Technology for preparing diethyl phosphite by by-product of triethyl phosphite

Abstract

The invention relates to a technology for preparing diethyl phosphite by by-product of triethyl phosphite, belonging to the field of a preparation technology of diethyl phosphite. The method utilizes the by-product generated in the production of the triethyl phosphite to react with phosphorous acid, and the diethyl phosphite in the by-product of the triethyl phosphite can be recycled; the product is high in yield and good in purity, the equipment investment is less and the production cost is low; and the technology has the characteristics of being less in emission load of waste gas and waste water, environment-friendly and the like. According to the technology, the whole production process can be completed by one set of acid mixing kettle, one set of synthesis kettle and one set of rectifying tower, so that a production device is simple, the production capacity is high, the equipment investment is less, the operation is simple, and the production efficiency is high. The technology is low in consumption and high in yield. The distillate on the top of the tower and the high boiling point material discharged from the bottom of the tower can be recycled in the acid mixing kettle, so that air pollution and waste water are not generated in the whole production process, and the sewage treatment cost is very low. The technology solves the problems that the existing triethyl phosphite production technology is complicated, low in product yield, higher in energy consumption and higher in production cost.

Description

technical field [0001] The invention relates to a process for preparing diethyl phosphite by using triethyl phosphite by-product, and belongs to the technical field of diethyl phosphite preparation. Background technique [0002] Now the domestic production of triethyl phosphite has reached 20,000 tons per year. As a by-product of triethyl phosphite, diethyl phosphite is mainly composed of 60-70% triethyl phosphite, % diethyl phosphite and 8-10% ethanol, because the boiling points of triethyl phosphite and diethyl phosphite are relatively close, their boiling points are 156.5°C and 187°C respectively, and it is difficult to separate them with a tower due to their similar boiling points , so the old process cannot recycle the triethyl phosphite and diethyl phosphite. According to statistics, about 500 tons / year of by-products of triethyl phosphite are waiting for biochemical treatment as waste, which brings certain harm to the surrounding environment. influences. [0003] An...

AI Technical Summary

Problems solved by technology

The advantage of the non-solvent method is that the reaction speed is fast and the product yield is high; the disadvantage is that because phosphorus trichloride contains a certain amount of free phosphorus, when a certain accumulation is reached in the production process, a fire accident will occur when it encounters ethanol, so It is required that the purity of phosphorus trichloride must be high, the content of free phosphorus must be controlled within a certain range, and the synthesis reaction temperature is required to be low. The synthesis reaction temperature is generally controlled at 6-8 degrees, and the yield of the product can reach 90% (according to Phosphorus trichloride yield), the finished product diethyl phosphite content is less than 98%, and the stability is poor

In addition, when the residual liquid is recovered and re-distilled, the temperature must be well controlled. If the temperature is over-heated, there may be a danger of decomposition and explosion under negative pressure, and a large amount of C will be produced at the same time. 2 h 5 Cl and HCl gas requires a lot of anti-corrosion equipment and energy consumption to recover, which pollutes the environment more

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