CS257367B1 - A method of making a mixture comprising cyclohexanone and cyclohexanol - Google Patents

Abstract

The essence of the solution is a method of producing a mixture containing cyclohexanone and cyclohexanol by oxidizing cyclohexane in the presence of catalysts, preferably cobalt and/or chromium compounds in a single or multi-stage reaction system, which is characterized in that air or a gas containing oxygen is forced through the reaction mixture in an amount of 0.18 to 0.86 kmol of oxygen per hour per 1 m3 of the working volume of the reactor. Using the method, an increase in the selectivity of the oxidation of cyclohexane towards cyclohexanone and cyclohexanol by 4 to 6% is achieved.

Description

257367

The present invention provides a process for preparing a mixture comprising cyclohexanone and cyclohexanol by oxidizing cyclohexane in the liquid phase with oxygen or an oxygen-containing gas.

One of the processes in the production of cyclohexanone or cyclohexanol, which determines the consumption of raw materials and energy, is the oxidation of cyclohexane. By oxidation of cyclohexane in the liquid phase, a considerable amount of oxidation by-products is produced in addition to the desired products. Although a wide range of procedures for their economical use as secondary petrochemical raw materials are currently in progress, the economics of production in dependence on the amount of the emerging amount is significantly impaired. In the literature, some values of the reaction parameters and the construction of the reaction apparatus for the cyclohexane oxidation process increase the selectivity of the reaction towards cyclohexanone and cyclohexanol.

A process for the oxidation of cyclohexane in several or more reaction stages is known, with oxygen or an oxygen-containing gas being introduced into each stage in such a way that all oxygen is reacted or in excess corresponding to the concentration of the oxygen in the offgas of 1-2% by volume (BE pat .827 835). A multi-stage oxidation of cyclohexane is disclosed in which an increase in the amount of cyclohexane is achieved in each step, with cyclohexane and the oxygen-containing gas being supplied to each stage in a constant volume ratio. The respective amount of cyclohexane is fed to each stage and is proportional to the heat released and increases the efficiency of reducing the heat dissipated by the cyclohexane evaporation in each stage (US Pat. No. 503,846). A modification of this process is to obtain cyclohexanone and cyclohexanol, characterized in that the additional cyclohexane is dosed only in stages 2 and 3 in an amount of 5 to 20% of the amount of cyclohexane fed to the first stage, the temperature in each step is constant or decreasing from 1 to 5 ° C. Accordingly, the reduction of the formation of organic acids by 15% and by-products by 30% (U.S. Pat. No. 675,759) is achieved. An increase in the selectivity of the cyclohexane oxidation can also be achieved by a process in which the effective height of the liquid in the reactor is 1-2 m (Pol. Pat. No. 241914). In order to improve the cyclohexane oxidation process, several reaction devices have been proposed, which are characterized mainly by the air distribution design (GDR Pat. No. 223,644, U.S. Pat. No. 4,211,111, U.S. Pat.

Although in the above-mentioned procedures the increase in the selectivity of oxidation of cyclohexane, published and also in the production of cyclohexanone in CSSR, is achieved, the specific consumption of raw materials in this area point to considerable reserves in this area.

It has been found experimentally that by appropriate choice of reaction parameters it is possible to further increase the selectivity of cyclohexane oxidation towards cyclohexanone and cyclohexanol.

SUMMARY OF THE INVENTION The present invention provides a process for producing a mixture comprising cyclohexanone acyclohexanol in a liquid phase with oxygen or oxygen-containing gas at one or more reaction stages at temperatures of 130 to 220 ° C and a pressure of 0.5 to 1.5 MPa in the presence of a catalyst, most commonly salt. cobalt and / or chromium. It is characterized by the fact that air or oxygen-containing gas is forced through the reaction mixture formed by cyclohexane and its oxidation products in an amount of 0.18 to 0.86 mmol of oxygen per hour per m 3 of the reactor working volume. Indeed, the reaction para-meters are maintained at such levels as to achieve efficient utilization and oxygen demand of the products. The best results from the selectivity and reactor costs are achieved when oxygen or oxygen-containing gas is forced through an effective reaction volume of 0.7 kilograms of oxygen per m 3 of reactor working volume. The resulting reaction mixture is further processed by a known method after separation of unreacted cyclohexane which is recycled to the oxidation process.

By utilizing the process of the present invention, a significant increase in the cyclo-manoxide process of the oxidation process to cyclohexanone and cyclohexanol is achieved, reducing the formation of by-products. With greater efficiency, it is possible to carry out the further separation of cyclohexanone and cyclohexanol from the reaction mixture, and in addition to a significant reduction in the specific consumption of the raw material, a reduction in specific energy consumption is also achieved. A further advantage of this invention is the ease of implementation, the process of oxidation process and the possibility of application in various types of oxidation reactors. The advantages of the present invention are illustrated by the following examples: Example 1 (comparative) In an oxidation reactor through which cyclohexane with a catalyst of 2.5 ppm cobalt, at a temperature of 159 to 165 degrees Celsius and a pressure of 0.9 MPa, air is forced through the re-action volume. an amount of 0.88 oxygen per hour in the form of an air per m 3 of the reactor working volume. The selectivity of cyclohexane oxidation of cyclohexanone and cyclohexanol is beyond 82.5 to 83.5%. Example 2 In an oxidation reactor, under the conditions of Example 1, 0.6 g of oxygen are passed through the reaction mixture per hour in air at 1 m < 3 > obje-

Claims (1)

Process for preparing a mixture containing cyclohexanone and cyclohexanol by oxidizing cyclohexane in liquid phase with oxygen or oxygen-containing gas in one or more stages at temperatures of 130 to 220 ° C, pressure of 0.5 to 1.5 MPa in the presence of a catalyst, preferably cobalt salts and / or Chromium, characterized in that air and / or an oxygen-containing gas in an amount of 0.18 to 0.86 kmol, preferably 0.70 kmol of oxygen per hour per hour, is passed through the reaction mixture in the reactor consisting of cyclohexane-Alesin and its reaction products. m ^{3 of the} working volume of the reactor, the air and / or gas leaving the reaction system containing 0 to 5 volume percent oxygen.