Method for preparing triethyl phosphate

Abstract

The invention discloses a method for preparing triethyl phosphate, which is characterized by comprising: a step of esterification, which is to react phosphorus oxychloride with ethanol according to a molar ratio of the phosphorus oxychloride to the ethanol of 1:(1-5) in a jacket type cooling and stirring container set, obtain the mixture of ethanol and hydrogen chloride which are volatile components, condense the mixture in a reflux condenser, and absorb the incondensable volatile hydrogen chloride component by a washing tower circulating membrane absorption unit; a step of dealcholization and dehydrochlorination, which is to fill the reaction mixture obtained after esterification into a degassing distillation tower, remove the volatile components, namely ethanol and hydrogen chloride, in the reaction mixture, separate the excessive ethanol and hydrogen chloride, which are obtained from esterification materials, from triethyl phosphate, mainly obtain 95-to-98.5-weight-percent triethyl phosphate from the bottom of the degassing distillation tower, and obtain 99.99-percent triethyl phosphate and 67-percent diethyl phosphateby rectifying and separating; and a step of hydrogen chloride absorption, which is to introduce the hydrogen chloride gas obtained in the esterification and the hydrogen chloride gas from dealcholization and dehydrochlorination into a washing tower circular tube falling absorption unit, and producing 31-percent hydrochloric acid.

Description

technical field [0001] The invention relates to the technical field of fine chemicals, and relates to a method for preparing triethyl phosphate by reacting phosphorus oxychloride and ethanol. Background technique [0002] Triethyl Phosphate is used in a very wide range of applications such as auxiliary in textiles and paper products, plasticizer in plastics and coatings, non-reactive flame retardant, hardener and accelerator, lubricant, flotation agent, defoamer, emulsifier, stabilizer or extractant. [0003] Existing methods for preparing triethyl phosphate from phosphorus oxychloride, also known as phosphorus oxychloride and corresponding ethanol reaction, all adopt esterification reaction, dealcoholization reaction, alkali neutralization reaction and crude distillation, and then fine distillation to prepare phosphoric acid triethyl ester. Usually all try to improve the preparation method from the reaction temperature, the ratio of the raw material phosphorus oxychloride...

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Problems solved by technology

[0004] The measure adopted for removing hydrogen chloride in the existing preparation method is that phosphorus oxychloride reacts with ethanol under reduced pressure and elevated temperature, so that the reaction mixture is continuously removed hydrogen chloride. Afterwards, hydrogen chloride is absorbed by ethanol again, and reclaiming ethanol to participate in the secondary esterification reaction has affected the reaction conversion rate again; Use raising temperature to remove hydrogen chloride, cause a certain amount of high-boiling phosphoric acid to produce again, make reaction material can cause pyrolysis during distillation, also not It is beneficial to the production of triethyl phosphate, resulting in a considerable amount of ethanol loss; the use of alkali neutralization reaction reduces the space-time yield of hydrogen chloride and phosphoric acid in the mixed material, although the use of alkali neutralization reaction avoids the acidity of the reaction product solution, and the neutralization of the reaction mixture has increased the cost of the neutralizer alkali, and also produced a large amount of waste water, and the up-to-standard treatment of the waste water has increased the production cost; especially for triethyl phosphate, because ethanol, water and triethyl phosphate are completely Miscible, especially difficult to handle, ethanol must be distilled off from the water phase and triethyl phosphate extracted from the water phase, which results in a large loss of product, ethanol extractant