Selective Oxidation of Methanol to Green Oxygenates: Influence of Calcination Temperature on a $$\:\text{V}{\text{O}}_{\text{x}}\text{/Ti}{\text{O}}_{\text{2}}$$ Catalyst

Various VOx/TiO2 catalysts were prepared by equilibrium adsorption and calcined at different temperatures between 300 and 600 °C for performing the heterogeneously catalyzed selective methanol oxidation to oxygenates. The influence of calcination temperature on catalyst morphology and characteristics was studied by N2 sorption (BET and BJH), TPD, TPR, SEM, XRD, and UV-Vis diffusive reflectance spectra measurements. The effect on catalytic activity was investigated by experiments in a laboratory scale fixed bed reactor. It was found that the temperature of calcining has a significant influence on catalyst structure and performance due to a phase transition of the TiO2 support from anatase to rutile and, consequently, sintering effects, resulting in a loss of surface area, active sites, and catalytic activity. The catalyst calcined at 400 °C offered the overall best performance with a maximum yield of methyl formate of 64%, dimethoxymethane of 23%, and dimethyl ether of 2%, providing a sustainable way to produce green oxygenates by heterogeneous catalysis in the gas phase.