CA1064007A

CA1064007A - Process for preparing cyclohexanone

Info

Publication number: CA1064007A
Application number: CA246,294A
Authority: CA
Inventors: Magdy Nicola; Richard Sailer; Bruno Frischknecht
Original assignee: Inventa AG fuer Forschung und Patentverwertung
Current assignee: Inventa AG fuer Forschung und Patentverwertung
Priority date: 1975-02-20
Filing date: 1976-02-19
Publication date: 1979-10-09
Also published as: FR2301506A1; DE2606489A1; CH594585A5; DE2606489C3; FR2301506B1; ES445266A1; IN142090B; DE2606489B2; GB1471854A

Abstract

ABSTRACT OF DISCLOSURE

A process is disclosed for the production of cyclohexanone by hydrogenation of phenol in the presence of catalyst containing platinum metal. The support for the catalyst comprises a mixture of an alkaline-earth carbonate and an alkaline-earth hydrogen phosphate.

Description

The object of this inven~ion is to provide a catalyst or the production o~ cyclohexanone by ~he hydrogenation of phenol which is high in activity and selectivity. A platinum metal catalyst having as a support a mixture o~ an alkaline-earth carbonate and an alkaline-earth hydrogen phosphate accom-plishes the object of the present invention.
The prior art discloses a process for the production of cyclohexanone wherein a special quality phenol is hydrogenated in the liquid phase and in the presence of a palladium/activated carbon catalyst utilizing sodium as a promoter (German laid-open Patent Speoi~ication 1,144,262). The disadvan~ages of this process are two-fold. First, the preparation of the catalyst containing the promoter involves a complicated ancl costly procedure. Further, this process involves the use of a special quality phenol which additionally adds to the cost of the J operation.
,~, German~Laid~open Patent Specification 1,124,487 teaches the hydrogenation o phenol in the gaseous phase utilizing a . . .
25 palladium/aluminum oxide catalyst. However, this process is :! 1 :;1 l .

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unsatis~actory due to the ~msatisfactory conversion rate of phenol to cyclohexanone which is a direct result of the relatively low catalyst activity. In addition, a high proportion of undesired cyclohexanol is obtained as a by-product According to another known process (Swiss Patent Specification 463,493) phenol is hydrogenated in the trickling phase in the presence of a palladium/aluminum catalyst.

In addition, German laid-open Patent Specification .~ .
1,298,098) discloses the hydrogenation of phenol in the gaseous phase in the presence of a palladium catalyst. The cata~yst support consists of aluminum oxide and an alkaline-earth ; hydroxide.
Finally, aluminum spindels are used as a support for a palladium catalyst in the process for hydrogenating phenol ;a8 disclosed in German laid-open Pending Patent application

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The previously mentioned processes ~uffer from the same disadvantage; namely~ a relatively low activity of the 20;~ catalyst. In fact, the activity of the catalyst is directly ~`
` related to the amount of catalyQt andthe size of the apparatus j~
emplo~ed. Thereore, a low activity catalyst impalrs the ~i.
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; economic desirability of the process.

It is with knowledge of these disadvantages ~hat the ~ present inve~tor sought a catalyst having a high ac~ivi~y and ~electivity for the production of cyclohexanorle by the ~ hydrogenation of p~enol.

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Surprisingly, i~ was discovered that cyclohexanone is produced with high selec~ivity in the presence of a greatly active platinum metal catalyst having as a support a mixture of alkaline-earth carbonate and alkaline-earth hydrogen phosphate.
Particularly suitable as ~he platinum metal is palladium. The process may be performed either in the - liquid phase or in the gaseous or trickling phase which is preferred.
~0 While in the liquid phase the catalyst is employed in the form of a powder. However, in the gaseous phase, the catalyst must first be molded. For example, the catalyst . . .
~ can be pressed into tablets, briquettes or pelle~s. This is . ~ : .. .
made possible by the presence of the alkalin~-earth hydrogen ~;15 phosphate. If desired, the ability of the catalyst to be molded can be enha~ced by the addition of such known aids m as graphite or polyvinyl alcohol.
In the gaseous phase the molar ratio of hydrogen to phenol is 3:1 to 50:1 and particularly preferred is a .
~20 ~ molar ratio of 5:1 to 30:1. In this process it is possible to employ a mixture of hydrogen with an i~ert gas. Nitrogen ~ is an example o~ such an inert gas. Further, prior to com-

3~ meneing hydrogena~ion in the gaseous phase, it is preferable ~.!
to activate the catalyst with hydrogen. Finally, the ca~alys~
~25 ~; ~ can be loaded at a rate of 1-3 kg phenol per liter of catalyst per hour.
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`~ - 3 - ~-~06~0C~7 Generally it i9 preferrecl that the reaction temperature be between about 110C to 250C. The particularly preEerred temperature range ls 120C. to 220C.
The pressure of the reaction is not cr-itical and the desired objects of the invention can be achieved by emplo~ing standard pressure or pressures higher or lower than standard pressure.
The catalyst preferably con~ains 0.1-10% of platinum metal based on the total weight of the catalyst.
The particularly preferred platinum metal content is 1-5%.
All carbonates of the alkaline-earth metals may - be employed as the carbonate constituent of the catalyst support. Particularly desirable results are obtained with calcium carbonate. Particularly preferred is a calcium lS carbonate w~ich is obtained by the precipitation of water- -: soluble calcium salt~ with water soluble carbonates. The ~: `
preferred calcium carbonate is preferably prepared by : mixing. 5-2~/Oaqueous solutions of calcium chloride and sodium carbonate at 50-90C and separating the precipatated .~, .
20 ~ calcium carbonate from the solution. It is also possible to use commercially available calcium carbonates as the a~kaline-earth carbonate constituent of the catalyst support.
The alkaline-earth hydrogen phosphate, in particular calcium hydrogen phosphate, is preerably added to ~he alkaline-~25~ eart~ carbonate before addi~;ion of ~he palladium. The amount of~cal~iu~ hydrogen~ phosphate is preferably 10-30% by weight o ~the total weight o~ the catalyst support.
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The preparation o~ the pallaclium ca~alyst accordLng to the present invention is advantageously effected by ~irst mi~ing calcium carbonate with the desired amount of calcium hydrogen phosphate and then forming a suspension with a palladium chloride solution. The thus formed suspension is reduced with an alkaline formaldehyde solution or hydrogen, preferably at 40C, After separation from the aqueous phase, the catalyst is washed and dryed and ~hen can be employed directly for the hydrogenation of phenol in the liquid phase to produce cyclohexanone, If the gaseous phase is desired the catalyst ~ must first be molded as described previously.
; The following examples are recited for descriptive purposes only and are not meant in anyway to limit the scope ,.~
~ of the present invention.
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1~ Exam~le 1 , ~ :
~ a) 3,600 parts by volume of a 20% calcium chloride , . .
solution are added at 90C while st;rring to 6,890 parts by volume of a 10% sodium carbonate solution. After cooling, the calcium carbonate formed is filtered off and washed with water ~, '~20~ until chloride ions can not be detected. Finally, the ; calcium carbonate is dried at 130C in a vacuum drying chamber.
b)~ 400 par~s by weighe o~ the thus obtained calcium c arbonate are mixed with 100 g of calcium hydrogen phosphate ~ and stirred together a~ 40C with 29250 parts by volume of 1~2~ a solution containing 2% of palladium in the form of palladium ; chloride to form a suspension. After a short time, prac~icall~

all the palladium chloride has been absorbed on the supportO

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~L~64~;)7 A mixture of 370 parts by volume of 4% sodium hydroxide solution and 180 parts by volume of 40% formaldehyde solution i5 then added slowly while stirring continously.
The reduced catalyst is filtered off, washed with water until chloride ions cannot be detected and then dried at 130C in vacuo.
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The catalyst contains 5~ of palladium. After admixing 2% of graphite and 0.5% of polyvinyl alcohol with the powder, it is pressed into tablets with a diameter of `- 10 5 mm and a thickness of 3 - 5 mm.
c) 274 g of these catalyst tablets are put into a heatable reaction tube. Prior to the hydrogenation, the catalyst is treated with hydrogen for 1 hour at 120C. 720 g of vaporized phenol, together with 2,400 liters per hour of hydrogen are then passed over the catalyst at a heating or cooling temperature of 120 C and at a pressure of 0.1 atmos-`1 pheres.

;,., The amount of phenol corresponds to a catalyst load of 26 g phenol/g catalyst/hour. The hydrogenation product ~ 20 contains only 3.6% o phenol. In addition to 92.3% of :, ~ cyclohexanone, there is produced 4.1~ of cyclohexanol.
,J ~ Example 2 ~:
' With the hydrogenation apparatus and the catalyst : according to Example 1,696 g of vaporized phenol, together ;~ 25 with 3,700 liters per hour of hydrogen, are passed over the -~ catalyst at a heating temperature of 120C. This corresponds ~ to a load of 2.5 g phenol/g catalyst/hours.
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In addition to 6.2% o unconverted phenol, the hydrogenation produc~ contains 90.7% of cyclohexanone and 3.1% of cyclohexanol~
Example 3

5' C 400 g of precipitated "Fluka" calcium carbonate and 100 g of calcium hydrogen phosphate are mixed and catalyst tablets are produced therefrom as detailed in Example lb.
240 g of this catalyst are placed in a reaction tube in accordance with Example lc. The tube is heated to 140 C and the ca~alyst is treated with hydrogen for 1 hour.
Thereafter, 750 g of vaporized phenol, together with 1,200 liters per hour of hydrogen, are passed over the catalyst at a heating temperature of 120C. This corresonds to a catalyst load of 3.1 g phenol/g catalyst/hour.
The hydrogenation product is composed of 92.5~ of cyclohexanone, 3.1% of cyclohexanol, 1.2% of other by-products and 3.2% of unconverted pheno~.
Example 4 The hydrogenation appaxatus and catalyst according to Example 1 are used.
398 g of phenol per hour are trickled over the catalyst at a heating temperature of 120C. At the same time, 500 1iters per hour of hydrogen are passed over the catalyst.
The catalyst load is 1.45 g phenol/g catalyst/hour.
2.4% of unconverted phenol is found in the reaction product. Moreover, 91.4% of cyclohexanone and 6.2~ of by-products, chiefly cyclohexanol, are contained therein.

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Example 5 The catalyst is prepared in accordance with Example la and lb, except that only 1125 parts by volume of palladium chloride solution are employed.
The finished catalyst contains 2.5~ of palladium.
285 g of the catalyst tablets obtained are put into a heatable reaction tube. Prior to the hydrogenation, the catalyst is treated with hydrogen for 3 hours at 120C, 300 g of vaporized phenol, together with 500 liters per hour of hydrogen, are then passed over the catalyst at a heating temperature of 130C and at a pressure of 0.2 atmospheres.
The amount of phenol corresponds to a catalyst load of 1.05 g catalyst/hour. The hydrogenation product contains, in addition to 1.4~ of unconverted phenol, 97.2% of cyclohexanone and 1.4% of cyclohexanol.

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Claims

WHAT IS CLAIMED IS:

1, In a process for the production of cyclohexanone by the hydrogenation of phenol in the presence of a supported platinum metal catalyst, the improvement comprising the steps of forming a mixture of an alkaline - earth carbonate and an alkaline earth hydrogen phosphate and employing said mixture as the catalyst support.

2. The process of claim 1 wherein said platinum metal catalyst is palladium.

3. The process of claim 1 wherein said catalyst contains 0.1 - 10%
of platinum metal.

4. The process of claim 3 wherein said catalyst contains 1-5%
platinum metal.

5. The process of claim 1 wherein said alkaline earth carbonate is calcium carbonate.

6. The process of claim 5 further comprising the steps of:
a) mixing 5-20% aqueous solutions of calcium chloride and sodium carbonate at 50-90°C, b) precipitating said calcium carbonate from said mixture, c) separating said calcium carbonate from said mixture, and d) mixing the calcium carbonate thus obtained with said alkaline earth hydrogen phosphate.

7. The process of claim 1 wherein said alkaline-earth hydrogen phosphate is calcium hydrogen phosphate.

8. The process of claim 7 wherein said calcium hydrogen phosphate is 10-30% by weight of the total weight of the catalyst support.

9. The process of claim 1 wherein the said alkaline-earth hydrogen phosphate is first added to said alkaline-earth carbonate and then said platinum metal is contacted to the support thus formed.

10. A catalyst support for use in a process of hydrogenating phenol comprising a mixture of an alkaline earth carbonate and an alkaline earth hydrogen phosphate.

11. The catalyst support of claim 10 wherein the alkaline earth carbonate is calcium carbonate.

12. The catalyst support of claim 10 wherein the alkaline earth hydrogen phosphate is calcium hydrogen phosphate.

13. The catalyst support of claim 10 wherein said alkaline earth hydrogen phosphate is present in an amount of between about 10%
and 30% based on the total weight of the catalyst support.

14. A process for the production of cyclohexanone by the hydrogenation of phenol in the presence of a platinum metal catalyst, having as a support a mixture of an alkaline-earth carbonate and an alkaline-earth hydrogen phosphate, said process comprising;
a) adding said mixture of an alkaline-earth carbonate and an alkaline earth hydrogen phosphate to a platinum metal chloride solution to form an aqueous suspension, b) reducing said suspension with a member selected from the group consisting of an alkaline formaldehyde solution and hydrogen gas, c) recovering said catalyst from said suspension, d) washing and drying said catalyst, e) adding said catalyst to phenol, and f) hydrogenating said phenol in the presence of said catalyst,

15. The process of claim 14 wherein said hydrogenation is performed at a temperature of between about 110°-250°C.

16. The process of claim 14 wherein said platinum metal is palladium.

17. The process of claim 14 wherein said alkaline earth carbonate is calcium carbonate.

18. The process of claim 14 wherein said alkaline earth hydrogen phosphate is calcium hydrogen phosphate.

19. The process of claim 14 further comprising the step of adding said catalyst to phenol in the gaseous phase, and maintaining said phenol in the gaseous phase during hydrogenation.

20. The process of claim 19 wherein the molar ratio of hydrogen to phenol is between about 3:1 and 50:1.

21. The process of claim 20 wherein said molar ratio is between about 5:1 and 30:1.

22. The process of claim 19 wherein said catalyst recovered from suspension is in powder form.

23. The process of claim 22 wherein the powder catalyst is agglomerated and molded before the recovered catalyst is added to said phenol.

24. The process of claim 23 wherein a compound selected from the group consisting of graphite or polyvinyl alcohol is added to said catalyst.

25. The process of claim 19 wherein said recovered catalyst is activated with hydrogen prior to the addition of said recovered catalyst to said phenol.

26. The process of claim 19 wherein hydrogen gas is admixed with an inert gas and then added to the mixture of said recovered catalyst and phenol.

27. The process of claim 26 wherein said inert gas is nitrogen.

28. The process of claim 14 wherein said hydrogenation is continuous.

29. The process of claim 28 wherein 1-3 kg of phenol are used per liter of recovered catalyst per hour.

30. The process of claim 14 wherein said phenol is in the liquid phase and wherein the hydrogenation reaction is carried out while maintaining said phenol in the liquid phase.