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

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.

Graphical abstractP–Mo–V mixed oxide-incorporating mesoporous silica catalysts were prepared by using heteropoly acid, H5PMo10V2O40, as a precursor of the oxides and as a co-acid to control the content of the active species and the porous property of mesoporous silica. The catalysts with highly dispersed active species showed good selectivity and yield of HCHO in methane selective oxidation reaction. Figure optionsDownload full-size imageDownload as PowerPoint slide