DE2025726A1 - Cyclohexanone prodn - by hydrogenation of phenol in the - presence of a promoted palladium catalyst - Google Patents

Abstract

Cyclohexanone is produced by hydrogenation of phenol in the vapour phase with a Pd catalyst in which the Pd is present as a thin layer (is not 0.3 mm) in quantities of 0.3-1.0 wt. % on a carrier which contains an alkali metal carbonate in quantities of 3-10 wt. % and the hydrogenation is effected at 100-150 degrees C with a throughput of phenol of 1-2 wt. pts. per wt. pt. catalyst per hr. at a mole ratio of hydrogen to phenol of 3-10 and at a press is not >2 atm. The method gives a high yield up to 99 wt. % and has high selectivity.

Description

Description of the patent application by Grigorij Davidowitsch Ljubarskij, Chemist, Moscow, USSR Margarita Michailowna Streletz, chemist, Moscow, USSR Wazlaw Aleksandrovich Sokolsky, chemist, Moscow, USSR on PROCEDURES FOR THE PREPARATION OF CYCLOHEXANONE The present invention relates to the Field of hydrogenation of organic compounds, in particular the process for Production of cyclohexanone by hydrogenation of phenol. Cyclohexanone is an intermediate for the production of polyamide fibers.

A number of patents are known in this field, Zum Example, U.S. Patent Nos. 2829166, 2857432, 2873296, 3076810, British Patent No. 890095, Dutch Patent No. 101701, French Patent specification No. 1467482, patent specification of the GDR No. 51635, the Czechoslovakia No. 123285, copyright of the USSR No.

168282. In the patents listed are processes of hydrogenation of phenol on the palladium catalyst, including the hydrogenation process of phenol in the vapor phase. These methods have the following disadvantages on: 1) Difficulty separating the catalyst powder from the target product in the case of sump phase hydrogenation of phenol; 2) fairly high palladium content (usually about 5 wt.%) In the most catalysts; 3. Low process performance, those with low activity the catalysts to be used; 4) Complexity of manufacturing of catalysts; 5) low selectivity, based on the cyclohexanone, in particular in vapor phase hydrogenation It is an object of the present invention to eliminate a mentioned disadvantages.

In accordance with the goal, the task was set to be a highly productive Process of vapor phase hydrogenation of phenol over a palladium catalyst, which is a having high activity and selectivity.

The problem posed was achieved by a process that was geinaß the invention consists in that one phenol on Supported catalyst hydrogenated, in which palladium in a thin layer not more than 0.3 mm thick in an amount of 0.3 to 1.0 wt.% Is applied to the carrier and the one promoter carbonate of an alkali metal in an amount of 3-10% by weight. The hydrogenation is at a temperature of 100-150 ° C with the passage rate of the phenol 1-2 parts by weight 1 part by weight of catalyst per 1 hour at a molecular ratio of hydrogen to phenol from 3 to 10 and a pressure of at most 2 atm.

The hydrogenation on a granulated palladium catalyst is recommended, in the palladium in a layer 0.1 - Ω, 2 mm thick on the γ-alumina support is applied to perform. Such a catalyst is made by impregnating -Aluminium oxide obtained with aqueous palladium chloride solution at a pH of 1-3. The hydrogenation in the presence of said catalyst is characterized by a high Effectiveness. Other carriers can also be used, for example silica gel or charcoal be used.

The alkali metal carbonate content of the palladium catalyst, e.g. Sodium carbonate, is preferably 4-6% by weight.

You can hydrogenate phenol on the palladium catalyst, the other than the promoter still contains inhibitor. Compounds of the elements of III.B - VI.B groups of the periodic table in kenbren of 0.5 - 5 atom%, based on palladium lot, used.

Compliance with the technological process conditions mentioned in the hydrogenation of phenol guarantees a performance and selectivity of the catalyst, pickling on the cyclohexagon, up to 99% by weight.

Increase in the reaction temperature, which is above the stated, is undesirable because it increases the amount of cyclohexanone that is formed, i.e. leads to a reduction in selectivity; the same will happen with pressure increase and Reduction in the rate of passage of the phenol through the catalyst layer was observed.

The increase in the said thickness of the palladium layer on the Carrier leads to the diffusion inhibition of the process, i.e. to a reduction in the catalyst performance.

The hydrogenation process of phenol is a sequence of two reactions: a) hydrogenation of phenol in ketone - cyclohexanone and b) subsequent hydrogenation of cyclohexanone in alcohol - cyclohexanol.

1st stage Ile stage related to a high selectivity of the process on the To achieve cyclohexanone, one must be sufficiently active Have catalyst which mainly causes the course of the first reaction stage, but is weakly active in relation to the second mare. To the process with high Performance (with high load, based on the phenol), may the reaction speed in the first stage is not inhibited by diffusion processes what aa large granules of the catalyst is usually difficult to achieve.

We have found that by applying palladium to the Granules of the carrier in a thin layer, as described above, have the effect Eliminate the diffusion inhibition and thereby a higher activity and at the same time Increased selectivity can be achieved because the reaction product is carried away quickly the 1st stage (ketone) from the catalyst without it being held in the pores of the catalyst its degree of treatment is reduced after the 2nd stage (in alcohol).

The rate of the 1st stage of hydrogenation aa our palladium catalyst is 10-15 times as high as that of the II.

Stage, whereby a high selectivity of the process is required.

We have found that it can increase the activity time of the catalyst is sufficient for the given process, the said amount of palladium from 0.3 to 1.0 % By weight on a carrier, for example γ-aluminum oxide, in a thin layer by impregnating the carrier with an aqueous solution of the palladium salt. The depth of penetration of the palladium solution into the t'-alumina granules can be regulated by varying the pH values of this solution: the higher the pH value represents palladium chloride solution to be used for impregnation of γ -aluminium oxide granulate is, the smaller the watering depth, i.e. the thinner it is on the The active palladium layer forming the surface of the granulate and consequently the less is the probability that the rate of hydrogenation of phenol is inhibited will.

It turned out that the optimal depth of impregnation of the granules O is 0.1-0.2 mm, which is achieved by using palladium chloride solutions with pH values 1.5-3 is reached. In the attached table information is given, the changes in layer thicknesses and activity of the with different impregnation conditions Varying the pH values of the solution show the catalyst pattern obtained: Thickness of the active activity (percentage of pH value layer, mm of conversion) 0.14 1.9 55 0.54 1.2 67 1.66 0.2 95 3.16 0.12 96 Adding promoters to Example soda, to which the catalyst enables a well-developed palladium surface, i.e. to obtain a finely dispersed state of the active component; the size of the Palladium surface is almost doubled in the process.

Finally, to speed up the secondary reaction of hydrogenation By suppressing cyclohexanone, the catalyst will be micro-amounts of catalytic Poison inhibitors added chemically from the most active points of the catalyst are sorbed and thereby block them. It is found that as inhibitors Compounds of the elements of the I1I.B - VI.B groups of the periodic table e.g.

Sulfur compounds, mercury, cadmium, lead and others in the form of soluble salts or organic compounds can be used.

The technological conditions discussed above, namely: Compliance a certain pH value of the palladium salt solution when the carrier is soaked, treatment of the catalyst with alkali metal carbonate, for example with soda, Sin Micro-amounts of inhibitors as well as performing the hydration process among the The above technological conditions made the activity and selectivity possible of the catalyst to increase and cyclohexanone in the hydrogenation of phenol with a high efficiency of 1-2 kg / h per 1 kg of catalyst and selectivity, based on the cyclohexanone, up to 99% can be obtained.

For a better understanding of the present invention, the following are made Examples of the specific implementation of the method are given.

Example 1.

100 ml of aqueous palladium chloride solution, the 0.5 g of palladium and 0.3 g of hydrochloric acid are gradually added with soda solution to a pH of 1.5 neutralized. With this solution 100 g of reprecipitated activated g -aluminium oxide, which is shaped as granules 4-5 mm in size, soaked; under these conditions the depth of the penetration of palladium into the granulate is about 0.15 mm. Moist granules are kept in the air for 12 hours, then at 1000C dried over the course of 8 hours and then with 80 ml of solution containing 5 g of soda, soaked. The granules dried at a temperature of 100-120 ° C in an amount of 20 g are introduced into a reaction tube and at 14,000 for 5 hours flushed with hydrogen at a rate of 100 l / h. This is the palladium oxide reduced to metallic palladium.

The catalyst obtained in this way gives 25 ml of phenol per hour in the form of vapors in a mixture with 50 l of hydrogen at 13,000 and Atmospheric pressure passed.

The reaction product contains 92% by weight of cyclohexanone and 5% by weight of cyclohexanol and 3% by weight residual phenol. The selectivity of the process, based on the ketene, is 93%.

Example 2.

This example shows the application of the catalyst pattern without treatment with soda.

100 g of r - aluminum oxide in the form of granules of 4x4 mm size with 100 ml of palladium chloride solution, which has a pH value of 1.6, and 0.5 g of palladium contains, soaked. The granulate is dried at 1200C within 6 hours and 20 g thereof are added to a reaction vessel through which hydrogen with a volume speed of 2000 h1bBi 1400 5 hours long. phenol is hydrogenated over this catalyst under the conditions described in Example 1. A product is obtained which contains 72% cyclohexanone, 10% cyclohexanol and 17% of the Reaction contains phenol # that has not occurred. So are activity and selectivity by the absence of promoter soda in the catalyst.

Example 3.

This example demonstrates the effect of the increased soda content.

The catalyst is according to the procedure described in Example 1 produced, only the soda content is 5% 15% increased been. When passing mixed phenol and hydrogen vapors through this catalyst under the conditions described in Example 1, the product obtained contains 78% cyclohexanone, 20.3% cyclohexanol, and 1.7% phenol; Selectivity is 78.5%. By lowering the test temperature to 120 ° C, a hydrogenation product was obtained, which contained 88% cyclohexanone, 10% cyclohexanol and 2% phenol; Selectivity scam about 88%. A substantial increase in the proportion of promoter in the catalyst is reduced which that s selectivity.

Example 4.

This example shows the effect of increased pressure on hydrogenation.

The catalyst described in Example 1 was hydrogenated by Phenol tested at a pressure of 15 at (instead of 1 at) and 1200C. The reaction product contained 72%.

Cyclohexanone, 26% cyclohexanol and about 2% residual phenol.

The selectivity was 74%. So, pressure increase with hydration of phenol leads to a reduction in the selective effect of the catalyst.

Example 5.

This example shows the effect of the reduced pH of the Palladium chloride solution on the activity of the catalyst.

100 g of γ-aluminum oxide in the form of granules are added 100 ml of aqueous palladium chloride solution containing 0.5 g of palladium and a pE value of 0.54 (instead of pH 1.5 according to Example 1), soaked. After treatment with 5% soda solution, the granules are dried at 100 ° C for 6 hours, the obtained catalyst in an amount of 20 g is introduced into the reaction vessel and flushed with hydrogen at 1400C for 5 hours to reduce the palladium. A vapor mixture of 20 g of phenol and 50 1 hydrogen per hour passed at 130 ° C. The reaction product contains 65% cyclohexanone, 2% cyclohexanol and 33% residual phenol, i.e. the activity of the catalyst greatly diminished. This shows the effect of the diffusion inhibition of the reaction; a the depth of the penetration of the palladium into the granulate is at pH value 0.54 1.2 mm instead of 0.1 - 0.2 mm at pH value 1.5-2).

Example 6.

The example shows the effect of treating the catalyst with Inhibitor.

The catalyst obtained according to Example 1 is with a solution of 40 mg of etching sublimate (inhibitor) in 80 ml of water and dried.

soaks. When passing mixed vapors of phenol and hydrogen through the layer of this catalyst is made under the conditions described in Example 1 obtain a product containing 97% cyclohexanone, 1% cyclohexanol and about 2% phenol. The selectivity is 99%.

Example 7.

The catalyst is prepared as described in Example 1, then he is treated with Ifihibitor. A solution of 10 mg of sodium sulfide is used as an inhibitor in 80 ml of water, which is 2.5 atom% sulfur, based on the palladium content in the catalyst is used.

When testing this catalyst under those described in Example 1 Conditions is obtained a product that contains 96.5% cyclohexanone and 1% cyclohexanol Contains 2.5% phenol. The selectivity is 99%.

The sodium sulfide can also be added to the soda solution when the catalyst is impregnated analogously to Example 1 are added.

From the examples 2, 3, 4, 5 cited it can be seen that the Reduction of the pH of the PdC12 solution below 1.5, absence of promoter or its content exceeding 10%, carrying out hydrogenation at elevated levels Pressures to reduce the activity and selectivity of the catalyst during hydrogenation leads. The temperature increase (above 1500C) and acts in the same direction reducing the rate of conduction of the phenol through the catalyst relative to the stated values.

Claims (4)

PATENT CLAIMS: 1. Process for the preparation of cyclohexanone by hydrogenation of Phenol in the vapor phase on the palladium catalyst, d u r c h e k e n n z e i c h n e t that the hydrogenation of phenol in the presence of catalyst in the palladium in a thin layer not more than 0.3 mm thick in an amount of 0.3 to 1.0 % By weight is applied to the carrier and which is an alkali metal carbonate in an amount of 3-10 wt.%, at a temperature of 100-1500C with passage rate of the phenol of 1-2 parts by weight of 1 part by weight of catalyst per hour at a molecular ratio from hydrogen to phenol from 3 to 1Q and a pressure not exceeding 2 at, is carried out. 2. The method according to claim 1, d a d u r c h g e k e n nz e i c h n e t that the hydrogenation of phenol on the falladium catalyst, in the palladium in a layer 0.1-0.2 mm thick on the γ aluminum oxide carrier, the is obtained by impregnating the same with palladium chloride solution with pH 1-3> is applied, performs. 3. The method of claim 1, 2, d a d u r c h g ek e n n z e i c hn e t that the hydrogenation of the phenol over the palladium catalyst, the 4-6 wt.% sodium carbonate contains. is carried out. 4. The method according to claim 1-3, d a d u r c h g ek e n n z e i o n e t that the hydrogenation of the phenol is carried out over a palladium catalyst, the inhibitor contains, and as an inhibitor compounds of the elements of III, B - VI.B Groups of the periodic table in the amounts of 0.5 - 5 atom%, based on the amount of palladium, be used.