique orthorhombic PdSn intermetallic phase with unprecedented chemoselectivity toward C=O hydrogenation. We observed the formation and metastability of this PdSn phase in situ. During a natural cooling process, the PdSn nanoparticles readily revert to the favored Pd 3 Sn 2 phase. Instead, using a thermal quenching method, we prepared a pure‐phase PdSn nanocatalyst. PdSn shows an >96 % selectivity toward hydrogenating C=O bonds of various α,β‐unsaturated aldehydes, highest in reported Pd‐based catalysts. Further study suggests that efficient quenching prevents the reversion from PdSn‐ to Pd 3 Sn 2 ‐structured surface, the key to the desired catalytic performance. Density functional theory calculations and analysis of reaction kinetics provide an explanation for the observed high selectivity.