Regeneration method of working solution

A regeneration method of a working solution is herein disclosed in which various by-products which do not participate in the production of hydrogen peroxide and which are present in the working solution in a hydrogen peroxide production process utilizing an anthraquinone method can efficiently be converted into anthraquinones effective as reaction media for the production of hydrogen peroxide.The present invention is concerned with (1) a regeneration method of a working solution wherein at least a part of the unreduced working solution is brought into contact with a catalyst mainly comprising a .gamma.-alumina at a temperature of 40 to 150.degree. C., and (2) another regeneration method of a working solution wherein the working solution is brought into contact with a catalyst mainly comprising a .gamma.-alumina at a temperature of 20 to 150.degree. C. under conditions that a concentration h (mol/liter) of the alkyltetrahydroanthrahydroquinones in the working solution before the catalytic treatment meets the equation(0.0018.times.t-0.0285).times.h<0.05WHEREIN t is a treatment temperature (.degree.C.), to convert alkyltetrahydrooxyanthrones in the working solution into the alkyltetrahydroanthrahydroquinones.

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Claims

1. A method for regenerating a working solution containing an anthraquoinone dissolved in at least one solvent selected from the group consisting of trimethylbenzene and diisobutylcarbinol, from a process for producing hydrogen peroxide by repeatedly reducing and oxidizing the working solution, wherein the antraquinone in the working solution comprises at least one alkyltetrahydroanthraquinone selected from the group consisting of amyltetrahydroanthraquinone, ethyltetrahydroanthraquinone and t-butyltetrahydroanthraquinone, the method comprising bringing the working solution into contact with a catalyst comprising a.gamma.-alumina and having a particle size of 8 to 100 mesh at a treatment temperature of 20.degree. to 150.degree. C. under conditions that a concentration h (mol/liter) of the at least one alkyltetrahydroanthrahydroquinone in the working solution before the contact with the catalyst satisfies the following equation:

2. The method according to claim 1 wherein the concentration h (mol/liter) of the at least one alkyltetrahydroanthrahydroquinone in the working solution before the contact with the catalyst is 0.15 mol/liter or less and satisfies the following equation:

3. The method according to claim 1, wherein the catalyst has a particle size of 8 to 100 mesh.

4. The method according to claim 3, wherein the method is carried out in a stirrer-equipped reactor, a fixed bed reaction or a fluidized bed reactor.

5. The method according to claim 1, wherein the working solution which is brought into contact with the catalyst comprises amyltetrahydroanthraquinone and amyltetrahydrooxyanthrone.

6. The method according to claim 5, wherein said at least one solvent comprises 1,2,4-trimethylbenzene and diisobutylcarbinol.

7. The method according to claim 6, wherein the treatment temperature is 60.degree. C.

8. The method according to claim 6, wherein the treatment temperature is 100.degree. C.

9. The method according to claim 6, wherein the treatment temperature is 120.degree. C.

Referenced Cited
U.S. Patent Documents
2739875 March 1956 Sprauer et al.
3432267 March 1969 Lee et al.
3752885 August 1973 Liebert et al.
3880596 April 1975 Liebert et al.
3965251 June 22, 1976 Shin et al.
4566998 January 28, 1986 Ochoa et al.
5399333 March 21, 1995 Kato et al.
Foreign Patent Documents
2003268 July 1971 DEX
Other references
  • Sandelin, Fredrik, et al., "Kinetics of the Catalys Deactivation in the Recovery of Active Anthraquinones", Catalyst Deactivation (1994),Studies in Surface Science and Catalysis, vol. 88, 635-640 (1994).
Patent History
Patent number: H1787
Type: Grant
Filed: Mar 26, 1997
Date of Patent: Feb 2, 1999
Inventors: Kazuharu Ogasawara (Kamisu-machi, Kashima-gun, Ibaraki-ken), Tomio Kato (Katsushika-ku, Tokyo), Kazuyuki Minato (Katsushika-ku, Tokyo), Kenji Kato (Katsushika-ku, Tokyo), Makoto Sumitani (Katsushika-ku, Tokyo)
Primary Examiner: Charles T. Jordan
Assistant Examiner: Meena Chelliah
Application Number: 8/829,696