Process for preparing cyclohexanol and cyclohexanone

Details Process for preparing cyclohexanol and cyclohexanone Process for preparing cyclohexanol and cyclohexanone

1998-09-01

2000-06-13

Gitomer, Ralph

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

502326, C07C 3508, B01J 2344

Patent

active

060751703

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to a process for preparing cyclohexanol and cyclohexanone, in particular, to a process for preparing cyclohexanol and cyclohexanone by selectively oxidizing cyclohexane with Fe/Pd catalyst in a flow of hydrogen and oxygen gases in the mixture of acetone and acetic acid.
Cyclohexanol and cyclohexanone are available as intermediates for synthesizing nylon-6 and nylon-6,6 and generally produced by oxidation of cyclohexane on an industrial scale. But the conventional processes of preparing cyclohexanol and cyclohexanone have some deficiencies that these processes require a condition of high temperature over 150.degree. C. and high pressure over 8 atm and its conversion is as low as 4%. Further, the product selectivity cannot exceed 80% because various decomposed oxidation-products of cyclohexane are produced from these reactions.
Because of the above problems, continuous researches on more effective and selective processes for preparing cyclohexanol and cyclohexanone have been conducted. For example, European patent appln. No. 83-87,924 discloses a process for preparing alcohol or ketones by oxidizing parraffinic hydrocarbons in a reaction system which employs iron catalyst, hydrogen sulfide, acetic acid, pyridine solvent and oxygen. But the resulting mixture shows poor separation and recovery of catalyst and products and especially, a large amount of pyridine is used compared to the amount of reaction product. Therefore, the problems of economical deficience and toxicity were raised.
As another example, in Japanese patent unexamined publication 85-92,236, cyclohexanone was acquired by adding oxygen to cyclohexene but there remains a problem that the manufacture of cyclohexene is more difficult that that of cyclohexane.
Additionally, the inventors of this invention discloses in U.S. Pat. No. 5,208,392 a method for preparing cyclohexanol and cyclohexanone with about 3.about.7% yields with no byproducts, by the oxidation of cyclohexane in hydrogen and oxygen gases with Fe/Pd catalyst in acetone solvent.
This invention is an improvement of U.S. Pat. No. 5,208,392 in that the activity and the stability of catalyst are improved through ligand binding with iron catalyst by using the solvent mixture of acetone and acetic acid instead of pure acetone solvent. As the result, yields of cyclohexanol and cyclohexanone increased significantly compared with those of U.S. Pat. No. 5,208,392. And especially, the more reaction time is extended and the more yields increase greatly up to about 4.about.12% because the deactiviation of catalyst is reduced. Moreover, there is little or nothing of byproducts during the oxidation of cyclohexane and the recovering and reusing of solid Fe/Pd catalyst is very easy.


SUMMARY OF THE INVENTION

The object of this invention is to provide a new process for preparing cyclohexanol and cyclohexanone with high yields. parts) and acetic acid (0.05.about.1.5 weight parts) in preparing cyclohexanol and cyclohexanone by oxidation of cyclohexane with Fe/Pd catalyst.


DETAILED DESCRIPTION OF THIS INVENTION

This invention is based on the catalytic abilities, that is, that of palladium catalyst is to convert molecular hydrogen and oxygen added to the solvent into hydrogen peroxide; and that of iron catalyst is to use the said hydrogen peroxide in the oxidation of hydrocarbons and it is characterized in using the mixture of acetone and acetic acid as a solvent. The said acetic acid acts as a ligand for iron catalyst and plays a role to improve the activity and the stability of iron catalyst.
In this invention, iron and palladium are used as catalysts and they can be used respectively or properly mixed together as solid catalysts.
The iron catalyst of this invention employs iron salt such as Fe.sup.2+ or Fe.sup.3+, or iron oxide such as FeCl.sub.2, FeCl.sub.3, FeO, Fe.sub.2 O.sub.3, FeSO.sub.4, Fe.sub.2 (SO.sub.4).sub.3 or Fe(OAc).sub.2 with no special pretreatment. And the palladium catalyst of this invention employs palladi

REFERENCES:
patent: 5208392 (1993-05-01), Lee et al.
Jun et al. Hydroxylation of cyclohexane with hydrogen and oxygen in acetone and silica-supported iron-palladium catalysts. Chem.-ing.-Tech. 64 (7), pp. 637-639. Abstract only. (1992) No. month found.

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