EP-4737435-A1 - METHOD FOR PRODUCING XYLYLENEDIAMINE

Abstract

Provided is a xylylenediamine production method including: a first hydrogenation step of supplying dicyanobenzene and hydrogen-containing gas G1 in the presence of a catalyst having hydrogenation ability to a reactor to obtain xylylenediamine by hydrogenation of the dicyanobenzene; a treatment step of interrupting the hydrogenation and supplying hydrogen-containing gas G2 comprising recycled gas to the reactor to bring the catalyst that has undergone the first hydrogenation step into contact with the hydrogen-containing gas G2; and a second hydrogenation step of resuming the hydrogenation in the presence of the catalyst that has undergone the treatment step, wherein the recycled gas is obtained by removing at least a part of an organic compound from exhaust gas emitted from the reactor through the contact.

Inventors

• YOKOO, Kazuma
• IBI, YUKIYA
• KUMANO, TATSUYUKI

Assignees

• MITSUBISHI GAS CHEMICAL COMPANY, INC.

Dates

Publication Date

20260506

Application Date

20240507

Claims (8)

1. A xylylenediamine production method comprising: a first hydrogenation step of supplying dicyanobenzene and hydrogen-containing gas G1 in the presence of a catalyst having hydrogenation ability to a reactor to obtain xylylenediamine by hydrogenation of the dicyanobenzene; a treatment step of interrupting the hydrogenation and supplying hydrogen-containing gas G2 comprising recycled gas to the reactor to bring the catalyst that has undergone the first hydrogenation step into contact with the hydrogen-containing gas G2; and a second hydrogenation step of resuming the hydrogenation in the presence of the catalyst that has undergone the treatment step, wherein the recycled gas is obtained by removing at least a part of an organic compound from exhaust gas emitted from the reactor through the contact.
2. The xylylenediamine production method according to claim 1, wherein the recycled gas is obtained by removing at least a part of the organic compound from the exhaust gas using a gas-liquid separator.
3. The xylylenediamine production method according to claim 2, wherein a supply temperature of the exhaust gas to the gas-liquid separator is 5°C to 80°C.
4. The xylylenediamine production method according to claim 1 or 2, wherein in the treatment step, a contact temperature between the hydrogen-containing gas G2 and the catalyst that has undergone the first hydrogenation step is 200°C to 500°C.
5. The xylylenediamine production method according to claim 1 or 2, wherein a hydrogen concentration of the hydrogen-containing gas G2 is 1 vol% or more.
6. The xylylenediamine production method according to claim 1 or 2, wherein in the treatment step, at least a part of the catalyst is washed with a solvent before the supply of the hydrogen-containing gas G2 to the reactor.
7. The xylylenediamine production method according to claim 1 or 2, wherein the reactor is a fixed-bed reactor.
8. The xylylenediamine production method according to claim 1 or 2, wherein the catalyst comprises nickel and/or cobalt.

Description

Technical Field The present invention relates to a xylylenediamine production method. Background Art Xylylenediamine is useful as a starting material for polyamide resins, curing agents, and the like, and as an intermediate material for isocyanate resins and the like. A method for producing xylylenediamine typically includes a method of hydrogenating dicyanobenzene in the presence of a catalyst. As a specific example thereof, Patent Literature 1, for example, proposes that a catalyst whose activity has been reduced by use in the hydrogenation reaction of dicyanobenzene is subjected to regeneration treatment by the following steps (1) and (2) and then reused as a catalyst in a reaction system: (1) the step of bringing the catalyst into contact with hydrogen-containing gas at a temperature that falls within the range of 140 to 200°C and has an average temperature of 180°C or lower for 1 hour or longer; and(2) the step of further bringing the catalyst thus treated by the contact into contact with hydrogen-containing gas at a temperature in the range of 200 to 500°C. Citation List Patent Literature Patent Literature 1: Japanese Patent No. 4561063 Summary of Invention Technical Problem The method described in Patent Literature 1 permits drastic reduction in catalyst cost and is therefore advantageous, because a catalyst with reduced activity can be reused. On the other hand, in Patent Literature 1, sufficient studies have hardly been made on the composition of gas for treating the catalyst, for example. Thus, the method still has room for improvement from the viewpoint of production efficiency. The present invention has been made in light of these problems, and an object of the present invention is to provide a xylylenediamine production method that enables a catalyst to be used for a long period in hydrogenation of dicyanobenzene and is also excellent in production efficiency. Solution to Problem The present inventors have conducted diligent studies to attain the object and consequently completed the present invention by finding that the object can be attained, for example, by treating exhaust gas in the regeneration treatment of a catalyst and then bringing the gas into contact with the catalyst after use. Specifically, the present invention encompasses the following aspects. [1] A xylylenediamine production method comprising: a first hydrogenation step of supplying dicyanobenzene and hydrogen-containing gas G1 in the presence of a catalyst having hydrogenation ability to a reactor to obtain xylylenediamine by hydrogenation of the dicyanobenzene;a treatment step of interrupting the hydrogenation and supplying hydrogen-containing gas G2 comprising recycled gas to the reactor to bring the catalyst that has undergone the first hydrogenation step into contact with the hydrogen-containing gas G2; anda second hydrogenation step of resuming the hydrogenation in the presence of the catalyst that has undergone the treatment step, whereinthe recycled gas is obtained by removing at least a part of an organic compound from exhaust gas emitted from the reactor through the contact.[2] The xylylenediamine production method according to [1], wherein the recycled gas is obtained by removing at least a part of the organic compound from the exhaust gas using a gas-liquid separator.[3] The xylylenediamine production method according to [2], wherein a supply temperature of the exhaust gas to the gas-liquid separator is 5°C to 80°C.[4] The xylylenediamine production method according to any of [1] to [3], wherein in the treatment step, a contact temperature between the hydrogen-containing gas G2 and the catalyst that has undergone the first hydrogenation step is 200°C to 500°C.[5] The xylylenediamine production method according to any of [1] to [4], wherein a hydrogen concentration of the hydrogen-containing gas G2 is 1 vol% or more.[6] The xylylenediamine production method according to any of [1] to [5], wherein in the treatment step, at least a part of the catalyst is washed with a solvent before the supply of the hydrogen-containing gas G2 to the reactor.[7] The xylylenediamine production method according to any of [1] to [6], wherein the reactor is a fixed-bed reactor.[8] The xylylenediamine production method according to any of [1] to [7], wherein the catalyst comprises nickel and/or cobalt. Advantageous Effect of Invention The present invention can provide a xylylenediamine production method that enables a catalyst to be used for a long period in hydrogenation of dicyanobenzene and is also excellent in production efficiency. Description of Embodiments Hereinafter, the embodiment for carrying out the present invention (hereinafter, referred to as the "present embodiment") will be described in detail. The present embodiment given below is an illustration for describing the present invention and does not intend to limit the present invention to the contents described below. The present invention can be carried out through appropr