DE2704345A1 - Methyl cyclohexanone prepd. by direct hydrogenation of cresol - using a platinum gp. metal catalyst pref. palladium on alkaline earth carbonate carrier - Google Patents

Abstract

Prepn. of methyl cyclohexanone by direct hydrogenation of cresol in presence of a catalyst of a Pt metal on a carrier of alkaline earth carbonate, opt. mixed with an alkaline earth hydrogen phosphate. Pref. hydrogenation is in gas or trickle phase, using the catalyst in the form of tablets, preforms or pellets. The catalyst consists of 1-5 wt.% Pd on a CaCO3 carrier made by mixing 5-20 wt.% solns. of caCl2 and Na2CO3 at 50-90 degrees C. A single-stage process is used, without intermediate prepn. of methyl cyclohexanol. The catalyst is more active and selective than the known Pd catalyst on carbon carrier, and large quantities of solvent are not required for the reaction.

Description

Process for the production of methylcyclohexanone

The present invention relates to a method for producing Methylcyclohexanone by hydrogenation of cresol in the presence of a platinum metal containing Catalyst.

It is common knowledge to hydrogenate methylcyclohexanone Cresol to methylcyclohexanol and subsequent dehydrogenation of the methylcyclohexanol to manufacture. This requires a two-stage procedure.

There is also a method (JA-PS 6 926 657), which in the presence of a Carbon / palladium catalyst cresol hydrogenated directly to methylcyclohexanone. disadvantage This process is that the hydrogenation in the presence of larger amounts of solvent is carried out.

The invention has the object by using a Catalyst with high activity and selectivity, the economy of the hydrogenation of the To increase cresol to methylcyclohexanone.

It was surprisingly found that cresol in the presence of platinum metal catalysts, the carrier of which is an alkaline earth carbonate or a mixture of alkaline earth carbonates and alkaline earth hydrogen phosphates, with very large Activity and high selectivity to methylcyclohexanone is hydrogenated.

The present invention is therefore a method for Production of methylcyclohexanone by hydrogenation of cresol in the presence of a Catalyst made from a platinum metal which is deposited on a carrier, which is characterized in that an alkaline earth carbonate is used as the catalyst support, optionally used in a mixture with an alkaline earth metal hydrogen phosphate.

Palladium is particularly suitable as the platinum metal. The procedure can in the liquid phase with a powdery catalyst or, preferably, in the gas or trickle phase are carried out, in the last two cases mentioned the catalyst is used in the form of tablets, tablets or pellets.

The cresol to be hydrogenated can be used either as a single o-, m- or p-isomer or as a mixture of two or all three isomers.

The hydrogen / cresol molar ratio to be used in the gas phase is preferably 3: 1 to 50: 1, in particular 5: 1 to 30: 1.

It is also possible, instead of pure hydrogen, to use a mixture of To use hydrogen with an inert gas such as nitrogen.

The reaction temperature is preferably 110 to 2500C, especially 120 to 2200C.

The process can be carried out either under normal pressure or under higher pressure or lower pressures.

The catalyst preferably contains 0.1 to 10%, in particular 1 up to 5%, platinum metal.

All carbonates can be used as the carbonate component of the catalyst support of the alkaline earth metal group can be used. Particularly good results are obtained with calcium carbonate. Calcium carbonate, which can be obtained by felling, is well suited obtained from water-soluble calcium salts with water-soluble carbonates.

It is preferably produced by using 5 to 20 dough aqueous Solutions of calcium chloride and sodium carbonate mixed at SO to 90 "C and that separating precipitated calcium carbonate. There are also commercially available calcium carbonates can be used as the carbonate component of the catalyst support.

Any other component of the catalyst support that may be present, the alkaline earth hydrogen phosphate, especially calcium hydrogen phosphate, becomes advantageous added to the carbonate prior to application of the palladium. The content of calcium hydrogen phosphate is advantageously 10 to 30, based on the total weight of the catalyst support.

The use of an alkaline earth metal hydrogen phosphate favors the Compressibility of the carrier material to form tablets, granules, etc.

The preparation of the palladium catalyst preferred according to the invention takes place in an advantageous manner that the catalyst support with a palladium chloride solution slurried and at preferably 40 "C with an alkaline formaldehyde solution or hydrogen is reduced. After separating the catalyst from the aqueous Phase and after washing and drying is the catalyst for the hydrogenation of Cresol to methylcyclohexanone can be used directly in the liquid phase. For hydrogenation In the gas or trickle phase, the catalyst powder has to be shaped beforehand, for example be compressed into tablets. If necessary, you can still check the compressibility by adding known auxiliaries such as graphite or polyvinyl alcohol. The catalyst must be activated before the hydrogenation in the gas phase begins recommended with hydrogen.

The catalysts obtained in the manner described can in the gas or trickle phase with 1 to 2 kg of cresol / liter of catalyst and hour are charged.

In the case of the hydrogenation in the liquid phase, the lead according to the invention to be used catalysts in a short time to high conversions.

The following examples illustrate the invention.

Example 1 a) 3,600 parts by volume of a 20 dough calcium chloride solution are added to 6,890 parts by volume of a 10% sodium carbonate solution at 900C Stir given. After cooling, the calcium carbonate formed is filtered off and washed with water until no more chloride ions can be detected. In the end is dried at 1300C in a vacuum drying cabinet.

b) 500 parts by weight of the calcium carbonate obtained are heated to 40.degree with 2 250 parts by volume of a solution containing 2% palladium in shape Contains of palladium chloride, stirred to a suspension.

After a short time, practically all of the palladium chloride is on the Carrier drawn up, Now a mixture of 370 parts by volume is added with constant stirring a 4% sodium hydroxide solution and 180 parts by volume of a 40% formaldehyde solution slowly admitted. The reduced catalyst is filtered off, washed with water, until no more chloride ions can be detected, and then dried at 130ob in a vacuum.

The catalyst contains 5% palladium. The powder becomes after admixture from 2% graphite and 0.5% polyvinyl alcohol to tablets of 5 mm in diameter and 3 to 4 mm high pressed.

c) 240 ml of these catalyst tablets are placed in a heatable reaction tube filled. Before the hydrogenation, the catalyst is hydrogenated for 1 hour at 1200C treated. Then at an on or cooling temperature of 1200C an hourly 360 g m-cresol as vapor together with 1000 l of hydrogen at a pressure of 0.1 atm given over the catalyst.

The cresol amount corresponds to a space velocity over the catalyst of 1.5 g cresol / ml Catalyst / hour, the hydrogenation product contains only 8.2% m-cresol. In addition to 87.5 t 3-methylcyclohexanone there is 4.3% 3-methylcycohexanol.

Example 2 With the hydrogenation device and the catalyst according to the example 1 are 348 g of p-cresol per hour as steam together with 900 g of hydrogen at a Heating temperature of 1200C passed over the catalyst. This corresponds to a burden of 1.45 9 cresol / ml catalyst / hour.

The hydrogenation product contains 7.1% unreacted p-cresol 90.1 % 4-methylcyclohexanone and 2.8% 4-methylcyclohexanol.

Example 3 With the hydrogenation device and the catalyst according to the example 1 are 250 g of o-cresol per hour as steam together with 800 liters of hydrogen at a Heating temperature of 1300C passed over the catalyst, this corresponds to a load of 1.04 g cresol / ml catalyst / hour.

The hydrogenation product contains 11.2% unreacted o-cresol 82.7% 2-methylcyclohexanone and 6.1% 2-methylcyclohexanol.

Example 4 With the hydrogenation device and the catalyst according to the example 1 380 g of a mixture of 65% m- and 35% p-cresol are used as steam every hour together with 1200 l of hydrogen at a heating temperature of 1200C over the catalyst directed. This corresponds to a loading of 1.58 g of cresol / ml of catalyst / hour.

The hydrogenation product contains 6.8% of unreacted cresol 88.9 t a mixture of 3- and 4-methylcyclohexanone and 4, § to a mixture of 3- and 4-methylcyclohexanol.

Example 5 400 g of calcium carbonate "Fluka" (Fluka AG, Buchs, Switzerland, precipitated) and 100 g calcium hydrogen phosphate are mixed. From the mixture will prepared according to the information in Example 1b) catalyst tablets.

250 ml of this catalyst are in a reaction tube according to the example 1 c) filled. It is heated to 1400C, whereupon the catalyst for 1 hour Hydrogen is treated. Thereafter, at a heating temperature of 1200C, every hour 420 g of m-cresol passed over the catalyst as vapor together with 1 200 1 of hydrogen. This corresponds to a space velocity over the catalyst of 1.8 g phenol / ml catalyst / hour.

The hydrogenation product is composed of 92.0% 3-methylcyclohexanone, 3.8% 3-methylcyclohexanol, 1.2% other by-products and 3.0 t unreacted Cresol.

Claims (5)

Claims to process for the production of methylcyclohexanone by hydrogenation of cresol in the presence of a platinum metal catalyst, which is deposited on a support, characterized in that it is used as a catalyst support an alkaline earth carbonate, optionally mixed with an alkaline earth hydrogen phosphate, used. 2. The method according to claim 1, characterized in that the Carries out hydrogenation in the gas or trickle phase. 3. The method according to claims 1 to 2, characterized in that that one uses catalysts which contain 1 to 5% palladium on the carrier. 4. The method according to claims 1 to 3, characterized in that that one uses a calcium carbonate, which by mixing 5 to 20% Solutions. of calcium chloride and sodium carbonate at 50 to 90 ° C is. 5. Catalyst made from a platinum metal deposited on a support is, characterized in that the catalyst support is made of an alkaline earth carbonate, optionally in a mixture with an alkaline earth metal hydrogen phosphate.