Effect of calcination temperature on the structure and performance of molybdenum-tin catalyst for DME oxidation

The Mo1Sn2 catalysts with a Mo/Sn molar ratio of 1:2 were prepared by the hydrothermal method, and their structure was regulated by changing the calcination temperature (400–700 °C). The effect of the structural transformation of catalysts on the performance of selective oxidation of dimethyl ether (DME) to methyl formate (MF) was studied. It was found that the Mo1Sn2 catalyst calcined at 400 °C exhibited good performance in the oxidation of DME to methyl formate, showing a DME conversion of 9.2% and the MF selectivity of 86.9% at 110 °C and under atmospheric pressure without the generation of COx. The catalysts were systematically characterized by XRD, Raman, XPS, TPD, H2-TPR and in-situFT-IR. The results showed that the low-temperature calcination was favorable for the formation of MoOx structure and more Mo5+ species on the catalyst surface, resulting in the enhanced acidity and redox ability of the catalyst, and the increase of medium to strong basic sites on the catalysts. In such case, the activity and methyl formate production of the catalyst were significantly promoted.