Vanadium-containing SBA-15 systems prepared by direct synthesis: Physico-chemical and catalytic properties in the decomposition of dichloromethane

Vx-SBA-15 materials (vanadium content in the 0.7–4.8 wt.% range) were prepared by direct synthesis and tested in the catalytic decomposition of dichloromethane; a SBA-15 silica and a V/SBA-15 prepared by impregnation were used as reference samples. The structural and surface properties of all samples were characterized by means of complementary physico-chemical techniques. Vx-SBA-15 materials containing isolated vanadium sites were catalytically active towards dichloromethane conversion, with maximum conversion obtained by the catalyst having 2.2 wt.% vanadium. In Vx-SBA-15 materials prepared by direct synthesis, vanadium occurs mainly as isolated sites with tetrahedral coordination as far as its content does not reach the theoretical monolayer capacity (ca. 4 wt.%): unlike catalysts prepared by traditional impregnation method, oligomeric VOx species form only at high vanadium content.