Process for continuously generating methyl acetate by reactive distillation taking ionic liquid as catalyst

Abstract

A process for continuously generating methyl acetate by reactive distillation taking ionic liquid as a catalyst is as follows: raw materials are preheated, acetic acid is input from the upper segment of a reactive distillation tower, ionic liquid is input from the central segment of the tower and methanol is input from the lower segment of the tower simultaneously, the central segment of the reactive distillation tower is a reaction zone, the product of methyl acetate is extracted from the top of the tower, the catalyst of ionic liquid is extracted from the bottom of the tower and enters a flash drum for flash evaporation, the liquid extracted from the bottom of the flash drum is the catalyst of ionic liquid which returns to the reactive distillation tower, gas phase evaporated from the flash drum is mixed vapour of water and methanol, which is input to a methanol recovery tower, raw material of methanol is extracted from the top of the methanol recovery tower after being separated, and returns to the reactive distillation tower to be raw material, water is extracted from the bottom of the methanol recovery tower and is discharged. The process of the invention discharges no waste acid water, the material of devices of the required towers is only 316L stainless steel and can reduce the corrosion for the devices and one-time investment remarkably, energy consumption decreases by more than 15% simultaneously, therefore the production cost of final product reduces by more than 30%.

Description

technical field [0001] The invention relates to a new process for producing methyl acetate by reactive distillation using ionic liquid as a catalyst, which is characterized in that ionic liquid is used as a catalyst to organically combine with an ordinary rectification tower to form a reactive distillation coupling process, and the production purity is more than 99.9%. methyl acetate. Background technique [0002] Catalytic distillation is a chemical operation process that integrates reaction and distillation in the same equipment. Compared with traditional distillation process, it has many advantages such as low production energy consumption, high reaction conversion rate, and reduced one-time investment of equipment. In recent years, catalytic distillation technology has received extensive attention and research, and has broad potential application prospects in processes such as etherification, alkylation, esterification, dehydration and hydration. But looking at the appl...

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Problems solved by technology

For example, Chinese patents CN1405140 and CN1554638 propose methylimidazolium tetrafluoroborate ionic liquids to replace concentrated sulfuric acid and hydrofluoric acid that pollute the environment for esterification reactions, but the catalytic effect is general, and the synthesis methods of ionic liquids are complex and expensive, and difficult to scale Production

Chinese patents CN101024612A and CN101255111A propose to use ionic liquid α-pyrrolidone bisulfate as a catalyst for continuous esterification reaction to produce ethyl acetate. The problem with this method is that ionic liquid α-pyrrolidone bisulfate is easily decomposed when it meets water, resulting in its esterification The essence of the chemical reaction is sulfuric acid catalysis, the recovery and recycling of the catalyst is troublesome, and it will still cause corrosion of the equipment

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