Continuous synthesis technique of hydroxyethylidenediphosphonic acid

Abstract

The invention relates to a continuous synthesis technique of hydroxyethylidenediphosphonic acid, which comprises the following steps: 1. mixing raw materials: mixing phosphorus trichloride and acetic acid in a mol ratio of 1:(2.8-3.0) in a mixing kettle; 2. sending the mixture into a tubular reactor: pumping the mixture into the tubular reactor through a diaphragm pump; 3. carrying out esterification reaction while controlling the temperature of the tubular reactor at 70-130 DEG C; 4. separating the reaction mixture in a gas-liquid separator for recycling; 5. carrying out hydrolysis reaction to obtain the hydroxyethylidenediphosphonic acid; and 6. distilling out acetic acid under negative pressure to separate the acetic acid from the product, wherein the acetic acid enters an acetic acid storage tank as a raw material. In the invention, the hydroxyethylidenediphosphonic acid is continuously produced in a semi-closed system, thereby changing the existing intermittent production mode and enhancing the production efficiency; and the invention overcomes the defects of low product yield, too many side reactions and high contents of phosphorous acid and phosphoric acid in other preparation techniques, and implements complete cyclic utilization of acetic acids with different concentrations.

Description

technical field [0001] The invention belongs to the technical field of industrial water treatment, and in particular relates to a production method of an organic phosphine water treatment agent. Background technique [0002] Hydroxyethylene diphosphonic acid (HEDP) is widely used as a water treatment agent (water quality stabilizer) in industrial circulating cooling water systems. It has good scale and corrosion inhibition, and is an anionic corrosion inhibitor. Its oxidation resistance is better than that of aminotrimethylene phosphate (ATMP) and ethylenediaminetetramethylene phosphate (EDTMP), and it decomposes at 250°C. . It has a good effect on inhibiting calcium carbonate, hydrated iron oxide and calcium phosphate, and it has a synergistic effect when used in conjunction with other corrosion and scale inhibitors. At present, the environmental protection department strictly controls the discharge of phosphate, and the industrial circulating water and boiler feed water ...

AI Technical Summary

Problems solved by technology

The product yield of the continuous production process of hydroxyethylene diphosphonic acid is greater than 95%, and the product quality can reach a phosphorus content of less than 1.0%, and a phosphorus content of less than 0.5%, which overcomes the low yield and many side reactions of other preparation processes. Disadvantages of high content of phosphorous acid and phosphoric acid