Unsaturated Penta-Coordinated Mo<sub>5c</sub><sup>5+</sup> Sites Enabled Low-Temperature Oxidation of C–H Bonds in Ethers
Qi Yang, Xiujuan Gao, Faen Song, Xiaoxing Wang, Tao Zhang, Pan Xiong, Yunxing Bai, Xingchen Liu, Xiaoyan Liu, Junfeng Zhang, Gang Fu, Yisheng Tan, Yizhuo Han, Qingde Zhang
Abstract
High Resolution Image Download MS PowerPoint Slide Selective oxidation of C–H bonds under mild conditions is one of the most important and challenging issues in utilization of energy-related molecules. Molybdenum oxide nanostructures containing Mo 5+ species are effective for these reactions, but the accurate identification of the structure of active Mo 5+ species and the catalytic mechanism remain unclear. Herein, unsaturated penta-coordinated Mo 5c 5+ with a high fraction in MoO x fabricated by the hydrothermal method were identified as the active sites for low-temperature oxidation of dimethyl ether (DME) by the deep correlation of characterizations, density functional theory calculations, and activity results, giving a methyl formate selectivity of 96.3% and DME conversion of 12.5% at unreported 110 °C. Low-temperature electron spin resonance (ESR) and quasi in situ X-ray photoelectron spectra (XPS) with the designed experiments confirm that the Mo 5c 5+ species can be formed in situ. Molybdenum located at the pentachronic site is preferable to significantly promote the oxidation of the C–H bond in CH 3 O* at lower temperatures.