Preparation and characterization of P–Mo–V mixed oxide-incorporating mesoporous silica catalysts for selective oxidation of methane to formaldehyde Original Research Article

P–Mo–V mixed oxide-incorporating mesoporous silica catalysts with different contents were prepared by a template method with Keggin-type heteropoly acid (HPA), H5PMo10V2O40, under acidic conditions, followed by calcination at 873 K for 5 h. During the preparation, the HPA used as a precursor of the oxide acted as a co-acid of HCl that controlled the acidity of the starting mixture. The catalysts were characterized by thermal analysis, X-ray diffraction, X-ray fluorescence spectroscopy, N2 adsorption, transmission electron microscopy, and Raman spectroscopy. The results indicated that the framework of P–Mo–V incorporated mesoporous silicas was similar to that of MCM-48. The molar ratio of P:Mo:V (1:10:2) in the catalysts showed no significant change from the HPA precursor and the mixed oxides were highly dispersed below 6.68 wt% content. The catalysts showed good activity in the selective oxidation of methane to formaldehyde with oxygen.