Oxidation and ammoxidation of toluene and benzyl alcohol over silico-aluminophosphate and metal-silico-aluminophosphate catalysts

Abstract

The silico-aluminophosphate (SAPO), vanadium-aluminophosphate (VAPO) and vanadium-silico-aluminophosphate (VSAPO) catalysts were synthesized by hydrothermal method. Depending on silicon and vanadium content, the as-synthesized molecular sieves were thermally stable or unstable up to 400-450°C. The catalysts were characterized by XRD, IR, TG and sorption methods. The oxidation and ammoxidation reactions of toluene and benzylalcohol were carried out over SAPO, VAPO and VSAPO catalysts. The catalysts were selective in the oxidation and ammoxidation of toluene. The yield of benzonitrile was 20-92 wt.-%. The vanadium and Sb₂O₃ modification enhances the yield of benzonitrile substantially. The benzoic acid was not observed in the products. In the ammoxidation of benzylalcohol, the yield of benzonitrile was 18%-74%. The selectivity of benzonitrile was comparatively lower. The reaction scheme is discussed. We report silico-aluminophosphate, VSAPO and TiSAPO, as-synthesized molecular sieves, as a new and novel class of oxidation and ammoxidation catalysts.