Selective oxidation of methane to formaldehyde and carbon monoxide over V/MSN catalysts with isolated VO4 sites

Abstract

The selective oxidation of methane to value-added C₁ chemicals (e.g., HCHO and CO) is a crucial process in the chemical industry. Recent studies indicate that the generation of highly dispersed isolated active sites is crucial for improving the performance in the selective oxidation of methane and studying the corresponding structure–activity relationship. Therefore, we used mesoporous silica nanoparticles (MSN) as supports and utilized grafting method to prepare catalysts with more selective oxidation active centers (isolated VO₄). The study found that isolated VO₄ centers are the active sites for the selective oxidation of methane to formaldehyde, and CO is the product of further oxidation of formaldehyde. The total selectivity of formaldehyde and CO on all catalysts is higher than 83.6 %. Among them, the highly dispersed and isolated VO₄ tetrahedral active centers on the 2 V/MSN catalyst could stably convert methane to formaldehyde, achieving the highest formaldehyde yield of 3.7 % at 670 °C.