Enhanced metal-support interaction between Pd and hierarchical Nb2O5 via oxygen defects induction to promote CO oxidative coupling to dimethyl oxalate
2021
Production of ethylene glycol from coal is a particularly interesting route as it is an economic alternative of the petrochemical-based route. In this process, effectively generating dimethyl oxalate (DMO) is a crucial step by CO oxidative coupling reaction under Pd-based catalysts. However, the aggregation of Pd species over the support is still an issue that relates to deterioration of catalytic activity and stability. To this end, enhancing the metal-support interaction is urgently desired. In this work, hierarchical Nb2O5 (H-Nb2O5) microspheres with abundant oxygen defects were synthesized to anchor the Pd species thus promoting the electron transfer between Pd species and Nb species associated with the generation of interfacial Pd–NbOx sites. Besides, the thinned electron density of Pd species resulted from the electron-withdrawing of Nb species is beneficial to activate the adsorbed CO molecules, leading to a superior catalytic activity. The Pd/H-Nb2O5 catalyst exhibited 63.1% of CO conversion (theoretical maximum conversion: 64.3%) and 92.9% of DMO selectivity, with a DMO weight time yield of 1297.9 g·kgcat.-1·h-1, and remained robust even after 50 h of time on stream evaluation. Current work provides a deep insight into the CO activation mechanism and helps improve the catalytic stability by boosting interfacial electron interaction via oxygen defects induction, and also sheds light on the design and synthesis of high-performance catalysts in other heterogeneous catalysis fields.
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