シアノベンゼン類の接触的合成法に関する研究(第5報)

o-キシレンの気相接触アンモオキシディション反応

抄録

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.