Mitsubishi Gas Chemical Company, Inc.

Takuji Shitara

Kenichi Nakamura

Kazuhiko Amakawa

Fumisada Kosuge

Shuji Ebata

Fumio Tanaka

Shuichi Ueno

Takashi Okawa

Susumu Otsuka

Susumu {overscore (O)}tsuka

A method of recovering ammonia by the distillation of an aqueous solution containing ammonia, carbon dioxide and hydrogen cyanide. The distillation is conducted using a distillation apparatus having at least its portion which comes into contact with the aqueous solution made of an alloy 1 or alloy 2. The alloy 1 contains 3% by weight or more of molybdenum, 15% by weight or more of nickel and 15% by weight or more of chromium. The alloy 2 contains 1% by weight or more of molybdenum, 9% by weight or less of nickel and 20% by weight or more of chromium. The use of the alloy 1 or alloy 2 prevents the corrosion of the distillation apparatus and enables the stable recovery of ammonia for a long period of time.

Method of recovering ammonia

A reactor for producing a nitrile compound from a carbon ring or heterocyclic compound having organic substituents by a gas phase reaction using a fluidized catalyst bed with ammonia and a gas containing oxygen. In a cylindrical fluidized catalyst bed having a diameter of 2.0 meters or greater, partial vaporization-type cooling tubes (the cooling medium is partially vaporized in the tubes) and complete vaporization-type cooling tubes (the cooling medium is completely vaporized in the cooling tubes) are disposed in a specific arrangement. Water containing ionic SiOin 0.1 ppm or smaller and having an electric conductivity of 5 &#x3bc;S/cm or smaller is used as the cooling medium for the complete vaporization-type cooling tubes. The temperature of the reaction is easily stabilized and uniform distribution of temperature is obtained in the fluidized catalyst bed. Stable continuous operation is achieved for a long time in a commercial scale apparatus.

Reactor for producing a nitrile compound and method for operating the reactor

In a process for producing a nitrile compound comprising introducing a carbon ring or heterocyclic compound having organic substituents, ammonia and the air into a reactor and reacting the introduced compounds in the presence of a catalyst, during the reaction, a residual gas obtained after the formed nitrile compound is separated from a reaction gas discharged from the reactor is recycled to the reactor in an amount of 10 to 60% by volume based on the amount of the fresh raw material gas supplied to the reactor and the ratio of the amount by mole of molecular oxygen to the amount by mole of the organic substituent in the carbon ring or heterocyclic compound having organic substituents supplied to the reactor (O/organic substituent) is kept within 1.5 to 7. The reaction is achieved under an advantageous condition and the nitrile compound can be produced industrially advantageously at a higher yield.

Process for producing a nitrile compound

In a process for producing a polynitrile compound comprising introducing a polysubstituted organic compound (POC) which is a carbon ring or heterocyclic compounds having a plurality of organic substituents into a reactor with ammonia and a gas containing oxygen and ammoxidizing POC in the presence of a catalyst, at least a portion of the unreacted POC and a mononitrile compound of an intermediate product in the reaction gas discharged from the reactor is separated, recovered and recycled to the reactor so that the flow rate of the mononitrile compound at the outlet of the reactor is 2 to 16% by mole of the total flow rate of POC and the mononitrile compound supplied to the reactor. Burning reaction of the side reaction is suppressed and the loss of POC can be decreased without adverse effects on productivity and the polynitrile compound can be obtained at a high yield.

Process for producing a polynitrile compound

In the process of the present invention, xylylenediamine and/or cyanobenzylamine is produced by a catalytic liquid-phase hydrogenation of a phthalonitrile compound. The liquid-phase hydrogenation is performed by controlling the concentration of a benzamide compound to a specific level or lower. In a preferred embodiment, the concentration of a benzoic acid compound is further controlled to a specific level or lower. By the process, xylylenediamine and/or cyanobenzylamine is produced at high yields and the catalyst life is prolonged.

Process for production of xylylenediamine and/or cyanobenzylamine

In a method for producing xylylenediamine by hydrogenating phthalonitrile separated from a gas produced by causing xylene to react with ammonia and oxygen-containing gas in the presence of a catalyst, (1) the gas is brought into contact with an organic solvent to trap phthalonitrile; (2) a liquid in which phthalonitrile is trapped is distilled, to thereby recover phthalonitrile and the organic solvent from the top of the column and separate at the bottom of the column impurities having boiling points higher than that of phthalonitrile; (3) the organic solvent is recovered from the top of the column and liquefied phthalonitrile of high purity is recovered at the bottom of the column; and (4) the phthalonitrile is hydrogenated after mixing with liquid ammonia and at least one solvent selected from aromatic hydrocarbon and saturated hydrocarbon. Thus, high-purity phthalonitrile is produced at high yield industrially efficiently.

Method for producing high purity xylylenediamine

In a method for separating isophthalonitrile from a gas produced by causing m-xylene to react with ammonia and oxygen-containing gas in the presence of a catalyst, the gas is brought into contact with an organic solvent having a boiling point lower than that of isophthalonitrile; a liquid in which isophthalonitrile is trapped in a trapping step is distilled, to thereby recover isophthalonitrile and the organic solvent from the top of the column and separate at the bottom of the column impurities having boiling points higher than that of isophthalonitrile; and the organic solvent is recovered from the top of the rectification column and liquefied isophthalonitrile of high purity is recovered at the bottom of the column. Thus, loss of isophthalonitrile and plugging of a vacuum-evacuation system caused by isophthalonitrile migrating from a condensation system during distillation under reduced pressure can be prevented, and high-purity isophthalonitrile can be produced at high yield constantly for a long period of time.

Method of purifying isophthalonitrile

A method for producing xylylenediamine by hydrogenating phthalonitrile synthesized through ammoxidation of xylene, wherein phthalonitrile is trapped in an organic solvent (A) by bringing a gas produced through ammoxidation into direct contact with the organic solvent (A), and hydrogenation including adding liquid ammonia to the resultant mixture is carried out without separation of phthalonitrile trapped in the organic solvent (A). Through this method, the phthalonitrile can be readily recovered from the produced gas and at high yield without need for new equipment, and xylylenediamine can be efficiently produced through hydrogenation. Xylylenediamine of high purity can be obtained by subjecting the produced xylylenediamine to extraction by use of an organic solvent (B) and water.

Method for producing xylylenediamine

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.

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Niigata, Japan

Takuji Shitara