DE2107395A1 - Cyclohexanone prodn - by vapour-phase one-step hydrogenation of phenol using supported palladium catalyst - Google Patents

Abstract

One-step cyclohexanone prodn. is carried out in yields >95% and 100% conversion by passing phenol vapour and H2 or H2-contg. gas mixt., e.g. H2-N2 at 120-180 (140-170) degrees C through a catalyst bed prepd. by applying 0.1-1.2 (esp. 0.2-0.5) wt % Pd on a support contg. stable alkaline surface centres, pref. cation-exchange aluminosilicates, esp. zeolite-type molecular sieves. Phenol feed rate is 0.5-12 (1.5-5) mol/hr./g. Pd.

Description

Description of the patent application relating to METHOD OF MANUFACTURING OF CYCLOHEXANONE The invention relates to a process for the production of cyclohexanone from phenol, using a Pd catalyst.

It is known that cyclohexanone is produced by the hydrogenation of phenol can be. In the most widely used processes, phenol is converted into two reacton sachrittons converted into cyclohexanone. According to such a process that has been known for a long time in the first step phenol with 3 2048/4 ált. / Fné Molecules of hydrogen converted into cyclohexanol in a nickel catalyst, which after purification by distillation dehydrogenated to cyclohexanone at 400 to 500 ° C over zinc or iron catalysts will. The heat requirement of this step is significant. The raw products of the reaction are purified by distillation. The gross yield of cyclohexanone is 70 to 75% Ijis Patent No. 2,338,445 (1940); DRP No. 743 004 (1940) 1.

In addition to the low yield, this process has the further disadvantages that the reaction agar must be distilled twice and that the excess hydrogen must be increased significantly, which from the standpoint of the operating costs of the process is disadvantageous, or the space velocity must be reduced. what on the other hand a reduction in throughput capacity has the consequence to complete the exothermic To favor reduction of the phenol, Eq q are also only a one-step process Process for converting phenol into cyclohexanone is known.

According to one of these known processes, phenol becomes liquid under pressure Phase on a supported catalyst (5% palladium on activated charcoal partially to cyclohexanone hydrogenated.

This reaction gives only small yields and is not so industrial applied (U.S. Patent No. 2,829,166).

According to another known one-step process the hydrogenation runs in the gas phase over a supported aluminum oxide-palladium catalyst mixed with alkaline earth metal oxides away. Of the main disadvantages of this method, it should be mentioned that there is one requires large excess of hydrogen and that both the manufacture of the carrier as well as the activation of the catalytic converter and also the load capacity of the catalyst is relatively low [GDR patent no. 51 635 (1966)].

Soviet researchers have phenol on supported Al2O3 palladium catalysts hydrogenated with synthesis gas, the yield of cyclohexanone being 80% [Sikharanlidse and employees, Szobs Akad. Nauk Gras. SSR 43, 607 (1966); Sztrelec and coworkers, brains. Prom. No. 8, 7/567 / (196817.

The invention is based on the object of ensuring a method which while avoiding the disadvantages of the known solutions, the production of Cyclohexanone from phenol in a single step under atmospheric pressure and in allows good yield.

It has now been found that phenol in a single reaction step be converted into cyclohexanone with uptake of only 2 molecules of hydrogen If palladium is used as a catalyst, it can be converted to a stable alkaline Surface centers possessing carrier is applied.

It was also found that the loading capacity of the catalyst can be increased significantly when a combined catalyst bed is used or the bed of at least two catalyst layers with different Pd concentrations consists.

The invention relates to a process for the production of cyclohexanone from phenol, which consists of phenol vapors and hydrogen or hydrogen containing gas mixtures at 120 to 180 0C through the bed of a catalyst, the by applying 0.1 to 1.2 wt., preferably 0.2 to 0.5 wt. palladium produced on a support having stable alkaline surface centers was passed, the rate based on 1 g of palladium being the Phenol vapor feed 0.5 to 12 moles / hour, preferably 1.5 to 5.0 moles / hour. amounts to.

As a carrier with stable alkaline surface centers are preferred aluminosilicates capable of cation exchange are used. As for that purpose Molecular sieves of the zeolite type have proven to be very advantageous.

According to the invention it is expedient to proceed in such a way that phenol vapors in a 3 to 8-fold molar excess with Mixed hydrogen and then the resulting mixture at a temperature of -140 to 170 ° C over 0.2 to 0.5 wt .-% palladium-containing molecular sieve of the zeolite type is directed. The catalyst used in the process of the invention is preferably prepared in the following way: 100 g sodium aluminum hydrosilicate molecular sieve (Xlinosorb 4) are placed in a vacuum of 40 torr for two hours heated to 80 to 100 0C, and after suctioning off the carrier with a palladium salt solution, impregnated for example a palladium chloride solution. The palladium chloride solution is made by dissolving the corresponding amount of PdCl2 in 50 ml of a 0.5 N HCl solution manufactured; in the preparation of a catalyst containing 0.5% by weight of Pd 0.835 g (0.0C472 g mol) of PdC12 dissolved in 50 ml of 0.5 N HCl solution. After neutralization the product is washed with water.

The capacity of the catalytic converter can be increased significantly, ? v: hen there is a pre-treatment with corrugated surfaces prior to impregnation.

The grain diameters of the carrier are expediently between 1 mm and 7 mm. In reaction tubes of technical dimensions, a Catalyst used, which consists of a carrier with grain diameters of 3 to 5 mm was produced.

It is convenient to activate the catalyst in the reactor through which is used for the hydrogenation of the phenol.

Fig. 1 is the sketch of a for carrying out the invention Process-serving device, which is used in the implementation of the specified below Process examples was used.

In the device shown in FIG. 1, the gas components from the gas bottles 6 via pneumatic regulators not shown in the drawing and about the volume velocity the differential manometer measuring gas flows fed in.

The phenol is driven by a synchronous motor Piston pump 1, the delivery speed of which is 3 to 72 ml / hour. is dosed.

During the dosing, the phenol is emitted by the infrared heater 3 kept in the liquid state.

The gas stream and the phenol are in countercurrent in the with a Sheath provided evaporator 2 initiated. The mixture of gas and steam is continued from here into the reactor 4, which is also provided with a jacket. An ultra-thermostat circulates in the jackets of the evaporator and reactor 8 silicone oil heated to the appropriate temperature.

In the reactor, the gas mixture reaches the catalyst bed 9. The diameter of the catalyst bed is 22 mm, the height, depending on the amount of catalyst filled, 5 to 8 cm (in the case of 20 to 30 ml of catalyst).

The temperature of the catalyst bed is measured with an in the thermometer socket 7 located Fe-constantan thermocouple measured.

The reaction mixture is fed from the reactor into the cooler 5, where the liquid components condense.

The liquid that separates out in the cooler is subjected to gas chromatography using PEG on Celite as column filling and a thermal conductivity cell analyzed as a detector.

In the device described above, the catalyst is on the following Way activated.

20 to 30 ml of wet catalyst are introduced into the reactor 4. The reactor is heated to 130 ° C. while passing hydrogen through it. The temperature of the catalyst bed increases because of the water to be used for evaporation Heat of vaporization, only slowly from 40 at 70 ° C.

The reduction of the Pd compound goes into this temperature range in front of you what is noticeable through it.

that the surface turns gray or black. After the Temperature of 130 ° C, the reactor continues to be heated to 200 while flushing with hydrogen ° C and this temperature is kept constant for one hour. Afterward is cooled to the temperature at which the hydrogenation is carried out.

An argon-hydrogen mixture is then filtered at atmospheric pressure together with phenol vapor in a ratio of 10: 1 at 160 to 170 ° C into the reactor. Instead of argon, nitrogen can also be used.

The reactor is operated under the conditions given above for so long kept in operation until the amount of cyclohexanols in the reaction products less than 2; ol% decreased. Once such selectivity has been achieved, activation is complete of the catalyst has ended, the hydrogenation can now be carried out in a pure hydrogen atmosphere pass over.

In the method according to the invention, the service life of the Catalyst as well. The life of a catalyst containing 0.5% Pd was in such a manner that in the device described above for two months an average of 8 hours on each working day, the reaction on 30 ml of catalyst was allowed to play at 165 ° C., 0.113 mol of phenol and 28 l of hydrogen per hour (Molar ratio 1:10) were fed. The device was shut down with Hydrogen flushed through, the stress on the catalyst was reduced by the Heating up and cooling down once every working day, i.e. by approximately one 40 times special usage increased.

The conversion dropped from an initial 99.5% within the 2 months 95%, while constant values of about 96% are obtained for the selectivity became.

The activity of the catalyst therefore decreases within from about 1500 hours (of which about 300 hours reaction time) only slightly decreases. From this it can be concluded that the service life is much longer.

Of the main advantages of the method according to the invention given below.

a / It enables the production of Cyclohexanone from phenol under atmospheric pressure at 160 ° C., the yields are over 95%.

b / Compared to the most widespread processes today in this one process a distillation and the dehydrogenation step, what a results in significant toaster savings.

c / It enables the production of larger quantities of cyclohexanone from equal amounts of phenol.

d / The hydrogenation of the phenol only takes place with the uptake of 2 molecules Hydrogen; the reaction is therefore less exothermic than with conventional ones Procedures and so can be kept better under control.

e / In relation to the catalysts of the known process has the catalyst has greater selectivity and resilience.

f / It can be significantly compared to the known method with a lower hydrogen excess can be worked.

g / H2-N2 mixtures, e.g.

Ammonia synthesis gas can be used.

h / The catalyst used in the reaction is simple manufacturable.

i / The activated catalyst is not sensitive to air and can stored in the open air.

JP The catalyst has a long life, and after the When exhausted, its metal content can be recovered during regeneration.

k / The procedure can be carried out without substantial investment in the after the conventional, on two process steps based technology working establishment are introduced because most of the existing there Facilities is usable.

1 / Compared to the establishments that after the on two procedural steps based technology are much less investment funds for the construction of new plants with the same capacity is necessary.

The method according to the invention is illustrated by the examples below explained in more detail.

Example 1 In a reactor with an inner diameter of 22 mm are 20 ml of a 0.5 wt .-% Pd on Klinosorb 4 (grain diameter 1 to 1.4 mm) existing, activated supported catalyst introduced and per hour 0.113 moles of phenol and 0.68 moles (16.7 l) of hydrogen are fed in, giving an H2 / phenol ratio of 6: 1. The space velocity is 0.38 sec-1, the contact time 2.6 sec.

The gas chromatographic analysis of the conducted from the reactor into the condenser Reaction mixture gives 96.3 mole percent cyclohexanone and 3.7 mole percent cyclohexanol, i.e. the conversion is 100% Hydrogenation reactions are given in the table below. The examples show clearly that the process according to the invention also 100% conversion or over 98% selectivity made possible In Examples 2, 3 and 7 and also 8 to 10 were 20 ml of Klinosorb 4 containing 0.5% Pd was used as a catalyst. In the case of the examples 8 to 10, the catalyst was pretreated with acid before impregnation.

In Example 4, 20 ml of a 0.22 * Pd-containing catalyst applied.

In Examples 5 and 6 also contained in an amount of 20 ml of Klinosorb 4 used 1.0% Pd.

Table 1 No. of Temp. Mol-Rat. Phenol H2 dosage N room velocity Examples ° C H2: Phenol Einsp. Moles / hr 1 / hr 2 sec-1 moles / hr 2 169 6: 1 0.226 1.36 33.4 - 0.77 3 161 6: 1 0.113 0.68 16.7 - 0.38 4 155 6: 1 0.113 0.6a 16.7 - 0.37 5 151 6: 1 0.113 0.68 16.7 - 0.38 6 160 6: 1 0.226 1.36 33.4 - 0.77 7 151 6: 1 0.113 0.68 16.7 15 0.68 8 150 6: 1 0.113 0.68 16.7 - 0.38 9 16u 6: 1 0.226 1.36 33.4 - 0.76 10 170 6: 1 0.452 2.72 66.8 - 1.52 (Continuation of Table 1) No. of Contact Composition of the example time Rk.-Gamisches in mol% conversion Selektisec Cyclo-Cyclo-Phenol %% hexanone hexanone 2 1.3 94.6 2.4 3.0 97.0 97.6 3 2.6 96.3 3.7 - 100 96.3 4 2.7 93.2 6.2 0.6 99.4 93.8 5 2.6 93.5 4.5 - 100 95.5 6 1.3 92.3 1.7 6.0 96 98.2 7 1, 5 90.7 1.6 7.7 92.3 98.3 8 2.6 88.4 11.6 - 100 88.4 9 1.3 96.2 3.8 - 100 96.2 10 0.65 94.1 2.3 3.6 96.4 97.7

Claims (2)

PATENT CLAIMS 1. Process for the preparation of cyclohexanone from Phenol using Pd catalysts, at 120 to 180 ° C, thereby g e k e It should be noted that phenol vapors and containing hydrogen or hydrogen Gas mixtures through the bed of such a catalyst produced by applying 0.1 to 1.2 wt%, preferably 0.2 to 0.5 wt% Pd on an over stable alkaline Surface centers having a carrier was produced, being conducted, whereby the phenol metering rate based on 1 g of Pd 0.5 to 12 mol / hour, preferably 1.5 to 5.0 moles / hour. amounts to. 2. The method according to claim 1, characterized in that g e -k e n n z e i c h n e t that as a carrier with stable alkaline surface centers for cation exchange Capable aluminosilicates, preferably molecular sieves of the zeolite type are used will.