Production of phenol

Details Production of phenol Production of phenol

1999-04-22

2001-01-02

Padmanabhan, Sreeni (Department: 1621)

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

Organic compounds

Oxygen containing

C568S385000, C568S485000, C568S741000, C568S754000, C568S768000

Utility Patent

active

06169216

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the production of phenol and more particularly to a process for producing phenol and acetone from cumene hydroperoxide.
2. Description of the Prior Art
Phenol is an important organic chemical with a wide variety of industrial uses. It is used, for example, in the production of phenolic resins, bisphenol-A and caprolactam. A number of processes are currently in use for the production of phenol but the single process providing the largest proportion of the total production capacity is the cumene process which now accounts for over three quarters of the total U.S. production. The basic reaction involved in this process is the cleavage of cumene hydroperoxide into phenol and acetone:
C
6
H
5
C(CH
3
)
2
OOH=C
6
H
5
OH+(CH
3
)
2
CO
On the industrial scale, the cumene hydroperoxide is usually treated with dilute sulphuric acid (5 to 25 percent concentration) at a temperature of about 50° to 70° C. After the cleavage is complete, the reaction mixture is separated and the oil layer distilled to obtain the phenol and acetone together with cumene, alpha-methylstyrene, acetophenone and tars. The cumene may be recycled for conversion to the hydroperoxide and subsequent cleavage. The phenol produced in this way is suitable for use in resins although further purification is required for a pharmaceutical grade product.
Although the process described above is capable of producing both phenol and acetone in good yields, it would be desirable to find a process which would reduce the need for the product separation and purification steps which are inherent in a homogeneous process and would avoid the need for environmentally hazardous liquid acids.
The heterogeneous cleavage of cumene hydroperoxide (CHP) over various solid acid catalysts has already been reported. For example, U.S. Pat. No. 4,490,565 discloses the use of zeolite beta in the cleavage of cumene hydroperoxide, whereas U.S. Pat. No. 4,490,566 discloses the use of a Constraint Index 1-12 zeolite, such as ZSM-5, in the same process.
U.S. Pat. No. 4,898,995 discloses a process for the coproduction of phenol and acetone by reacting cumene hydroperoxide over a heterogeneous catalyst consisting essentially of a heteropoly acid, such as 12-tungstophosphoric acid, on an inert support, such as silica, alumina, titania and zirconia. Such heteropoly acid catalysts are inherently unstable at temperatures in excess of 350° C.
None of the solid-acid catalysts currently proposed for cumene hydroperoxide cleavage exhibit the required combination of activity and selectivity to provide an acceptable replacement for sulfuric acid.
SUMMARY OF THE INVENTION
The present invention is directed to a process for producing phenol and acetone from cumene hydroperoxide, wherein the process comprises the step of contacting cumene hydroperoxide with a solid-acid catalyst comprising a sulfated transition metal oxide.
The process of the invention can achieve significant conversion of cumene hydroperoxide to phenol and acetone with low coproduction of impurities such as 4-cumylphenol, mesityl oxide and diacetone alcohol.
Preferably, the transition metal oxide includes at least one metal oxide selected from Groups IVB, IVA, VIIB and VIII of the Periodic Table.
Preferably, the transition metal oxide includes zirconia and more preferably includes zirconia together with an oxide of iron or oxides of iron and manganese.
Preferably, the sulfated transition metal oxide is calcined at a temperature of at least 400° C. and more preferably at least 500° C.
Preferably, said contacting step is conducted at a temperature of 20 to 150° C. and a pressure of atmospheric to 1000 psig and more preferably at a temperature of 40 to 120° C. and a pressure of atmospheric to 400 psig.
DESCRIPTION OF SPECIFIC EMBODIMENTS
It is known from, for example, the article by M. Hino et al in
Journal of the American Chemical Society,
Oct. 10, 1979, pages 6439-41, that solid acid catalysts useful for butane isomerization can be prepared by treating zirconia with sulfate ions and calcining the product. According to the invention, it has been found that a solid acid catalyst comprising a sulfated transition metal oxide, particularly a Group IVB metal oxide, such as zirconia, is an active and selective catalyst for the cleavage of cumene hydroperoxide.
The transition metal oxide used in the catalyst of the invention preferably includes at least one oxide of a Group IVB (Group 4 in the Group 1-18 classification system recommended by IUPAC) metal, such as titania or zirconia, a Group IVA (Group 14 in the Group 1-18 classification system recommended by IUPAC) metal, such as tin oxide, a Group VIIB (Group 7 in the Group 1-18 classification system recommended by IUPAC) metal, such as manganese oxide, and/or a Group VIII (Group 8 in the Group 1-18 classification system recommended by IUPAC) metal, such as iron oxide. Most preferably, the transition metal oxide includes zirconia. The catalyst of the invention may comprise more than one transition metal oxide, preferably a combination of zirconium and iron oxides or a combination of iron, manganese and zirconium oxides. The mixed transition metal oxide may be prepared by techniques known in the art, such as impregnation, coimpregnation, coprecipitation, physical admixture, etc.
The transition metal oxide is sulfated by treatment with a source of sulfate ion, such as sulfuric acid or, more preferably, ammonium sulfate. It is also possible to treat the transition metal oxide with a compound capable of forming sulfate ions on calcination, such as hydrogen sulfide, sulfur dioxide or mercaptans.
The catalyst used in the process of the invention preferably contains 0.5 to 20%, and more preferably 5 to 15%, of sulfate ion by weight of the catalyst.
After treatment with the source of sulfate ion, the transition metal oxide catalyst is calcined at a temperature of at least 400° C. and more preferably at least 500° C., typically from 500 to 800° C., for a period of 2 to 30 hours.
The cleavage reaction of the invention is effected by contacting the cumene hydroperoxide with the solid acid catalyst described above in the liquid phase at a temperature of 20 to 150° C., preferably 40 to 120° C., a pressure of atmospheric to 1000 psig, preferably atmospheric to 400 psig. To effect the contacting of the cumene hydroperoxide, the solid acid catalyst described above may be contained in a stationary or fluidized bed, and the contacting operation may take place continuously or batch-wise. If the contacting takes place continuously, the LHSV based on cumene hydroperoxide is within the range of 0.1 to 100 hr
−1
, preferably 1 to 50 hr
−1
. If the contacting takes place batch-wise, the residence time is within the range of 1 to 360 min, preferably 1 to 180 min. The cumene hydroperoxide is preferably dissolved in an organic solvent inert to the cleavage reaction, such as benzene, toluene, acetone and most preferably acetone. The use of a solvent is preferred so as assist in dissipating the heat of reaction (about 60 kcal/mol).


REFERENCES:
patent: 4490565 (1984-12-01), Chang et al.
patent: 4490566 (1984-12-01), Chang et al.
patent: 4898995 (1990-02-01), Knifton et al.
M. Hino et al.,Journal of the American Chemical Society, Oct. 10, 1979, pp. 6439-6441.

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