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

The selective oxidation of methane to value-added C 1 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 VO 4 ). The study found that isolated VO 4 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 VO 4 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. • A series of V/MSN catalysts were successfully prepared using organometallic grafting method. • The isolated VO 4 species are active sites for the selective oxidation of methane to formaldehyde and CO. • Oligomeric V-O-V species are active sites for deep oxidation of methane to generate CO 2 .