Organic compounds -- part of the class 532-570 series – Organic compounds – Polycyclo ring system containing anthracene configured ring...
Patent
1999-07-27
2000-08-15
Dees, Jose' G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Polycyclo ring system containing anthracene configured ring...
423588, C07C 4527, C01B 15023
Patent
active
061039179
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the process for preparing hydrogen peroxide from quinone compounds, and more specifically to a novel means for treating the working solutions used in this manufacturing process.
The common process for manufacturing hydrogen peroxide is the one known as the anthraquinone process. This process generally uses a mixture of substituted anthraquinone and anthrahydroquinone compounds such as, for example, 2-ethylanthraguinone (EAQ), 2-ethyl-5,6,7,8-tetrahydroanthraquinone (THEAQ), 2-ethylanthrahydroquinone (EAHQ) and 2-ethyl-5,6,7,8-tetrahydroanthrahydroquinone (THEAHQ). These compounds are generally dissolved in a mixture of polar and/or apolar solvents, the whole constituting what is conventionally referred to as the working solution.
This process for manufacturing hydrogen peroxide consists in carrying out successive reduction and oxidation cycles on the working solution.
Thus, according to the first step of the cycle, a catalytic hydrogenation of the working solution is carried out, which converts the anthraquinone into anthrahydroquinone. This hydrogenation is then followed by an assured oxidation in the presence of air, oxygen or a gaseous mixture containing oxygen. During this oxidation, the anthrahydroquinone is retrograded into anthraquinone with formation of hydrogen peroxide.
An extraction, generally in the presence of water, gives an aqueous hydrogen peroxide solution which can then be purified and concentrated.
In parallel, the working solution is regenerated in order to be used in the next oxidation/reduction cycle.
During the successive reduction and oxidation steps on the working solution, some of the starting anthraquinone compounds are slowly converted into degradation products which can have an influence on the yield for the synthesis of the hydrogen peroxide.
Thus, during the hydrogenation, side reactions lead in particular to oxathrones and anthranones, and, during the oxidation, to tetrahydroanthraquinone epoxides. These compounds are side products which give rise to an increase in the density and viscosity of the working solution and bring about deactivation of the hydrogenation catalyst, in the event of accumulation.
Moreover, during the reduction reactions, the starting anthraquinone compounds are converted into tetrahydroanthraquinones which give low degrees of oxidation, resulting in a loss of yield.
It is thus not recommended to use working solutions containing high proportions of these anthraquinone degradation products.
To solve this problem, U.S. Pat. No. 2,739,875 has proposed treating the working solutions, based on anthraquinone compounds and containing degradation products of these compounds, in order to regenerate them and reuse them in the process for the synthesis of hydrogen peroxide. According to that document, the working solution is placed in contact with activated alumina or magnesia while heating. The alumina has the effect of retrograding the anthraquinone degradation products into anthraquinone, in particular tetrahydroanthraquinone into anthraquinone and tetrahydroanthraquinone epoxides, and then into anthraquinone.
Patent FR 1,468,707 has also provided an improvement to this process for regenerating the working solution by proposing to use an alumina doped with an alkaline substance.
One aim of the present invention is to further improve the capacity of alumina to regenerate the anthraquinone degradation products and to ensure maintenance of the activity of the said alumina over a large number of regeneration cycles.
With this aim, the invention relates to a process for regenerating a working solution for the production of hydrogen peroxide, the said working solution containing at least one anthraquinone derivative and at least one degradation product of this derivative, this product being derived from successive reductions and oxidations of the working solution, in which process the working solution is placed in contact with alumina, the said alumina being obtained from a shaping operation by coagulation into drops or by extrusion.
REFERENCES:
patent: 3565581 (1971-02-01), Lee et al.
patent: 3912766 (1975-10-01), Logan et al.
patent: 4566998 (1986-01-01), Ochoa et al.
Le Loarer Jean-Luc
Nedez Christophe
Taxil Bernard
Dees Jos,e G.
Procatalyse S.A.
Pryor Alton
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