Reactive distillation device and method for separating and purifying methylal

Abstract

The invention relates to a reactive distillation device and method for separating and purifying methylal. The device mainly comprises a reactor / agitator, a distillation column, a condenser, a reflux ratio controller, stainless steel fillers, a temperature gauge, a pressure gauge and a product collection and storage tank. The methylal is synthesized by subjecting the raw materials including methanol and formaldehyde to react and is separated and purified. After the methylal product is extracted, the distillation column is continuously used for separating and recovering the methanol and is usedfor the next cycle, thus improving the utilization ratio of the raw materials. The methanol is added to the reactor by one step. The problem that the product purity fails to meet the requirement due to azeotropy of the methanol and the methylal can be solved through the operation mode of feeding the formaldehyde from the top of the distillation column. The concentration of the formaldehyde in theresidual liquid in the reactor conforms to the effluent standard. Through the operation mode of carrying out reaction and separation separately, the adverse effects of difficult control and difficultfilling of catalysts caused by inconsistence of the reaction conditions and the separation conditions can be overcome and the operation difficulty of reactive distillation can be reduced, thus expanding the application range of reactive distillation.

Description

technical field [0001] The invention relates to a reactive distillation device and method for separation and purification of methylal. Specifically speaking, it is a new type of intermittent reactive distillation operation mode and realization method that uses methanol and formaldehyde as raw materials to synthesize methylal and then separates and purifies it. After the production of the methylal product is completed, the rectification tower continues to be used for the separation and recovery of methanol for the next cycle, which improves the utilization rate of raw materials. Methanol is added to the reactor at one time, and formaldehyde is fed from the top of the rectification tower to solve the problem that the purity of the product cannot meet the requirements due to the azeotropy of methanol and methylal, and the concentration of formaldehyde in the residual liquid of the reactor meets the emission standards. The separate operation mode of reaction and separation can ov...

AI Technical Summary

Problems solved by technology

In foreign countries, there have been industrial applications for the production of methylal by knapsack reactive distillation, which is suitable for large-scale continuous reactive distillation processes, but this technology has not been used in China

[0007] Although the process of reactive distillation has been continuously improved, it still has its own limitations: high requirements on the reaction system, reaction and distillation separation must be carried out at the same temperature and pressure, and the volatility of the target product and reactant cannot be similar , at the rectifying temperature, it will lead to adverse effects such as the increase of side reactions; the chemical reaction must be a liquid phase reaction, the catalyst used in the catalytic rectification process cannot be miscible or interact with the components of the reaction system, and the raw materials cannot contain catalyst poisons It is not suitable for the petrochemical process that is easy to coke on the catalyst during the reaction; in addition, the catalyst must have high activity and long life in the rectification temperature range, and its packing method will also have a great impact on rectification

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