Contribution of Ca and V to enhancing coking-resistance and stability of MoV/CaO-intercalated montmorillonite catalyst in deoxydehydration of glycerol

Glycerol can be converted to allyl alcohol via deoxydehydration using molybdenum-vanadium, rhenium and iron based catalysts. However, the dehydration causes severe coking at strong acid sites on the surface of catalyst. Molybdenum-vanadium oxide supported on calcium oxide-intercalated montmorillonite (MoV-CaMMT) was prepared by oxalate anion intercalation followed by impregnation. MoV-CaMMT displayed the best catalytic performance of 86.5% glycerol conversion and good stability in 5 h. Correlating the results of XRD, XPS and TG analysis, it can be demonstrated that the addition of CaO in the catalyst preparation is conducive to the crystallization and dispersion of vanadium oxides, and reduces the acid strength, while the presence of a few vanadium dioxide and the stable conversion of V4+ and V5+ are the reasons for enhancing coking-resistance of MoV-CaMMT. Additionally, NH3-TPD analysis proved the coexistence of weak and strong acid sites in MoVOx, which are conducive to the formation of acetol.