Effect of Bi promoter on the performances of selective oxidation of isobutane to methacrolein over MoVO/AlPO4 catalysts

The effects of Bi on the catalytic performance of selective oxidation of isobutane to methacrolein over MoVO/AlPO₄ catalyst were investigated by XRD, FT-Raman, XPS, UV-vis DRS techniques. The results show that the addition of Bi component into the MoVO/AlPO₄ catalyst obviously improves the catalytic performance, and the selectivity to methacrolein can increase from 14.2% to 45.1% with the increase of Bi/V molar ratio from 0 to 1. Combining the characterization results with the reaction evaluation, it is concluded that the catalytic activities of the MoV_0.3Bi_x/AlPO₄ catalysts are related to the crystalline phase composition and the dispersion of molybdenum and vanadium oxides species in general, and also to the V⁵⁺/V⁴⁺ molar ratio on the surface in particular.