DE2014567A1 - Epsilon - caprolactam prodn using aluminiumo - Google Patents

Abstract

In catalytic rearrangement of cyclohexanoxime to form epsilon-caprolactam in gaseous phase at 250 to 400 degrees C, using an Al-oxide catalyst contng. 10-50 wt. % boric acid or boron oxide, the catalyst also contains 0.1-10 wt. % (w.r.t. total catalyst) of Cr, Rh, Ir, Pd, Pt, Zn, Cd, Cu, Ag an d/or Au. Wt. ratio of cyclohexanoxime catalyst is 1:1 to 4:1. The catalyst ensures high yield of epsilon -caprolactam.

Description

Process for the production of 6-caprolactam Addition to patent. ... ... (Patent application P 19 02 458.9 -O.Z. 25 977) It is z. B. from the made known Documents of the Dutch patent application 67.16887 known that one lactams by catalytic rearrangement of cycloalkanone oximes in the gas phase to boric acid The catalysts contained in the product are obtained in high yields if a sulfate is used, eih Sulphite or a phosphate of an element of the 2nd main group of the periodic table clogs. The high yields given in these documents are only relatively small loads on the catalyst, d. H. with small space-time yields achieved.

The main application P 19 02 458.9 is a method for Production of t-caprolactam by catalytic rearrangement of cyclohexanone oxime in the gas phase at 250 to 400 ° C. on a 10 to 50% by weight boric acid or boron oxide containing alumina catalyst using a catalyst the additional 0.1 to 10 wt .-, based on the total catalyst manganese, nickel and / or cobalt.

It has now been found that the process of parent application P 19 02 458.9 can be trained if you use catalysts that instead the additions of manganese, nickel and / or cobalt those of chromium, rhodium, iridium, Contains palladium, platinum, zinc, cadmium, copper, silver and / or gold.

When using the catalysts modified according to the invention is obtained in the same way as with the catalysts the main login high Yields of caprolactam, even if the catalyst is heavily loaded; with others In other words, a substantial improvement in the space-time yield is achieved.

The rearrangement conditions are known per se. The cyclohexanone oxime becomes either vapor or liquid or in solid form over or on the at Reaction temperature located catalyst passed. The rearrangement is between 250 and 400 00, preferably between 270 and 370 OC. You can do it Carry out the process at normal pressure, under reduced or slightly overpressure. If the process is carried out under reduced pressure, the pressure range becomes from 20 to 200 torr is preferred. If the procedure is carried out under overpressure, In general, pressures above 2 atm are not used.

The process can be carried out in the presence of inert gases, e.g. B. carbon dioxide, Carry out argon, nitrogen or water vapor.

This embodiment is particularly important when performing in the Fluidized bed plays a role, since the catalyst is then preheated appropriately Inert gas set in whirling motion. It is beneficial to be from one Cyclohexanone oxime goes out, which from its production still has a certain water content has, e.g. B. about 1 to 10 wt. In general, about 5 to 70 vol. Inert gas added (based on the total mixture) depending on whether the process is or overpressure or under reduced pressure, with higher pressure also uses more inert gas.

The catalysts used for the process are produced in a manner known per se. Aluminum oxide, which in its various modifications, such as alumina, bayerite or corundum, can be used with boric oxide or boric acid soaked, the ratio between boron oxide and aluminum oxide between 1 : 9 and 1: 1, calculated as a weight ratio. With the preferred used Catalysts the proportion of boron oxide is 25 to 50% by weight.

These catalysts are either used from the outset when they are applied boric acid or boron oxide or preferably subsequently instead of the one in the main patent mentioned aqueous solutions of manganese, cobalt or nickel salts aqueous solutions of salts of chromium e.g. B. chromic anhydride, rhodium, e.g. B. rhodium chloride, iridium, z. B. iridium chloride, palladium, e.g. B. palladium nitrate, platinum, e.g. B. platinum chloride or platinum nitrate, zinc, e.g. B. zinc nitrate, cadmium, e.g. B. Oadmium Nitrate, Copper, z. E. copper nitrate, silver, e.g. B. silver nitrate, and / or gold, e.g. B. gold chloride, and in this way brings the metals in an amount of 0.1 to 10 wt. Solutions of the nitrates are preferably used, but other soluble ones can also be used Salts, e.g. B.

Use acetates, sulfates or formates. The catalysts will at about. 50 'to 200 ° C and then dried to convert the applied Salts annealed into the Al205 / B203 metal oxide mixed phases at 600 to 850 00. The shaping the catalysts are carried out in a manner known per se, for. B. Pasting of catalyst and carrier with a little water, mixing in a kneader, pressing the mass into strands or pills, drying and glowing at the specified temperature.

Depending on the type of catalyst arrangement, catalysts are in pill, Cylindrical or strand shape or used with other geometric shapes. With permanent Catalysts are either particles with diameters of 1 to 5 mm or with Catalyst 'coated tubes or reticulated supports are used. However, it is preferred to use the catalyst in split form as a fluidized catalyst. In this case is it expedient; Catalyst particles with diameters from 0.005 to 1.5 mm, in particular from 0.2 to 1.9 mm. %. o «.> The layer height of the The catalyst bed is expediently chosen so that there are residence times of the oxime on the catalyst layer between 0.01 and 20 seconds, preferably between 0.1 and 3 seconds.

It is an advantage of the process that the catalyst is heavily loaded can e.g. B. with 1 part by weight of cyclohexanone oxime per part by weight per catalyst and Hour. But there are also higher loads, e.g. B. up to 4 parts of cyclohexanone oxime Possible per part of catalyst and hour. After a while, the catalytic converters tire and then have to be regenerated, e.g. B. by heating in air flow to 600 to 800 cc.

When using fixed bed catalysts or catalysts in In the fluidized bed you have to switch on an energy generation period from time to time. It can therefore be advantageous to work in the vortex flow process, whereby one is constantly feeds fresh or regenerated catalyst and so much catalyst through the vapors Can be discharged from the reaction space as one can lead to the separate regeneration want.

The lactam produced by the process of the invention has a very high purity.

The parts given in the following examples are parts by weight.

Example 1 In a vertical, electrically heated, and with a glass frit tube of 200 cm length and 100 mm diameter Bred 1500 g of catalyst to a reaction temperature of 350 ° C to 360 ° C. then 3.48 kg of cyclohexanone oxime with a water content of 5% 0 are passed through a nozzle passed the catalyst. The fluidized bed is created by supplying 3500 standard l / h of nitrogen maintain.

The catalyst used consists of 51 wt .- / a aluminum oxide, 48 % By weight boron oxide and 1% by weight palladium. It has a grain size of 0.5 to 1 mm and an inner surface of <50 m2 / g. In the catalyst room maintain a pressure of 800 torr.

The vapor mixture escaping from the reactor is poured into a bubble-cap tray column passed, in which the lower-boiling components and the water are removed overhead while the raw lactam is being condensed.

Obtained after distillation of the crude lactam under reduced pressure 3.14 kg of 8-caiprolactam d. see 94.9 ß of theory based on the anhydrous used Cyclohexanone oxime.

Example 2 In an apparatus which is constructed analogously to that in Example 1 described but with a device for continuous feeding and removing catalyst is provided at a temperature of 350 0 and a pressure of 850 Torr per hour 7.5 kg of cyclohexanone oxime with a water content of 4.9% by weight to 3.5 kg of catalyst, which passed through the reactor during this time be relocated.

The fluidized bed is maintained by supplying 3500 standard l / h of nitrogen.

The catalyst consists of 53% by weight of aluminum oxide with 45% by weight Boron oxide and 2% by weight zinc and has a grain size of 0.5 to 1 mm.

The vapor mixture escaping from the reactor is as in example 1 described passed into a bubble tray column in which the crude lactam condenses. ~ After the crude lactam has been distilled under reduced pressure, 6.78 kg of caprolactam are obtained d. p. 95 ', 1 of the theory, based on the anhydrous cyclohexanone oxime used obtain.

Example 3 As described in Example 1, 6.2 kg of cyclohexanone oxime are used with a water content of 3 wt .-% at a temperature of 360 ° C and a pressure from 800 to 850 Torr on 3.0 kg of a catalyst consisting of 50.3% by weight of aluminum oxide, 48.2% by weight boron oxide and 1.5% by weight chromium rearranged to caprolactam. The dwell time in the catalyst layer is approx. 2 sec.

After distillation of the crude lactam obtained at about 2 torr one 5.64 kg of 6-caprolactam, that is 93.9% of theory, based on the amount used anhydrous cyclohexanone oxime.

Example 4 As described in Example 1, 7.0 kg of cyclohexanone oxime are used with a water content of 5% by weight on 3.0 kg of catalyst of composition 54 Weight aluminum oxide, 45 weight percent boron oxide and 1 weight percent silver at one temperature rearranged from rv 350 0 and a pressure of 850 torr to caprolactam.

Obtained after distillation of the lactam under reduced pressure 6.32 kg of lactam, that is 94.9% of theory, based on the anhydrous used Cyclohexanone oxime.

Claims (3)

Claims 1. Further training of the process for the production of k caprolactam, by catalytic rearrangement of cyclohexanone oxime in the gas phase at 250 to 400 0 an alumina catalyst containing 10 to 50 wt .; boric acid or boron oxide, in which a catalyst is used which additionally contains 0.1 to 10% by weight on the total catalyst, containing manganese, nickel and / or cobalt, according to patent. ... ... (patent application 'J19 02 458.9 -O.Z. 25 977) characterized in that one uses catalysts that instead of the additives of manganese, nickel and / or Cobalt those of chromium, rhodium, iridium, palladium, platinum, zinc, cadmium, copper, Contains silver and / or gold. 2. The method according to claim 1, characterized in that the Performs rearrangement in the presence of steam or another inert gas. 3. The method according to any one of claims 1 or 2, characterized in that that the weight ratio of cyclohexanone oxime to the catalyst is 1: 1 to 4 : 1 holds.