Characterization and performance of V2O5–TiO2 catalysts prepared by rapid combustion method

The VOx–TiO2 (VT) catalysts were prepared by the rapid combustion (RC) method and characterized by SEM, XRD, Raman, XPS, NH3-TPD and H2-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)VxO2. The XRD and Raman results revealed that the vanadia transformed from the isolated VOx to polymeric VOx and then as crystalline V2O5 on the surface of VxTi(1−x)O2. The polymeric VOx was predominant when V2O5 content was 30 wt.%. The H2-TPR and NH3-TPD results showed that the polymeric VOx exhibited more acidic sites and stronger reducibility than isolated VOx and crystalline V2O5. The catalytic activity result showed that the polymeric VOx 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.