Partial oxidation of ethylbenzene by H2O2 on VOx/HZSM-22 catalyst

Abstract

A series of VO_x/HZSM-22 catalysts for the partial oxidation of ethylbenzene was prepared with 0.09–2.86 wt% V loading by an incipient wetness impregnation method, and the catalysts were characterized by inductively coupled plasma-atomic emission spectrometer, X-ray diffraction, Fourier transform infrared spectroscopy, N₂ physisorption analysis, X-ray photoelectron spectroscopy, diffuse reflectance ultraviolet-visible spectroscopy, temperature-programmed calcination-mass spectroscopy, and temperature-programmed hydrogen reduction. The results showed that the chemical nature of vanadium species on HZSM-22 depended on V loading. The amount of vanadium species incorporated into the framework of HZSM-22 increased with V loading firstly and reached a relatively stable value of about 0.2 wt%. The decomposed ammonia might reduce V⁵⁺ to V⁴⁺ in the calcination process. Highly dispersed extra-framework vanadium species, especially surface extra-framework V⁴⁺, promised a good effect on the oxidation of ethylbenzene, under optimized conditions, a high yield of 17.5% with 72.5% selectivity to acetophenone was obtained.