RU2422434C1 - Method of producing esters from caprolactam production wastes - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to synthesis of esters from the alcohol fraction of caprolactam. The method of producing esters from caprolactam production wastes is realised via esterification of organic acid and alcohol in autocatalytic heat release conditions which support the esterification reaction at temperature 40-130C using a catalyst in form of cation-exchange resin which is pre-treated with sulphuric acid in amount of 0.4-2 wt % of the weight of the loaded material with cooling down of the reaction mixture before separating the two phases. ^ EFFECT: high efficiency of the method. ^ 2 cl, 2 tbl, 2 ex

Description

The invention relates to the field of synthesis of esters from the alcohol fraction of caprolactam, which are used as solvents of many organic compounds, especially valuable as solvents of nitrocellulose. They are used in the manufacture of varnishes, paints, artificial silk, the petrochemical industry, and are most in demand in the food industry and perfumery (as a perfume).

The essence of the invention lies in the implementation of the process of synthesis of esters using a catalyst - a cation exchange resin, so that the esterification reaction is carried out under conditions of autocatalytic heat generation that supports the reaction. The cation exchange resin is pretreated with sulfuric acid. Caprolactam production waste - the alcohol fraction of caprolactam - is used as feedstock.

A known method of producing esters of dicarboxylic acids With ₂ -C ₆ and alcohols (Patent No. 2373188, publ. 20.11.2009, C07C 69/02, C07C 67/03). The present invention provides a method for producing esters by esterification of a mixture of mono- and dicarboxylic acids C ₂ -C ₆ obtained by evaporation of aqueous-acidic effluents from caprolactam production on acid catalysts in the presence of a third component (benzene) at a temperature of 80-90 ° C until complete stopping the release of water. The disadvantage of this method is the need to introduce a third component (benzene), which also complicates the further distillation distillation.

A known method of producing esters of carboxylic acids (RF Patent No. 2283299, publ. 2003.06.27, C07C 87/08, C07C 69/80). The present invention relates to an improved method for producing esters of carboxylic acids, which find their application in varnish resins, as constituent paints and varnishes, as plasticizers for plastics. The proposed method consists in the interaction of di- or polycarboxylic acids or their anhydrides with alcohols, the reaction water being removed by azeotropic distillation, the liquid removed from the reaction by azeotropic distillation is completely replaced with alcohol again. This method shows good yield results (phthalic anhydride), as well as a decrease in the time of esterification by replacing the liquid distilled by distillation with pure alcohol. The disadvantage of this method is the use of pure alcohol and acid anhydride as a raw material, which significantly increases the cost of the obtained ester, as well as the process at sufficiently high temperatures of 160-240 ° C due to the use of titanium catalysts.

Closest to the proposed technical essence and the achieved effect is a method for producing a mixture of esters and / or mixtures thereof (RF Patent No. 2127722, publ. 03.20.1999, С07С 67/08, С07С 69/14). This invention provides a method for the synthesis of esters of alcohols by esterification with organic acids at a temperature of 60-130 ° C, in the presence of a catalyst - cation exchange resin type KU-2, pre-treated with sulfuric acid at a rate of 5-20 wt.%, And before separation of the two phases, the reaction mixture is cooled to a temperature of (-2) - (- 5) ° C, and waste from the production of vinyl acetate and alcohols is used as the feedstock. This method shows good results in the yield of the product, the final product has a relatively inexpensive cost, and also not a large consumption of catalyst.

The disadvantage of this method is the rather long time of the esterification process (2-4 hours), as well as the need for pre-heating the reaction mixture and subsequent control of the reaction temperature in order to avoid its overheating.

The objective of the present invention is to develop a method for producing esters from the waste products of caprolactam, with the aim of intensifying the process of synthesis of esters, expanding the existing raw material base and reducing the cost of the product by reducing the cost of controlling the reaction temperature.

To achieve this goal, a method for producing esters from caprolactam production wastes is proposed.

The problem is solved in that the method for producing esters from caprolactam production wastes is carried out by the esterification reaction of organic acid and alcohol at a temperature of 40-130 ° C using a cation exchange resin pre-treated with sulfuric acid in an amount of 0.4-2% mass from the mass of loaded raw materials with cooling the reaction mixture before the separation of the two phases. In contrast to the prototype, in the claimed method, the esterification reaction is carried out under conditions of autocatalytic heat generation supporting the esterification reaction, and alcoholic waste products of caprolactam production containing 60-70% n-amyl alcohol, 5-10% isoamyl alcohol, are used as raw materials % inert impurities.

The essence of the invention is as follows. Caprolactam (SFC) wastes containing alcohols in a batch reactor are used as feedstock and are contacted with organic acids in the presence of a catalyst at a temperature of 40 to 130 ° C, which is maintained due to the balance of the heats of the chemical reaction and the heat necessary to maintain the temperature . The contact time is 1.5-2 hours, the catalyst is a cation exchange resin in an amount of 2 wt.%.

In the process of synthesis of esters, a cation exchange resin acts as a catalyst. To increase the catalytic properties of the resin, it must be activated. The activating agent is sulfuric acid H ₂ SO ₄ , in an amount of 15-20 wt.% By weight of the resin. This helps to increase the rate of the esterification reaction due to the activation of additional acid sites. The activation process is 12 hours. Then the cation exchange resin is washed with distilled water to pH = 6-7. Then it is dried at a temperature of no more than 30 ° C. After that, the cation exchange resin is ready for use.

After synthesis, the catalyst must be regenerated. For regeneration (transfer of spent cation exchanger to the H-form), it is washed with a solution of sulfuric acid. When using sulfuric acid, we carry out stepwise regeneration with a gradual increase in the acid concentration to (1-6%). The specific consumption of acid is 140-160 g / mol of absorbing ions. Water consumption for washing 5 vol./about. cation exchanger.

The invention is illustrated by the following examples.

Example 1

Preparation of Amyl Formate 900 g of alcoholic caprolactam production waste containing (60-70% n-amyl alcohol, 5-10% iso-amyl alcohol, 20-35% inert impurities), 10 g of catalyst (KU-2-8 cation exchange resin, pretreated with sulfuric acid), after which 322 g of formic acid are poured into the reactor at such a rate that the temperature of the reaction medium is maintained at 60 ° C. As a result of the reaction, a reaction mixture was obtained for 2 hours, which was subjected to fractional distillation.

Thus, the method allows to obtain amylformate with a yield of 73.1% wt. and additionally obtain useful heat emission at the level of 6743.8 kJ (Data are presented in Table 1).

Example 2

Getting amyl acetate. 900 g of alcoholic caprolactam production wastes were loaded into the reactor, containing (60-70% n-amyl alcohol, 5-10% iso-amyl alcohol, 20-35% inert impurities), 10 g of catalyst (KU-2-8 cation exchange resin, pretreated with sulfuric acid), after which 420 g of acetic acid is poured into the reactor at such a rate that the temperature of the reaction medium is maintained at 65 ° C. As a result of the reaction, a reaction mixture was obtained for 2 hours, which was subjected to fractional distillation. Thus, the method allows to obtain amyl acetate with a yield of 80.3% wt. and additionally obtain a useful heat release at the level of 7286 kJ (Data are presented in Table 2).

Thus, the proposed technical solution allows to intensify the process of synthesis of esters, expand the existing raw material base and reduce the cost of the product by reducing the cost of ensuring control of the reaction temperature.

Table 1 Heat balance of the esterification reaction The thermal effect of chem. reaction, kJ Heat absorption to maintain T, kJ Heat dissipation, kJ 6800 56.2 6743.8

table 2 Heat balance of the esterification reaction The thermal effect of chem. reaction, kJ Heat absorption to maintain T, kJ Heat dissipation, kJ 7396 109.3 7286.7

Claims (2)

1. A method of producing esters from caprolactam production wastes by the esterification reaction of an organic acid and alcohol under conditions of autocatalytic heat generation supporting an esterification reaction at a temperature of 40-130 ° C. using a cation exchange resin pretreated with sulfuric acid in an amount of 0 as a catalyst 4-2 wt.% From the mass of the loaded raw materials with cooling of the reaction mixture before the separation of the two phases. 2. The method according to claim 1, characterized in that the alcohol wastes of caprolactam production containing 60-70% n-amyl alcohol, 5-10% iso-amyl alcohol, 20-35% inert impurities are used as raw materials.