CS271737B1 - Method of cyclohexanol's catalytic dehydrogenation - Google Patents

Abstract

The purpose of the solution is the production of cyclohexanone with improved effectivity of the catalytic transformation of cyclohexanol to cyclohexanone. The above-mentioned purpose is achieved in the following way: the dehydrogenation is performed in two phases, in the first, isothermally and in the second adiabatically using copper and/or zinc on iron as the catalyser.

Description

The invention solves the epoeobic catalytic dehydrogenation of cyclohexenol to cyclohexanone.

The intermediate product of caprolactam production, cyclohexanone is produced in the saintly product by 74% by oxidation of cyclohexane by 25% by dehydrogenation of phenol, 2 cyclooxylamine and produced only in small capacity (Weieeermel K ,, Arpe HO .: Prommyel organic chemistry, SNTL Prague Hydrogens) cyclohexylidenimine and this is further hydrolyzed with water vapor to cyclohexanone;

Oxidation of cyclohexane aa is carried out by liquid phase air at a temperature of 398-438 K, a pressure of 0.8-1.5 MPa under the catalysis of acetates, naphthenates or flax salts of manganese or cobalt, as the primary product forms cyclohexyl hydroperoxide which Other cyclohexanone and other alcohols, adlpic acid, also glutaric and succinic, are predominantly present in the form of cyclohexyl ethers or other ethers. The conversion is therefore limited to a maximum of 10% in order to maintain the selectivity of 80 to 85%. The selectivity of the reaction can be increased by the oxidation procedure with the addition of boric acid. This leads to a reaction! of cyclohexyl hydroperoxide directly to the boronic acid ester of cyclohexenol, which is stable to oxidation. In this case, the selectivity of the reaction increases to 90% 1 in the conversion! to 12%, wherein the molar ratio of cyclohexenol to cyclohexanone is changed to 9 µl. Unreacted cyclohexane is separated from the products by distillation and recycled to the proceau. Cyclohexanone and cyclohexanol e are separated from the by-products by catalytic dehydrogenation. This reaction aa is carried out at an atomic pressure at 550 to 750 K using a catalyst most often based on zinc or medium. The degree of cyclohexenol conversion is approximately 90% selectivity to cyclohexanone is 95%.

He used only a two-step process to convert phenol to cyclohexanone and floods. The hydrogenation of the core to cyclohexanol is carried out on a nickel catalyst ea at 413 to 433 K and a pressure of 1.5 MPa, which is subsequently dehydrogenated under the conditions mentioned above. By introducing elective hydrogenation palladium catalysts ea, this two-step process has simplified the non-step process. When using palladium catalysts supported on alkaline earth metal oxides, e.g. Pd to CaO / AlgOg at a temperature of 413 to 443 K and a pressure of 0.1 to 0.2 MPa, the conversion is complete and the selectivity to cyclohexanone is greater than 95%.

Except when the palladium catalyst is used in the phenol stream in all processes, it is necessary to dehydrogenate cyclohexanol to cyclohexanone.

The cyclohexenol dehydrogenation process is simple, consisting of washing cyclohexanol, reaction and dispersing the reaction products. The cyclohexanol reacts at 430-460K. The vapors ea are superheated to 560-620K by the reaction slurry and passed into the reactor. The temperature dependence of the equilibrium constant of the reaction predetermines that reaction ea takes place at a temperature of 550 to 750 K. The use of a lower temperature is limited by the desired step of the cyclohexenol spring to cyclohexanone and the use of a higher temperature results in increased formation of subsequent products. pitch and / or carbon carry the catalyst. The reaction is sndothymic and requires the input of a considerable amount of energy to conduct the reaction as well as to maintain the reaction system at the desired temperature. In practice, ea supplies heat by circulating the heat carrier through the inter-tube preator. However, at low temperatures, the organic substance may be the organic substance, but at higher temperatures the inorganic salts and / or metals melted most frequently, and preferably the directly combustible gases from the combustion of the combusted medium as the heat supplier. The reaction eplodines ee are cooled indirectly by vapor-inlet cyclohexenol to 450-520 K. The resulting cyclohexanone, unreacted cyclohexanol and by-products, in particular cyclohexene and water, are separated from the hydrogen formed by cooling.

This mixture is separated by frequency de-distillation on multi-column columns, most often together with the cyclohexane oxidation product, which is essentially a mixture of cyclohexanone and cyclohexane and mixtures which have not separated in the treatment of the cyclohexane oxidation reaction mixture. Water and cyclohexane are separated from the more volatile components, then a mixture of so-called " Alcoholic portions are mainly hexanal, butanol, pentenol, cyclopentanol and cyclohexanone. The pure cyclohexanone, which is a comparative product and cyclohexanol, proceeds to the dehydrogenation process. The distillation residue is a mixture of organic compounds and a considerable amount of dicyclohexyl ether and cyclohexylcyclohoxanone.

The cyclohexanol-dehydrogenating dehydrogenation contains a significant amount of cyclohexanone, the presence of equilibrium retarding the rate of dehydrogenation, as well as significant amounts of pentylcyclohexane and butoxycyclohexane, which burden the dehydrogenation system as well as fractional distillation in particular energetically.

A catalyst used to effect the dehydrogenation of cyclohexanol is more widely used. Catalysts of zinc and copper are most commonly used. We know a zinc catalyst deposited on carbon (SU 249 354) or a supported catalyst deposited on ailica gel (SU 465 217), most preferably zinc and mine (US 2,552,300) catalysts prepared by various epoeobes (OE 1 954 476, SU 810 265), iron and zinc are added (PL 102 493), where the currency is deposited on the surface in an amount of from 1 to 500 ml / g per square meter of catalyst surface.

The addition of water (RO 79 492) to the incoming cyclohexanol positively affects the reaction efficiency as it retardes the cyclohexanol dehydroganate to cyclohaxene. However, a significant increase in cyclohexanol vapor with water up to 27% by volume (OE 2 347 097) presents considerable energy disadvantages. The addition of oxygen (PL 136 018) to the feed mixture allows the process to be carried out by adiabatic agents. However, there are higher safety requirements and less hydrogen is produced which can be used for hydro-aging purposes.

These drawbacks have eliminated the invention; which is based on the fact that the catalytic dehydrogenation of cyclohexanol ee takes place in two stages. In the first stage on the catalysts zinc on iron and / or me3 and zinc on iron at a temperature ranging from 673 K to 723 K and in the second stage on a catalyst me3 and / or mine and zinc on iron at a temperature of 473 K to 673 K. it consists in that the concentration of zinc on the iron support is at most 20% by weight, and the weight ratio of medium to zinc on iron is in the range from 0.01 to 100, while the iron support is at least 50% by weight. that the reaction in the second step e and adiabatics is carried out.

The advantage of this process is the increased conjugation of cyclohexanol to cyclohexanane as exemplified by the following examples.

Example 1

In one hour aa de-cycling feeds 7,521.3 kg of cyclohexanol and 3,418.8 kg of cyclohexanone in the oxidation product and 2,297.7 kg of cyclohexanol and 7,628.4 kg of cyclohexanone in the dehydrogenation product by Rectification distribution using energy in the form of water vapor e flows to a commercial product containing 10,291.9 kg of cyclohexanone and a distillate containing 9,805.5 kg of cyclohexanol and 616.2 kg of cyclohexanone · This distillate is next to the dehydrogenation stage · Evaporates ea directly with water vapor at 445 K, for · The reactor aa heats directly by burning natural gas to a temperature of 670 K. The reaction eplodines ea are cooled by direct-flowing vapors to a temperature of 670 K. a temperature of 500 K. By condensation of the liquefiable components e, the product from dehydrogenation contains 2,297.7 kg of cycles. lohexanol and 7,628.4 kg of cyclohexanone, which is recycled to the distillation plant.

Example 2

In one hour and a. To the de-distillation set, 7,521.3 kg of cyclohexanol and 3,319.2 kg of cyclohexanone in the oxidation product and 1,323.9 kg of cyclohexanol and 7,628.4 kg of cyclohaxaCS 271,737 B1 are fed into the dehydrogenation product by Rectification Division. the use of energy in the form of a water lip and a comparative product containing 10,300.4 kg of cyclohexanone and a distillate containing 8,832.6 kg of cyclohexanol and 801.2 kg of cyclohexanone. This distillate aa leads to a dehydrogenation step. It evaporates and indirectly by means of a water lip at 443 K preheated by reaction fumes to a temperature of 570 K and proceeds to the reaction system first into a tubular isothermal reactor filled with a zinc-on-iron catalyst and a 0/079 zinc to ferrous weight ratio catalyst and a media to zinc weight ratio of 0.028 and a media to zinc weight ratio of iron carrier of 0.078. The crust isothermal reactor ea is heated indirectly by the extraction of natural gas to a temperature of 670 K, the reaction eplodines leaving the adiabatic reactor are cooled down by indirectly vapor to 480 K, condensation of the liquid components yields a dehydrogenation product and a 1 323.9 kg * 4 kg of cyclohexanone, which is recycled to the daathilation set.

Example 3

In one hour and a daathilation file, 7,621.3 kg of cyclohexanol and 3,319.2 kg of cyclohexanone in the oxidation product and 1,101.7 kg of cyclohexanol and 7,628.4 kg of cyclohexanone in the dehydrogenation product are fed by rectification using energy in the form of water vapor is obtained from a comparative product containing 10,302.6 kg of cyclohexanone and the distillate containing 6,610.4 kg of cyclohexanol and 501.2 kg of cyclohexanone. This distillate ea led to the dehydrogenation stage. It evaporates indirectly with water vapor at 443 K with the reaction fumes to a temperature of 570 K, and the vapor enters the reaction system first into the tubular isothermal reactor, then into the adiabatic reactor. In both of the catalysts, the catalyst and the weight ratio of the medium to the zinc are 0.028 and the weight ratio. medium and zinc to iron carrier 0.078. The tubular isothermal reactor aa heats indirectly the appellation of natural gas to a temperature of 670 K. The reaction eplodines leaving the adiabatic reactor aa have been cooled by indirectly venting vapors to a temperature of 480 K. By condensation of the liquid components , 4 kg of cyclohexanone, which is recycled to the daathilation set.

The advantage of this process is the increased conversion of cyclohexanol to cyclohaxenone, resulting in at least lower costs and delaying unreacted cyclohexanol from cyclohexanone and recycling it to the dehydrogenation process. By improving the efficiency of the tracer system in the dehydrogenation set aa, the hourly steam consumption ^{in both} eamot and hydrogenation is reduced by 4/77 00, reducing the cyclohexanone atrata by converting it to the incoming benzene in production of 10.7 kg and the consumption of natural gas by »

12.8 m ³ .

Claims (3)

OBJECT OF THE INVENTION 1. A process for the catalytic dehydrogenation of cyclohexanol to cyclohaxanone, characterized in that it is carried out in two stages, in the first stage on a zinc-on-iron and / or honey-zinc-on-iron catalyst at a temperature of 573 K to 723 K; iron prl temperature 473 K to 673 K. 2. A process according to claim 1, wherein the zinc concentration on the iron support is at most 20% by weight, and the weight ratio of copper to zinc on iron is from 0.01 to 100, wherein the iron support is at least 50% by weight. 3. Catalytic dehydrogenation process according to claims 1 and 2, characterized in that the dahydroganation in the second step aa is carried out in the adiabatic catalyst layer.