The effect of Fe2O3 promotion on the ammoxidation of o-xylene with V-Cr-based catalyst

•The addition of Fe2O3 to the V-Cr-based catalyst could promote the formation of oxygen vacancies in the V2O5 on the catalyst surface as Fig. 13 showed, which accelerated the liquidity of lattice oxygen in the catalyst and improved the electron transfer ability of the catalysts.•Fe3+ could change the V4+/V5+ ratio of the V-Cr-based catalysts, which may affect the oxidation–reduction performance of the catalysts and be critical to improve the selectivity of target production.•Fe2O3 could improve the acid-base properties of the catalysts which would affect the ammonia and the oxygen adsorption on the catalysts surface, and then these properties may change the product distribution. A series of V-Cr-based catalysts with different Fe2O3 contents were prepared for o-xylene ammoxidation and their catalytic property was studied. The evaluation results showed that the appropriate Fe2O3 addition enhanced catalytic performance, and the best addition mass fraction was 0.5%. The conversion of o-xylene ammoxidation on the catalysts with different Fe2O3 contents increased from 53.8% to 94.7%, and the yield of the target product increased from 32.7% to 53.0%. It was found that the addition of Fe2O3 can change the physical properties and acid-base properties of the catalyst. An appropriate amount of Fe2O3 not only improved the amount of lattice oxygen vacancies in the catalyst and changed the adsorbed oxygen on the surface, but also adjusted the V+4 /V+5 ratio of active oxide V=O, which is conducive to the oxidation–reduction process, thus improving the performance of the catalyst. [Display omitted]