Method and apparatus for producing dicyanobenzene

Patent metadata

Field	Value
Publication number	US-9822062-B2
Application number	US-201515025812-A
Country	US
Kind code	B2
Filing date	Mar 9, 2015
Priority date	Mar 10, 2014
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

The object is to prevent deterioration and loss of dicyanobenzene in producing dicyanobenzene by ammoxidation of xylene to thereby achieve industrial and economical advantage in producing of dicyanobenzene. The method for producing dicyanobenzene of the present invention includes: contacting a xylene-ammoxidation reaction gas containing dicyanobenzene in ammoxidation of xylene with an organic solvent so as to obtain a dicyanobenzene-absorbing solution; contacting the dicyanobenzene-absorbing solution with a basic aqueous solution containing a salt such as ammonium carbonate so as to extract a water-soluble salt formed by neutralization reaction between carboxylic acid in the dicyanobenzene-absorbing solution and a base in the basic aqueous solution into an aqueous phase; separating the mixture of the dicyanobenzene-absorbing solution and the basic aqueous solution into an organic phase and an aqueous phase; decomposing the salt such as ammonium carbonate contained in the organic phase for separation of the salt from the organic phase; and distilling the organic phase to separate low boiling point compounds contained in the organic phase from the organic phase so as to obtain dicyanobenzene.

First claim

The invention claimed is:

1. A method for producing dicyanobenzene comprising:
(1) an absorption step of contacting a xylene-ammoxidation reaction gas comprising dicyanobenzene obtained by ammoxidation of xylene with an organic solvent so as to obtain a dicyanobenzene-absorbing solution comprising the organic solvent in which the dicyanobenzene is dissolved;
(2) an extraction step of contacting the dicyanobenzene-absorbing solution with a basic aqueous solution comprising one or more salts selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium carbamate so as to extract a water-soluble salt formed by neutralization reaction between carboxylic acid in the dicyanobenzene-absorbing solution and a base in the basic aqueous solution into an aqueous phase;
(3) a liquid-liquid separation step of separating a mixture of the dicyanobenzene-absorbing solution and the basic aqueous solution after the extraction step into an organic phase and an aqueous phase;
(4) a degassing step of decomposing one or more salts selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium carbamate contained in the organic phase after the liquid-liquid separation step so as to separate the one or more salts from the organic phase; and
(5) a low-boiling-point compound separation step of distilling the organic phase after the degassing step to separate components contained in the organic phase and having a boiling point lower than that of the dicyanobenzene, from the organic phase so as to obtain the dicyanobenzene.

2. The method according to claim 1 , wherein a pressure of a gas phase in the degassing step is 101.3 kPa or less.

3. The method according to claim 1 , wherein a temperature of a liquid phase in the degassing step is 70 to 180° C.

4. The method according to claim 1 , wherein the base in the extraction step is ammonia in an amount in a number of moles 1 to 50 times the total number of moles of the carboxylic acid contained in the dicyanobenzene-absorbing solution.

5. The method according to claim 1 , wherein the basic aqueous solution is contacted with the dicyanobenzene-absorbing solution under a temperature condition of 140° C. or lower in the extraction step.

6. The method according to claim 1 , wherein the xylene is meta-xylene and the dicyanobenzene is isophthalonitrile.

7. The method according to claim 1 , wherein a catalyst for use in the ammoxidation reaction is a catalyst which contains vanadium and/or chromium.

8. The method according to claim 1 , wherein the organic solvent which absorbs the dicyanobenzene in the absorption step is one or more organic solvents selected from the group consisting of an alkylbenzene, a heterocyclic compound, an aromatic nitrile compound and a heterocyclic nitrile compound.

9. A method for producing xylylenediamine from the dicyanobenzene obtained by the producing method according to claim 1 , comprising a hydrogenation step of dissolving the dicyanobenzene in a solvent and subsequently hydrogenating the dicyanobenzene in a liquid phase in the presence of a catalyst.

10. An apparatus for producing dicyanobenzene comprising:
(1) absorption means for contacting a xylene-ammoxidation reaction gas comprising dicyanobenzene obtained by ammoxidation of xylene with an organic solvent so as to obtain a dicyanobenzene-absorbing solution comprising the organic solvent in which the dicyanobenzene is dissolved;
(2) extraction means for contacting the dicyanobenzene-absorbing solution with a basic aqueous solution comprising one or more salts selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium carbamate so as to extract a water-soluble salt formed by neutralization reaction between carboxylic acid in the dicyanobenzene-absorbing solution and a base in the basic aqueous solution into an aqueous phase;
(3) liquid-liquid separation means for separating a mixture of the dicyanobenzene-absorbing solution and the basic aqueous solution sent from the extraction means into an organic phase and an aqueous phase;
(4) degassing means for decomposing one or more salts selected from the group consisting of ammonium carbonate, ammonium bicarbonate, and ammonium carbamate contained in the organic phase sent from the liquid-liquid separation means, so as to separate the one or more salts from the organic phase; and
(5) low-boiling-point compound separation means for distilling the organic phase sent from the degassing means to separate components contained in the organic phase and having a boiling point lower than that of the dicyanobenzene, from the organic phase so as to obtain the dicyanobenzene.

11. The method according to claim 2 , wherein a temperature of a liquid phase in the degassing step is 70 to 180° C.

12. The method according to claim 2 , wherein the base in the extraction step is ammonia in an amount in a number of moles 1 to 50 times the total number of moles of the carboxylic acid contained in the dicyanobenzene-absorbing solution.

13. The method according to claim 2 , wherein the basic aqueous solution is contacted with the dicyanobenzene-absorbing solution under a temperature condition of 140° C. or lower in the extraction step.

14. The method according to claim 2 , wherein the xylene is meta-xylene and the dicyanobenzene is isophthalonitrile.

15. The method according to claim 2 , wherein a catalyst for use in the ammoxidation reaction is a catalyst which contains vanadium and/or chromium.

16. The method according to claim 2 , wherein the organic solvent which absorbs the dicyanobenzene in the absorption step is one or more organic solvents selected from the group consisting of an alkylbenzene, a heterocyclic compound, an aromatic nitrile compound and a heterocyclic nitrile compound.

17. A method for producing xylylenediamine from the dicyanobenzene obtained by the producing method according to claim 2 , comprising a hydrogenation step of dissolving the dicyanobenzene in a solvent and subsequently hydrogenating the dicyanobenzene in a liquid phase in the presence of a catalyst.

18. The method according to claim 3 , wherein the base in the extraction step is ammonia in an amount in a number of moles 1 to 50 times the total number of moles of the carboxylic acid contained in the dicyanobenzene-absorbing solution.

19. The method according to claim 3 , wherein the basic aqueous solution is contacted with the dicyanobenzene-absorbing solution under a temperature condition of 140° C. or lower in the extraction step.

20. The method according to claim 3 , wherein the xylene is meta-xylene and the dicyanobenzene is isophthalonitrile.

Assignees

• Mitsubishi Gas Chemical Co

Inventors

• IBI Yukiya
• Kumano Tatsuyuki
• Wakita Natsumi

Classifications

• B01D1/0082

  Regulation; Control · CPC title

• B01D53/1418

  Recovery of products · CPC title

• C07C253/34

  Separation; Purification · CPC title

• B01D3/14

  Fractional distillation {or use of a fractionation or rectification column} · CPC title

• B01D17/0214

  with removal of one of the phases · CPC title