3,4-Dichlorotoluene Ammoxidation to 3,4-Dichlorobenzonitrile over VPO/SiO2 Catalyst

Ammoxidation of 3,4-dichlorotoluene(DCT) to prepare 3,4-dichlorobenzonitrile (DCBN) over silica supported vanadium phosphorus oxide catalysts has been studied. On the VPO/SiO2 catalyst, the influence of the reaction temperature, the molar ratio of air/DCT, the molar ratio of NH3/DCT in the feed gas and the space velocity (vs) on the conversion, yield and selectivity was observed. The most appropriate reaction condition is: reaction T=673 K, n(DCT)∶n(NH3)∶n(air)=1∶7∶30 and vs=250 h-1. At this optimum reaction condition, the conversion of DCT is 97.8%; the molar yield of DCBN is 67.4%. It was found that the addition of element phosphorus can improve the yield of DCBN compared with VO/SiO2 catalyst.