Abstract
Catalytic vapor phase ammoxidation reaction of o-xylene was investigated. The activity of the vanadium pentoxide (V2O5)-pumice catalyst to the formation of o-phthalonitrile was low, and gave mainly phthalimide. Therefore the effect of addition of various additives on V2O5 was investigated. It was found that the addition of P2O5 to V2O5 gave remarkable improvement in the activity of formation of o-ph-thalonitrile. Namely, V2O5-P2O5-fire-resisted stone catalyst under the reacting condition (molar ratio of P2O5/V2O5=0.25, reaction temperature 480°c, gas space velocity 790 cc/cc. hr (NTP) NH3/o-xylene ca. 8 moles) yielded ca. 50 mole% o-phthal- onitrile and ca. 12 mole % of phthalimide. An increase in the activity for formation of o-phthalonitrile by the addition of P2O5 was probably brought by the lowering of activity for the oxidative decomposition of ammonia by the catalyst and of the excessive oxidation of o-xylene and by the increasing activity for the formation of o-phthalonitrile by the reaction of oxidation product of o-xylene with ammonia. Also, V2O5-P2O5-fire-resisted stone catalyst showed the high activity for the oxidative decomposition of ammonia at the initial period of reaction, which was gradually decreased to a fixed value with the time of reaction, while the rate of formation of o-phthalonitrile was low at the beginning, then reached to a fixed higher value after certain period.
