SU586838A3 - Method of preparing cyclohexanone oxime - Google Patents

Description

(54) METHOD OF OBTAINING OXIM CYKLSHEXANON

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The invention relates to an improved process for the preparation of cyclohexane oxime.

A method of producing cyclohexanone oxime by reacting cyclohexane and a hydroxylammonium salt, in which an aqueous reaction mass containing a buffer, having an acidic reaction and containing ammonium salt as a buffer salt, is circulated between the hydroxylammonium salt, where the nitrate ions are catalytically recovered, and the sample is in a step of a factor of a factor or a member of a component or a member of a vessel or a sample or a vapor band, is in a position of a non-volatile zone; hydrogen, and a step for the production of cyclohexanone oxime, where the hydroxylammonium ions interact. with cyclohexanone. Prior to applying for the synthesis of hydroxylammonium SALT, the circulating aqueous reaction mass is enriched. necessary nitrate ions or the addition of nitric acid, or, mainly, the adsorption of nitrous gases.

As a catalyst for the reduction of nitrate ions, for example, palladium or an alloy based on palladium and platinum on a carrier, for example, coal, is used.

OR alumina, while the carrier contains 5-2% by weight of catalyst. Since the activity of such a catalyst decreases upon contact with organic compounds, such as convertible cyclohexanone or formed cyclohexanone oxime, therefore, the total content of dissolved ketone and oxime in the circulating fluid is reduced to O, O2 wt.% By heating the circulated fluid at 5 ° C in the presence of nitrous gases before the liquid is supplied to the stage of the emission of the hydroxylammonium salt 1).

However, with this method, it is necessary to subject said heat treatment to a large amount of recycled liquid per ton of the desired product. In addition, it is not possible to apply an excess of hydroxylammonium salt, which may decompose during heat treatment; at this temperature, the content of ammonium ion in the circulating liquid becomes low, which leads to more rapid poisoning of the catalyst.

In order to intensify the process, a method is proposed in which the recycled waste heat is partially or fully heated at 12 ° C-175 ° C and at an absolute pressure of more than 1 atm. G1 {) The proposed method for the preparation of cyclohexanone oxime consists in reacting cyclohexanone with a hydroxylammonium salt with recycling an aqueous reaction mass having an acid reaction and containing ammonium salt as a buffer salt, by heating the recycled liquid at 120-175 ° C and Ac pressure 1.1 atm, and as the temperature rises, the pressure should also be increased to maintain the treated repirculating fluid in the liquid state. With this temperature and pressure regime, it is possible to almost completely eliminate cyclohydroxylamine and the catalytic dyes formed from it. Periodic treatment has the disadvantage that the required composition of the entire recirculated liquid changes periodically, which complicates the continuous process. Therefore, it is preferable to heat part of the recirculated liquid, for example, 4-2O% of the total recycled liquid, preferably 512% of the total recycled liquid. In this heat treatment, the recycled liquid is brought into contact with nitrous gases, which is a gas that contains nitrogen dioxide, optionally mixed with nitrogen monoxide, and in which nitrogen dioxide can also be formed in place, for example, from monoxide, and oxygen; The gas may contain inert gas, for example nitrogen. Preferably, nitrous gases are used which contain 0.4-2.5 mol of mono-nitrogen oxide per 1 mole of nitrogen dioxide. The amount of nitrous gases with which the treated greed is brought into contact must be greater than the amount consumed in the decomposition of ammonium ions. Good results are obtained when applying partial nitrous pressure (sum of partial pressures of nitrogen dioxide and: nitrogen monoxide), which is greater than the pressure of nitrous gas of nitric acid at the temperature at which the heat treatment is carried out. This pressure of nitrous gas exceeds 0.15 at @ 120-175 ° C. The drawing schematically shows a variant of the proposed method. Pipeline 1 supplies hydrogen to stage A of the preparation of the hydroxylammonium salt, where the palladium-containing catalyst is suspended in the reaction medium. Unreacted hydrogen, if necessary, other exhaust gases, is removed via conduit 2. At stage A, conduit 3 is supplied with a reiriruntuable reaction medium, which, after being enriched with hydroxylammonium salt, is fed via conduit 4-to step B to produce cyclohexanone oxime. Cyclohexanone, if necessary together with an organic solvent for cyclohexanone and cyclohexanone oxime, is fed through line 5 to step B, and the oKCHjvf of cyclohexanone formed, if necessary, in solution in an organic solvent, is withdrawn through line 6. By lines 7, 8, 3 liquid recycle. are cast into step A of the preparation of the hydroxylammonium salt. A partial stream of recirculated liquid is fed to column B through a regulating valve 9 and pipeline 10 and then through line 11 through reaction vessel D and condenser 17 and through line 3 is recycled to stage A. Nitrous gases are fed into the process via line 12. Most of the supplied nitrous gases through the valve 13 and the pipeline 14 is fed into the column. B where they are absorbed at a relatively low temperature, e.g. O-6 ° C, with simultaneous formation of nitric acid. The remaining part of the nitrous gases supplied through the pipeline 12 through the valve 15 is fed into the vessel G, which is maintained at an absolute pressure of at least 1 atm at a temperature above 120 ° C, for example at 120-175 ° C, and in which it is catalyzed. The compounds are decomposed in the presence of nitrous gases. The quantities of the reaction vessel D of nitrous gases supplied to the Biv column can be easily controlled using valves 13 and 15. The nitrous gases supplied to the reaction vessel can also be absorbed in the liquid flowing out of the absorption column B at a temperature below 60 ° C and the resulting In this way, the liquid enriched in nitrous gases can be fed into the reaction vessel G. It is also possible to supply the entire amount of nitrous gases to the reaction vessel G. In such a case, the nitrous gases are supplied in such an amount that a sufficiently large amount from the reaction vessel D to the absorption column C can be supplied via line 14 to form the required amount of nitric acid. Unabsorbed gases are removed through a reducing valve 16. The products formed in the reaction vessel D are mainly monocarboxylic and dicarboxylic acids, which do not poison the catalyst. These compounds remain in a small amount in the recirculated liquid, since they are mainly discharged together with the cyclohexanone oxime formed through line 6. Example. In the continuous production of cyclohexanone oxime, in which palladium-on-carbon catalyst (weight,% palladium) is used in step A, is recycled; ma (16.7 kg / h) through the pipeline 7, the liquid has the following composition, mol / kg: Nz PO 1.13; NH4HjPb4 l, 01; NH4KOil.39 (MHjOH) PO 0.02; HgO 36.55. Organic compounds are contained. liquids as an impurity in the amount of 4OO chumn, calculated as carbon. Meanwhile, the cyclohexanone oxime is contained in the amount of cyclohexylamine 17, carboxylic acids 80 and unknown amino compounds 302 ppm. Approximately 6% of the liquid recycled through the pipeline 7 is fed into the absorption column B through the control valve 9 and the pipeline 10 and then through the pipeline 11 B to the reaction vessel G. Through the pipe 12 and the open valve 15 in the reaction vessel D serves 74O l / h nitrous gases and then through the pipeline 14 they are served in the absorption column. G,. The gas supplied through the pipeline 12 has an absolute pressure of 6-7 atm and the following composition, vol.%: KO .5,2; liOg 5.1; N2 79.9. The temperature in the reaction vessel D is maintained at 125 ° C by heating with steam. The temperature in the absorption column B is maintained at 40 ° C using a coolant not shown in the drawing. The absolute pressure in the G and C columns is 6-7 atm. The waste gas discharged through the reduction fotopan 16 has the following composition, vol.%: CO O, 1; KjO 0, OO5; O 6.1; 6.2; Ng 87.6. Discharged from the reaction vessel G through line 3, the liquid has the following composition, mol / kg: 23, HHOj 6.15; HjPO 1.01. In addition, the liquid contains 26O chumpn. organic compounds (calculated as carbon), and 258 h / ml. total content are non-harmful carboxylic acids. There is no cyclohexanone oxime and cyclohexylamine in the liquid. 1. Method of obtaining cyclohexanone oxime by reacting cyclohexanone and hydroxylammonium salt with recycling an aqueous reaction mass, having an acid reaction and containing ammonium salt as a buffer salt, when heated in the presence of nitrous gases, characterized in that, in order to intensify the process, it is recycled the liquid is partially or fully heated at 120175 ° C and at an absolute pressure of more than 2. The method according to claim 1, characterized in that 5-12% of the recirculated liquid is heated. Sources of information taken into account in the examination: 1. Patent of England No. 1283894, cl. C 2 C, O2.O8.72.

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