Vanadium-zirconium catalyst on different support for hydroxylation of benzene to phenol with O2 as the oxidant

Vanadium-zirconium catalyst was prepared with zirconium tetrachloride and ammonium metavanadate, which were supported on different supports, such as activated carbon, g-C3N4, MWCNTs (multiwall carbon nano tubes), acidified MWCNTs, bentonite, and gamma-Al2O3. Various techniques were employed to characterize the catalysts such as X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption, and Raman spectrum. It was found that Zr4+ and V5+ in the vanadium-zirconium catalyst were dispersed on support in the form of zirconium pyrovanadate. The performance of catalysts on hydroxylation of benzene to phenol with O-2 as the oxidant was investigated. The vanadium-zirconium catalyst with different supports showed different catalytic performance and the reason was studied. It was found that the catalytic performance was related to the nature of the supports including the surface area and the composition of the supports. The yield of phenol reached to 8.6% and selectivity reached to about 80% when the activated carbon acted as support. Kinetic study showed that the first step of the consecutive reaction was first order for benzene and the second step was first order for phenol.