CS271736B1 - Method of cyclohexanone production by means 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 vapours containing cyclohexanol are left to treat the catalyser with a weight ratio of copper to zinc ranging from 0.01 to 100:1 at the weight ratio of these metals to the carrier, which is metallic iron, in range of 0.01 to 1:1.

Description

(57) The aim of the solution is to produce cyclohexanone with improved efficiency of the catalytic conversion of cyclohexanol to cyclohexanone. This is achieved by the addition of cyclohexanol-containing vapors to a catalyst with a cyclohexanol. a weight ratio of medium to zinc in the range of from 0.01 to 100: 1 at a weight ratio of these metals to carriers that are metallic iron in the range of 0.01 to 1: 1.

271 736 (11) (13) bl (51) Int. Cl. ⁵ C 07 0 49/403

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The present invention provides a process for the production of cyclohexanone by catalytic dehydrogenation of cyclohexanol.

Cyclohexanone as an intermediate of caprolactam production is produced on an industrial scale from phenol or cyclohexane. The phenol is most often produced by hydrogenation to cyclohexanole, which is dehydrogenated to the final product. It is produced from the cyclohexane, most often prepared by the hydrogenation of benzene, by oxidation to form a mixture of cyclohexanol and cyclohexanone, from which, after separation, the cyclohexanol is dehydrogenated to cyclohexanone.

Cyclohexanone dehydrogenation reaction

-C H _{i, l} sep> 0 -C ₁₀ H + H ₂ and ^{H 6} = 5 kJ / mol is endothermic and requires the supply of substantial amounts of energy required to complete the process and maintain the desired temperature. The temperature dependence of the reaction equilibrium constant determines that the process is carried out in the vapor phase at 550-750 K. The use of a lower temperature is limited by the desired degree of conversion of cyclohexanol to cyclohexanone and the use of a higher temperature results in increased formation of subsequent products .

The process is carried out, for example, in several technological stages. Liquid cyclohexanol, on an industrial scale, most often containing an additive from its production process, is vaporized indirectly with water vapor at a temperature of 430 to 460 K. The vapors are then indirectly superheated with a reaction vessel to a temperature of 560 to 620 K and advance to the reactor. They pass through a catalyst embedded in tubes of a tubular reactor operating isothermally at a temperature of 640 to 700 K. With respect to the desired temperature, in practice, heat is supplied by circulating the heat carrier through the inter-tube space. The carrier of heat at lower temperatures may be an organic substance, but at higher temperatures molten inorganic salts or metals are most often gases, preferably combustion gases. The reaction products leaving the reactor are cooled to a temperature of 480-520 K indirectly by the vapors of cyclohexanol entering the reactor. From the cooled reaction gases, cyclohexanone, unreacted cyclohexanol, cyclohexane, water and other by-products are separated indirectly from water by condensation with water followed by cooled glycol. Said mixture is distilled by distillation to separate the product.

The hydrogenation process can be modified by the addition of oxygen (PL 136 018), water (RO 79 492, DE 2 347 097) or other substances in the reaction. The addition of oxygen, optionally oxygen and hydrogen, to the reaction mixture allows the process to be carried out adiabatically.

The economics of the process of dehydrogenating cyclohexanol to cyclohexanone is largely determined by the catalyst used. In terms of composition, a variety of catalysts, as well as industrially utilized catalysts, are known.

On the basis of phosphides, the known nickel catalyst is most often promoted by sodium (SU 716 583) in the form of hydroxide- and cobalt catalyst (SU 632 387). The cobalt catalyst is most often used in the form of a so-called catalyst carrier. felt turf (SU 697 177, SU 856 939). Also known are magnesium catalysts (Emeljanov NP: DAN BSSR 12 1968, 10, 914-7) and palladium-ruthenium membrane catalysts (Basov NL ...: Sov.-fr. seminar after catalysis, Sb. Doc. Moscow 1983, 34 -7).

The zinc catalyst can be deposited on carbon (SU 249 354), in the form of zinc oxide (RO 66 847), in a chromium alloy (Gluzman SS ...: Tr. Vses. Nu. Issled. Proc., Inst. Monomers 1 1968 , 1, 82-9, Zakrevskij VK ...: Moscow 1980. 9,

527-8) or in the form of zinc chromate (SU 348 540, RO 79 942).

Classically mentioned copper catalyst for the title process requires low temperatures and a small load is required for the conversion required (Orizarsky I .: Geterogenyje Catalysts Trudy Meždu narodnogo Simpózia 3 rd. 1975, publ. 1978 Izd. BAN Sofia, Vladea R. ...: Rev. Chim. (1980, 8, 759-62), a significant regulation of cyclohexanol vapors with water up to 27% by volume. (DE 2 347 097), which has considerable mechanical and technological disadvantages.

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For this reason, it has to be used as a catalyst in the form of alloys or supported on a support. Sword catalysts are known. in combination with manganese (SU 697 179, SU 979 423), with magnesium (SU 411 888, Zrblova I.P. ...: Chim. prom-st, Moscow 1979. 12,

713-14) with a calcium (Kozlov N.S. ...: Vesci AN BSSR, Ser. Chim. Navuk 1978, 5, 84-6).

The copper catalyst in combination with aluminum is either. in the form of an alloy (Petrova V, ...:

Chim. Ind., Sofia 1983, 9, 401-3) or in the form deposited on alumina (SU 522 853). In combination with silicon it is promoted by potassium oxide (Belskaja R.I. ...: Vesci AN BSSR, Ser. Chim. Navuk 1975, 2, 97-102) or in the form coated on silica gel (Kocurkova L. ...:

Chem. direct, 30 1980, 2, 71-4). It is deposited on the carbon with palladium (Red L.: Chem.

Avg. 29 1979, 3, 127-8) or is applied to the so-called. jungite, which is a mixture of oxides (SU 910 178).

Catalyst oxide as a catalyst is most often used in combination with chromium trioxide (JP 83 157 741) promoted by barium oxide (PR. 1 513 220) or barium oxide and graphite (SU 574 433). A good catalyst also appears to be in combination with chromium and magnesium (Belskaya RI ...: Vesci AN BSSR, Ser. Chim. Navuk 1977, 4, 41-5), possibly with cobalt (JU 80 136 241), with cobalt on phosphide base (SU 891 145) or with cobalt on a carrier. turf felt (SU 936 989).

Most commonly published and probably also used are zinc oxide copper catalysts (CS 151 166, Emeljanov NP: DAN BSSR 11 1967, 3, 233-6) and can be deposited in the form of oxalate (PR 2 030 602, US 3 652 460) followed by oxidation and hydrogenation of the catalyst in three cycles. The modified can be 2: 1 with barium oxide and ruthenium dioxide (SU 978 909) with sodium carbonate (GB 1 060 484). The catalyst of the medium and zinc may be modified with chromium (Medvedeva O.N. ...: Pr-organ, products, Moscow 1982, 15-22) or with calcium, barium and strontium (Belskaya R.I.

...: Vesci AN BSSR, Ser. chim. (1981, 6, 112-6).

It is known to produce cyclohexanone by catalytic dehydrogenation of cyclohexanol using a zinc catalyst on iron. The catalyst is prepared from galvanized low-carbon iron sheet by cutting and molding into tubes of the desired size. The zinc content of the catalyst is approximately 7% by weight. The above-prepared catalyst at the shear point of the sheet has an exposed iron support. The average conversion of cyclohexanol at about 673 K is about 75%. Increasing the temperature in the reaction makes it possible to increase the conversion, but the selectivity of the reaction decreases proportionally and, as a result, the raw material costs increase and the purification process of cyclohexanone is complicated. It is also desirable to regenerate the catalyst for a longer time by burning the so-called " Polymer to compacted pitch using air.

Known is a process for the production of cyclohexanone by catalytic dehydrogenation of cyclohexanol, characterized in that a vapor containing cyclohexanol by treatment of the catalyst MEA zinc on an iron carrier (PL 102,493) · MEA is applied to the surface in an amount of 1.10 "· ^ to 500.10 ^- ^ kg per square meter of catalyst surface. The average conversion of cyclohexanol, as well as the selectivity of its conversion to cyclohexanone, is somewhat higher than with the use of a zinc catalyst on iron, but nevertheless the economics of the process are marked by the aforementioned drawbacks.

These drawbacks of the process for the production of cyclohexanone by catalytic dehydrogenation of cyclohexanol at 550 to 750 K on a zinc catalyst on a ferrous support are overcome by the invention, which is based on the addition of cyclohexanol vapor to a catalyst containing copper and zinc by weight. 01 to 100: 1, wherein the weight ratio of these metals to the metal iron support is in the range of 0.01 to 1: 1.

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Example 1

Per hour, 7,302.2 kg of cyclohexanol and 3,319.2 kg of cyclohexanone in the oxidation product and 2,230.8 kg of cyclohexanol and 7,406.2 kg of cyclohexanone in the dehydrogenation product are fed to the distillation set. A rectification separation using water vapor energy yielded a commercial product containing 9,992.1 kg of cyclohexanone and a distillate containing 9520 kg of cyclohexanol and 501.2 kg of cyclohexanone. This distillate is passed to the dehydrogenation step. Evaporate indirectly with water vapor at 445 K, preheat reaction fumes to 590 K, and vapors pass to a reaction system containing a zinc-on-iron catalyst with a weight ratio of zinc to iron carriers of 0.079 · The reaction system is indirectly heated by burning natural gas to 670 K The reaction fumes are cooled by indirectly entering vapors to a temperature of 500 K. Condensation of the liquid components yields a dehydrogenation product containing 2,230.8 kg of cyclohexanol and *

406.2 kg of cyclohexanone, which is recycled to the distillation set.

Example 2

Per hour, 7,302.2 kg of cyclohexanol and 3,319.2 kg of cyclohexanone in the oxidation product and 1,285.3 kg of cyclohexanol and 7,406.2 kg of cyclohexanone in the dehydrogenation product are fed to the distillation set. Rectification using water vapor energy yielded a commercial product containing 10,000.4 kg of cyclohexanone and a distillate containing 8575.3 kg of cyclohexanol and 501.2 cyclohexanone. This distillate is passed to the dehydrogenation step. It is evaporated indirectly with water vapor at 443 K, preheated by reaction fumes to 580 K, and the vapors pass to a reaction system containing a catalyst with a media to zinc weight ratio of 0.028 and a media to zinc weight ratio of iron carriers of 0.078. The reaction system is heated indirectly by burning natural gas to a temperature of 670 K. The reaction products are cooled by indirectly entering vapors to 490 K. into the distillation file. .

The advantage of this process is the high conversion of cyclohexanol to cyclohexanone, resulting in a lower cost of separating unreacted cyclohexanol from cyclohexanone and recycling it to the dehydrogenation process.

By improving the efficiency of the reaction system in the dehydrogenation set, the hourly steam consumption of both the dehydrogenation itself and the distillation is reduced by 4.63 GJ, the loss of cyclohexanone in terms of the incoming benzene to 8.3 kg production and natural gas consumption is reduced by 12, 4 iA *

Claims (2)

OBJECT OF THE INVENTION A process for the production of cyclohexanone by catalytic dehydrogenation of cyclohexanol on an iron-on-zinc catalyst at a temperature of 550 to 750. The process is characterized in that the vapors containing cyclohexanol are coupled to a catalyst with a cyclohexanol content. a weight ratio of medium to zinc in the range of from 0.01 to 100: 1, wherein the weight ratio of these metals to the metallic iron supports is in the range of 0.01 to 1: 1.