Impact of support pore structure and morphology on catalyst performance of VOx/SBA-15 for selective methane oxidation

Abstract

The impact of SBA-15 support properties on the catalytic performance of final VOx/SBA-15 catalysts for the selective oxidation of methane toward formaldehyde was studied. Three different SBA-15 support samples were prepared by varying the ageing temperature (50, 70, 90°C; 24h each). Afterwards, vanadium oxide species were deposited by a generally known impregnation procedure. Catalytic tests were carried out in a fixed bed tubular reactor at 540–650°C, a feed molar ratio of CH4: O2=9: 1 and at a gas-hourly space velocity of 360,000L/(kgcat∙h). Among the three catalysts, the highest formaldehyde selectivity was obtained with the sample aged at 70°C. Characterizations carried out by nitrogen physisorption, XRD, UV–vis spectroscopy and SEM revealed that the ageing temperature has a considerable influence on pore diameters, surface areas as well as the particle morphology of SBA-15. It is suggested that pore geometry as well as particle morphology have a considerable influence on the generation of various vanadia species and thus, on the catalytic performance of VOx/SBA-15 catalysts.