The Role of V‐Species and O‐Species on Controlled‐Hydrogen‐Reduction VOx Surfaces in Cyclohexane Oxidation

Abstract

AbstractA series of controlled‐hydrogen‐reduction VOx (CHR‐VOx) were prepared after our controllable hydrogen treatment, and CHR‐VOx were controlled to be reduced to the states dominated by V5+ and V4+ species, subsequently the catalytic roles of V‐species and O‐species for cyclohexane (CHA) oxidation were explored. As expected, the surface properties of CHR‐VOx have occurred remarkable change resulting in a significantly improvement on catalytic performance determined by V‐species and O‐species. The reduction behavior of the properties was recognized by XPS and Raman. Generally, the moderate‐reduced CHR‐VOx which possessed most 78.7 % multi‐liganded‐oxygen (LO) performed the best conversion for CHA (11.8 %), and the over‐reduced CHR‐VOx with a large content of V4+ species (33 %) performed a best selectivity for adipic acid (44.3 %). In this case, LO sites were regarded as the active site to accelerate the activation of CHA, while V4+ species were regarded as the oxygen vacancies (OVs) through V4+−OV to contribute to the further oxidation to adipic acid.