SU364597A1 - METHOD OF OBTAINING L1ETHYLMETHACRYLATE - Google Patents

Description

The invention relates to methods for producing methyl methacrylate, the most important monol of the methacrylic series, widely used for the production of organic glass and other polymers and copolymers.

A known method for producing methyl methacrylate by mixing methacrylamide sulfate (obtained from acetone cyanohydrin) with water and methanol. The esterification process is carried out in a reactor. Subsequently, their apparatuses complete the esterification process and distil the reaction products.

The disadvantage of this method is that in tank reactors it is very difficult to distill off the reaction products from the mother liquor, which is a concentrated solution of sulfuric acid and ammonium bisulfate, which makes it necessary to maintain the reaction mass in a relatively high temperature zone (90-140 ° C) within 6-8 hours As a result, partial polymerization and tarification of methyl methacrylate occurs, which reduces the yield of the target product and complicates operation due to the need to clean the apparatus and communications.

In addition, this instrumentation process does not significantly increase the capacity of the unit, since an increase in reactor capacity leads to a deterioration of the conditions for the distillation of reaction products, i.e., an increase in the power of the unit reduces the yield of the target product per unit of raw material.

In order to intensify the process according to the proposed method, the distillation of the target product is carried out by heating to.

The process of saponification and esterification of methacrylamide sulfate is carried out in a reactor and a tubular sectional film apparatus,

equipped with a reflux condenser, a target fraction condenser and a tail condenser. A melting fraction condensed in a reflux condenser, enriched in part by methacrylic acid formed in the process,

return to the distribution device of the upper section of the film apparatus, where it is mixed with the reaction mixture coming from the reactor, and the light boiling tail fraction enriched in methanol is returned

iia lower section switchgear. The process in the film apparatus is carried out at 120-160 C.

Such a system allows to intensify the process of doeterification and distillation of reaction products, since in the film mode the most favorable conditions for heat transfer and mass transfer between the flowing reaction mass enriched with methacrylic acid and rising are created.

methanol vapor, and carrying out the process at

a higher temperature makes it possible to finish it in a time equal to the time that the film runs off but on the tubes.

The proposed method allows creating sick power units for the production of methyl methacrylate.

The method is carried out in the following way.

Methacrylamide sulfate, obtained in the previous stage of the process, methanol and water are continuously fed into the reactor with a stirrer and a cooling jacket. The heat of the esterification reaction is removed by cooling off the walls of the apparatus, as well as by evaporation of part of the volatile components, which after condensation are returned to the reactor. Time reakd1 and 1 hour. The reaction mass continuously flows to the distribution device of the nerve section of the film apparatus, where it is distributed along the walls of the tube space and flows down. The tubes are heated with saturated water vapor entering the annular space.

In a thin film of the reaction mass flowing down the tubes, the evaporation of reaction products, formed in small amounts of dimethyl ether and methacrylic acid and supplied in an excess of methanol and water, as well as mass transfer between the liquor and liquid phases, occurs. The vapors leaving the film apparatus are cooled to 82 ° C in a reverse condenser. In this case, the main amount of distilled methacrylic acid condenses. Then a fraction of methyl methacrylate with impurities of water and methanol is condensed in a separate condenser 82–70 ° C, and uncondensed vapors (mainly methanol) are sent to the tail condenser, the condensate from which enters the lower section of the tubular apparatus, where it evaporates; the vapors formed, interacting with the flowing film of the reaction mass, enter into an esterification reaction with duthacrylic acid and methacrylamide to obtain the desired product.

The target fraction, methyl methacrylate starch (MMA), is sent for purification from impurities in order to obtain a finished monomer of the required quality. The residence time of the reaction mass in the nlenochny apparatus is not more than 30 minutes, in the reactor - up to 1 hour.

P r and m er. The reactor continuously receives 1567 g / h of the reaction mass from the stage of producing methacrylamide sulphate containing (in g / h): 521.7 100% methacrylamide, 375 water and 275 methanol. 690 g / h of washed methyl methacrylate raw are obtained, including 100% MMA 573 g / h. The output of MiMA methacrylamide 93%.

PREED MET OF INVENTION

Claims (2)

1. A method of producing methyl methacrylate by displacing methacrylamide sulfate with lethanol and water, characterized in that, with the aim of hydrogenation of the process, the distillation of the target product is carried out by heating to 160T. 2. A method according to claim 1, characterized in that the stripping is carried out in a tubular sectional palletizer.