Characterization and performance of V 2O 5–TiO 2 catalysts prepared by rapid combustion method

Abstract

The VO x –TiO 2 (VT) catalysts were prepared by the rapid combustion (RC) method and characterized by SEM, XRD, Raman, XPS, NH 3-TPD and H 2-TPR techniques. The catalytic performance was evaluated in the methanol oxidation reaction. The SEM result showed that the VT catalysts were consisted of nanoparticle with mean grain size about 30 nm. The RC process enhanced the formation of Ti (1− x) V x O 2. The XRD and Raman results revealed that the vanadia transformed from the isolated VO x to polymeric VO x and then as crystalline V 2O 5 on the surface of V x Ti (1− x) O 2. The polymeric VO x was predominant when V 2O 5 content was 30 wt.%. The H 2-TPR and NH 3-TPD results showed that the polymeric VO x exhibited more acidic sites and stronger reducibility than isolated VO x and crystalline V 2O 5. The catalytic activity result showed that the polymeric VO x was more active in methanol oxidation. The product distribution showed that the VT catalysts had redox-acidity bifunctional properties suitable for dimethoxymethane (DMM) synthesis, and the DMM selectivity was closely related to the reducibility and acidic sites.