The Effect of Vanadium Loading on the Performance of Ti-phosphate-supported V2O5 Catalyst in the Selective Oxidation of o-xylene to Phthalic Anhydride

In this work, the performance of Ti-phosphate-supported vanadium (v) oxide catalyst in The reaction of phthalic anhydride production by selective catalytic oxidation of o-xylene was investigated. Four catalyst samples with the active phase of 2, 7, 12 and 15 wt% were made in order to investigate the effect of vanadium loading.To determine the characteristics of samples, a number of experiments such as BET, XRD, SEM, NH3-TPD, and TGA were done. Moreover, the reactor test was carried out in order to evaluate activity and selectivity to phthalic anhydride. According to XRD patterns before the reaction, titania was observed in the anatase phase which was the desirable phase for the reaction of o-xylene oxidation to phthalic anhydride. With increasing vanadium loading, the number of acidic sites on catalyst surface decreases. In addition, the catalytic activity and selectivity to phthalic anhydride were improved. At high values of vanadium, the effect of active phase loading on the catalytic performance decreased due to the formation of V2O5 on the catalyst surface. 15V-Tip sample had the most selectivity to phthalic anhydride with values of 37% at the temperature of 450oC.