Method for recovering phosphorous acid by acidolysis of dimethyl phosphite distillation residual liquid

Abstract

The invention discloses a method for recovering phosphorous acid by acidolysis of dimethyl phosphite distillation residual liquid. Dimethyl phosphite residual liquid is subjected to the steps of filter pressing, acidolysis, secondary acidolysis concentration, crystallization, material washing and the like to obtain phosphorous acid. In the method for recovering phosphorous acid by acidolysis of dimethyl phosphite distillation residual liquid, phosphorous acid is recovered by combination of high-temperature distillation and temperature-lowering crystallization, the recovery efficiency is high, and the existing chloromethane recovering device is utilized for recovering chloromethane during the recovery process of phosphorous acid, and therefore, the recovery benefit is further enhanced.

Description

technical field [0001] The invention relates to a method for recovering phosphorous acid, in particular to a method for recovering phosphorous acid through acidolysis from dimethyl phosphite distillation raffinate. Background technique [0002] In the production process of dimethyl phosphite, dimethyl phosphite residue will be produced as a by-product. For example, a dimethyl phosphite production device with an actual production capacity of 35,000 tons will by-produce 3,500 tons of dimethyl phosphite residue per year (10 : 1 ratio), which mainly contains 75-85% phosphorous acid and about 5% dimethyl phosphite. For the production residue, if it is treated in an environmentally friendly way, it will be very difficult to deal with; if it is directly sold as waste, it will lose a lot of sales revenue and may leave environmental protection risks. For the recovery of dimethyl phosphite residue, the current manufacturers mainly adopt the method of hydrolysis, but because the metha...

AI Technical Summary

Problems solved by technology

For the production residual liquid, if it is treated in an environmentally friendly way, it is very difficult to deal with it; if it is sold directly as waste, it will lose a lot of sales revenue and may leave environmental protection hazards

For the recovery of dimethyl phosphite residue, the current manufacturers mainly adopt the method of hydrolysis, but because the methanol solution produced by hydrolysis still needs to be rectified before it can be used continuously, the recovery cost is relatively high