Method for continuous production of high-concentration methylal

Abstract

The invention relates to a method for continuous production of high-concentration methylal. The method is characterized by adopting methanol and formaldehyde for feeding respectively, controlling the content of each of formaldehyde and the methanol in each reactor and enabling the lowermost side reactor to adopt the process of enabling reactants of feed material of an upper-stage column plate to enter a lower-stage column plate; and the method comprises the following steps: a) a reaction rectification column is a packed column, formaldehyde is fed at the upper part of the reaction section, and methanol is fed through an inlet of the uppermost side reactor and the inlet of the lowermost side reactor; b) the reaction temperature of the side reactors is 60-80 DEG C from top to bottom, and liquid-phase reaction is performed on methanol and formaldehyde in the reactors to generate methylal; c) except for the lowermost side reactor, each reactor adopts the way of enabling extracted liquid from the lower-stage column plate of the rectification column to enter the reactor, and enabling reactor products to enter the upper-stage column plate of the rectification column; d) the lowermost side reactor adopts the way of enabling the extracted liquid from the upper-stage column plate of the rectification column to enter the reactor and enabling the reaction products to enter the lower-stage column plate of the rectification column; and e) the gas phase at the top of the column is condensed, then part of the condensed gas phase refluxes into the rectification column, and the other part of the condensed gas phase is extracted and introduced into a methylal intermediate storage tank; and liquid discharged from a column kettle is returned into a formaldehyde preparation unit for recycling or discharged after the liquid is treated to achieve the standard.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, and is a method for continuously producing high-concentration methylal; in particular, a process for synthesizing methylal using a catalytic reaction rectification tower as a reaction device. Background of the invention [0002] Methylal is an important downstream product of formaldehyde, and its production methods and application technologies are constantly being developed and improved. Especially in today's increasingly tense petroleum resources, methylal, as one of the important downstream derivatives of methanol, has been widely used in methanol-based fuels, oil additives, fuel cells and liquid fuels in addition to being used as a solvent. All have attracted widespread attention at home and abroad. [0003] Initially, the laboratory prepared methylal by heating formaldehyde and methanol in the presence of concentrated sulfuric acid and other liquid acids. The industrial production...

AI Technical Summary

Problems solved by technology

The main disadvantages of this method are: low reaction efficiency, high loss of raw materials, excessive formaldehyde and methanol in wastewater and difficult to handle

[0005] Affected by the balance of methanol-methylal-formaldehyde-water vapor-liquid, it is difficult to control the concentration of methylal to be higher than 98% and to control the content of formaldehyde and methanol in the tower bottom discharge liquid to less than 200ppm by using the above two reactive distillation towers

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