| 简介 |
FIELD : chemistry.SUBSTANCE : invention relates to an ester saponification method and a method of recycling sodium salts when producing caprolactam, as well as apparatus for realising said methods. The saponification method involves processing a reaction liquid which contains cyclohexane, cyclohexanone, cyclohexanol, cyclohexyl hydroperoxide, esters and organic acids, and involves distillation of the reaction liquid with separation of a portion of recycled cyclohexane, mixing the still liquor with a neutralising agent, neutralisation and saponification of the obtained mixture with separation of the organic layer and aqueous solution of sodium salts of organic acids, distillation of the neutral cyclohexane, drying the ketone-alcohol mixture with separation of cyclohexane and feeding said cyclohexane to the step for distillation of neutral cyclohexane, rectification of the dried ketone-alcohol mixture with separation of cyclohexanone, and thermal decomposition of sodium salts of organic acids. After distillation of the neutral cyclohexane, the still liquor undergoes re-saponification with addition of fresh alkali and further separation of sodium salts of organic acids and unreacted aqueous alkali solution, fed to the first saponification and neutralisation step. The resultant stream of solutions of sodium salts of organic acids is fed for thermal decomposition to form a melt of calcined soda containing 93-95% Na2CO3 and 5-7% NaOH, which, in form of a solution with concentration of 11-17%, is fed as a neutralising agent to the first saponification and neutralisation step. The apparatus for recycling sodium salts of organic acids is fitted with a unit for dissolving the molten soda, which consists of two sections with an overflow gate in between, one of the sections being connected to a unit for feeding chemically purified water and fitted a steam bubbler, and the second section being fitted with a solution outlet into a balance tank with recirculation of the excess into the dissolution unit, and the balance tank is fitted with an outlet into the mixer for mixing the still liquor with the solution of the neutralising agent of the ester saponification apparatus and with recirculation of the excess into the balance tank.EFFECT : improved methods for saponification of esters and recycling sodium salts when producing caprolactam.12 cl, 3 dwg, 2 ex |
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