Support composition engineering of gold catalysts for efficient oxidative esterification of ethylene glycol

To address the overcapacity in coal-to-ethylene glycol production, developing eco-friendly process to convert ethylene glycol into high-value-added chemicals is an important topic in current industrial research. In this work, we prepared a multi-component metal oxide-supported Au catalyst through a simple physical mixing and impregnation strategy, and investigated the influence of the support composition on the catalyst activity. Among all tested catalysts, Au/NbZnAlOx exhibited the optimal catalytic performance, achieving a selectivity of 94.6% for methyl glycolate, while maintaining good stability (>90% selectivity) after five cycles. The characterization of XRD, XPS, TPD and ATR-IR indicated that the incorporation of 10 wt% ZnO and 10 wt% Al2O3 into Nb2O5 effectively modulates the balanced distribution of acid-base sites on the catalyst surface and the substrate adsorption capacity. Meanwhile, NbZnAlOx support endowed Au nanoparticles highest electron density, promoting the activation of O2, thereby enhancing the catalytic activity. Kinetic studies revealed a remarkable reduction in activation energy from 77 kJ mol-1 to 24 kJ mol-1 upon ZnO/Al2O3 incorporation into Nb2O5. These findings provide insights into designing multi-component oxide-supported gold catalysts and highlight the critical importance of support composition in optimizing selective oxidation reactions.