Mitsubishi Gas Chemical Company, Inc.

Kenji Nakaya

Shinichi Nagao

Tatsuyuki Kumano

Ryusuke Shigematsu

Kinji Kato

Masato Inari

Jitsuo Oishi

Hiroshi Machida

The invention provides a process for producing xylylenediamine, including supplying a solution of phthalonitrile dissolved in a solvent to a reactor filled with a catalyst and hydrogenating the phthalonitrile to produce xylylenediamine, characterized in that the process includes halting supply of the solution; (2) bringing a washing liquid into contact with the catalyst, the washing liquid having a phthalonitrile content of 3 mass % or less and a xylylenediamine content of 1 mass % or more; and after completion of the contact, resuming supply of the solution, and employing the catalyst continuously in hydrogenation. Through the production process of the invention, the catalyst can be employed continuously for a long period of time, and the catalyst-related cost can be considerably reduced.

Process for producing xylylenediamine

A method of producing xylylenediamine by the hydrogenation of dicyanobenzene obtained by the ammoxidation of xylene in a high yield while prolonging the catalyst life. In the method, a molten dicyanobenzene from which compounds having a boiling point lower than that of dicyanobenzene have been removed but compounds having a boiling point higher than that of dicyanobenzene are not removed is dissolved in a solvent containing liquid ammonia. By this dissolution, at least part of dicyanobenzene polymers precipitates as insolubles. The precipitates are removed by a solid-liquid separation. By subjecting the resulting solution containing the dicyanobenzene polymers in a reduced amount to hydrogenation, xylylenediamine is produced in a high yield and the life time of hydrogenation catalyst is prolonged.

Production method of xylylenediamine

A method of producing xylylenediamine by a two-stage hydrogenation of a starting phthalonitrile in a solvent. The main steps of the method are a hydrogenation step 1 and a hydrogenation step 2. In the hydrogenation step 1, a solution of the starting phthalonitrile in the solvent containing liquid ammonia is fed to an inlet of a first reaction zone and the hydrogenation is carried out in the first reaction zone in the presence of a heterogeneous catalyst, to hydrogenate nitrile groups in the starting phthalonitrile to aminomethyl groups. A part of the hydrogenation product solution from the first reaction zone is circulated to the inlet of the first reaction zone and the rest is introduced into the hydrogenation step 2 where further undergoes the hydrogenation.

Production of xylylenediamines

A process for producing a high purity aromatic polycarboxylic acid (APA) by purification of a crude APA comprises: (I) aging a slurry of the crude APA in a first dispersion medium at 180 to 300&#xb0; C. for 10 minutes or longer under stirring; (II) introducing the aged slurry of the APA into a column for substituting dispersion media, bringing the slurry into contact with a second dispersion medium and separating the resultant fluid into a fluid of the first dispersion medium containing impurities and a slurry of the second dispersion medium containing crystals of the high purity APA; and (III) separating the crystals of the high purity APA from the slurry of the second dispersion medium. A high purity APA having excellent hue and particle diameter can be industrially advantageously produced while the construction of the process is simplified and the consumption of energy is decreased.

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Okayama, Japan

Kenji Nakaya