Process for producing nitrile compounds

摘要

There is disclosed a process for producing a nitrile compounds by ammoxidation of a carbocyclic or heterocyclic compound having organic substituent(s) by reacting the compound with ammonia and an oxygen-containing gas, wherein unreacted ammonia is recovered from the reaction product gas and recycled to the reaction system. In the first process of the present invention, the ammoxidation is conducted by vapor-phase catalytic reaction in the presence of a fluid catalyst containing at least one metal oxide selected from the group consisting of vanadium oxide, molybdenum oxide and iron oxide while controlling a water concentration of a gas fed to a reactor to 12% by volume or lower by adjusting a water content of the recovered ammonia by distillation, thereby avoiding deterioration in activity of the catalyst due to recycle of the recovered ammonia. As a result, it is possible to stably obtain the aimed product at a high yield for a long period of time. In the second process of the present invention, after separating the nitrile compounds from the reaction product gas, unreacted ammonia and hydrogen cyanide contained in the residual gas are absorbed into water. Then, the obtained solution is distilled under a pressure of 0.2 to 0.7 MPa to recover ammonia and hydrogen cyanide from the residual gas and recycle these compounds to reaction system. As a result, the ammonia and hydrogen cyanide can be efficiently recovered at the same time, and it is possible to not only reduce costs required for treatment of wastes or the like, but also stably obtain the aimed nitrile compounds at a high yield for a long period of time.