CS239263B1 - Production method of epihydrochloride - Google Patents

Abstract

The purpose of the invention was a method of processing waste from the rectification of crude epichlorohydrin during its production. The purpose was achieved by the production method of the epichlorohydrin according to the invention so that it is distillation residue from crude rectification epichlorohydrin is separated by water vapor at atmospheric pressure to distillate and the remainder containing aqueous and organic phases, aqueous the residue and distillate phases are separated and added into the dehydrochlorination process, left over the distillate is separated into water by rectification, trichloropropane and epichlorohydrin which is dosed to the production stage of epichlorohydrin, where dehydrochlorination and / or crude takes place epichlorohydrin.

Description

The invention relates to a process for the preparation of epichlorohydrin. The most commonly used industrial process for the production of epichlorohydrin is based on chlorination of propene, chlorohydrination of the resulting 3-chloropropene, dehydrochlorination of the resulting mixture of dichloropropanols and subsequent rectification of crude epichlorohydrin.

The rectification of the crude epichlorohydrin yields a distillation residue consisting predominantly of the byproducts of trichloropropane and tetrachloropropyl ether, the unreacted raw materials 1,2 to 1,3 dichloropropane and the epichlorohydrin product, the content of which depends on the sharpness of the separation at rectification.

The disadvantage of the existing process for the production of epichlorohydrin is that the waste from the rectification of crude epichlorohydrin containing valuable raw materials is disposed of by incineration not only here but also in the world, because its separation has been considered technically difficult and uneconomical.

This disadvantage is overcome by the process for producing epichlorohydrin by chlorination of propene, chlorohydrination of the resulting 3-chloropropene, dehydrochlorination of the resulting mixture of dichloropropanols and subsequent rectification of crude epichlorohydrin according to the invention by separating the distillation residue from rectification of crude epichlorohydrin. the aqueous and organic phases, the aqueous phases of the distillate and the residue are separated and added to the dehydrochlorination of the manufacturing process, the remaining distillate is rectified into water by trichloropropane and epichlorohydrin which is fed to the epichlorohydrin production step where dehydrochlorination is carried out.

The advantages of the process for the production of epichlorohydrin according to the invention reside in the recovery of waste and in an increase in the yield of production of epichlorohydrin. The separated mixture containing predominantly trichloropropane can advantageously be further used as a feedstock for the pyrolysis chlorination in the production of chlorinated solvents or directly as a solvent.

Example 1

A distillation residue from the distillation of crude epichlorohydrin of the composition shown in Table 1 at a rate of 0.5 kg / h was continuously fed to a 5 th floor rectification column 1. At the same time as the distillation residue was injected, 2.0 kg / h of water vapor was fed to the bottom of the column and 1.3 kg / h at the 20 th floor.

The column was operated at atmospheric pressure. Further, a portion of the organic phase of 1.0 kg / h, recovered from the common distillate leaving column 1 and column 2, also of 20 trays, was returned to the 20th tray to dewater and remove epichlorohydrin from trichloropropane.

The distillation residue leaving the bottom of column 1. was continuously separated into aqueous and organic phases. The average aqueous phase flow rate was 2.2 kg / h, the organic phase flow rate was 0.064 kg / h.

The aqueous phase contained 1.06 wt. dichlorohydrins and was dosed to the dehydrochlorination stage of epichlorohydrin production, the composition of the organic phase of the distillate was cont. injected into the column 2 at 1.2 kg / h where epichlorohydrin and water were separated from the organic phase.

Dewatered trichloropropane containing less than 0.1 wt. epichlorohydrin at an average rate of 0.407 kg / h. The aqueous phase of the distillate continuously separated from the organic phase did not contain dichlorohydrin, flowed off at a rate of 1.1 kg / h and contained 0.55% by weight. epichlorohydrin and was added to the crude epichlorohydrin.

Table 1

% wt. ECH TCP 1,2 DCH 1,3 DCH TCPE composition of the spray 1,21 86.44 4.66 0.84 6.85 Composition of org. residue phase - 39.62 3.93 2.52 53.93

Example 2

A distillation residue from the distillation of crude epichlorohydrin at an average rate of 110 kg / h of the composition shown in Table 2 was continuously fed to the 10 th floor rectification column on the 10 th floor. 2 with the simultaneous supply of 400 kg / h of steam to the column, water to the 31st floor at a flow rate of 200 kg / h and a portion of the organic phase of the distillate at a flow rate of 220 kg / h, obtained by cont. by separation from the aqueous phase after the condensation of the vapors exiting the column 7 was continuously separated into aqueous and organic phases.

The average flow rate of the organic phase of the heel product was 13.93 kg / h with the average composition shown in Table 2, the flow rate of the combined aqueous phases of the distillate was 600 kg / h on average and contained an average of 0.72% by weight. dichloromethane and 0.24% epichlorohydrin.

The remaining portion of the organic phase distillate of the average composition shown in Table 2 was collected in a 20-tray column 2 digester. The column 1 was operated for 126 hours, during this time 11 607 kg of the organic phase of the distillate from the column 1 were recovered and stored in the column boiler 2.

The organic phase from column 1 was dewatered by discontinuous rectification on column 2. At the same time epichlorohydrin was separated from it. 507 kg of distillate containing 310 kg of trichloropropane, 91 kg of epichlorohydrin and 106 kg of water were recovered and added to the crude epichlorohydrin to produce epichlorohydrin and 11 kg of a reboiler product of the composition shown in Tab. 2, which contained 0.0005 wt. water and was added as feedstock to the feed of high temperature pyrolysis chlorination of propylene.

Table 2

% wt. ECH TCP 1,2 DCH 1,3 DCH TCPE injection into column 1 1.93 83.91 3.83 1.07 .8,43 org. residue phase - 25.85 4.67 2.89 66.59 org. distillate phase 0.81 99.15 0.03 0.01 - cooker prod. col. 2 0.01 99.95 0,03 ' 0.01 -

SUBJECT OF THE INVENTION

Claims (1)

A process for the preparation of epichlorohydrin by chlorination of propene, chlorohydrination of the resulting 3-chloropropene, dehydrochlorination of the resulting mixture of dichloropropanols and subsequent rectification of crude epichlorohydrin, characterized in that the distillation residue from rectification of crude epichlorohydrin is separated by atmospheric steam under atmospheric pressure the aqueous phases of the distillate and residue are separated and added to the dehydrochlorination of the manufacturing process, the remaining distillate is rectified into water, trichloropropane and epichlorohydrin which is fed to the epichlorohydrin production stage where dehydrochlorination is carried out and / or crude epichlorohydrin.