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Separation of the Ternary System of Methanol-Dimethyl Carbonate-Ammonia

Author: ZhengJinFeng
Tutor: YuanCunGuang；YuJianFeng
School: China University of Petroleum
Course: Applied Chemistry
Keywords: Dimethyl carbonate Separate Methanol Ammonia Salting Distill Extractive distillation
CLC: TQ028
Type: Master's thesis
Year: 2008
Downloads: 213
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Abstract

This paper mainly studied the separation and purification problems of the reaction product prepared by the urea - methanol homogeneous catalysis method, dimethyl carbonate (DMC) \Above reaction system DMC-Mt (methanol)-NH3 ternary mixture distillate liquid as the research object, through a large number of experimental studies, complete by heating reflux prolapse ammonia the DMC-Mt-NH3 ternary mixtures, the solution in the large amount of ammonia is reduced to 0.026 mol? L-1; then deaminase DMC-Mt binary mixed solution was obtained by distillation DMC mass concentration of 30% of DMC-Mt Azeotrope; turn of this two yuan DMC the azeotropic system in the concentration and separation experiments. This paper determines the DMC-Mt binary azeotropic system separate ways, with anhydrous CaCl2 as the salting reagents with salt distillation and extractive distillation method with 37.45% CaCl2 aqueous solution as extractant, and to study the corresponding experimental conditions. (1) obtained by reaction of urea - methanol homogeneous catalysis of distillate liquid product that DMC very low content of DMC-Mt-NH3 ternary mixture solution was heated to boiling under reflux for 2 h the system can be more than 90% of the dissolved ammonia prolapse. Ternary mixture solution dissolved ammonia content in excess of 0.1 mol · L-1 reaction or absorption of dilute hydrochloric acid solution, measured back titration with NaOH standard solution. (2) study the equilibrium phase diagram of the the DMC-Mt binary Azeotrope data base to provide a theoretical basis and the experimental conditions for the subsequent concentration and separation of DMC. (3) for the concentration and separation of the DMC content of about 30% of DMC-Mt Binary Azeotrope first salt distillation methods, selected from a wide choice of salting agent anhydrous of CaCl2; under atmospheric pressure 2 h before, after a heated environment (water bath) temperature of 80 ° C to reflux for 30 min, continuous linear warming (10 ℃ / 2h), the distillate flow control \distillate, the obtained DMC content of 50% methanol solution. Anhydrous CaCl2 was used in the experiment can be reused after a heat treatment and activation, the effects of salting substantially constant. Another method is concentrated and separated (4) DMC content is about 30% of DMC-Mt binary azeotrope system CaCl2 aqueous solution as an extraction agent, extraction and distillation method, is determined by experiments of CaCl2 suitable concentration of 37.45%, a suitable solvent is water . The extractant solution with DMC-Mt Binary Azeotrope solution volume ratio of 1:1, the extract can be recycled. 37.45% CaCl2 aqueous extraction agent heated in advance to 65 ℃, the rate of \The rate receiver distillate. The temperature is 80 ℃ the initial heated environment (water bath) and was warmed to 90 ° C to 10 ° C / 2h linear charge 2 h before the distillate obtained DMC content of 55% of the distillate. (5) the salt distillation with salt water as solvent extraction and distillation methods, advantages and disadvantages are analyzed and compared. Extractive distillation process take once the DMC concentrated distillation experiments the effect DMC-Mt binary system, select appropriate conditions extractive distillation process is taken under the appropriate conditions distillation can get DMC, methanol completely separated forecasts.

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