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

Abstract

A 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.