Production method and system for co-production of acetyl chloride by 1-hydroxyethylidene-1,1-diphosphonicacid

Abstract

The invention provides a production method for co-production of acetyl chloride by 1-hydroxyethylidene-1,1-diphosphonicacid. The method comprises the following steps: starting a reaction still for stirring, pumping a certain amount of acetic acid or acetic acid aqueous solution in, and meanwhile dripping a certain amount of phosphorus trichloride into the reaction still for mixing; after mixing, leading into a heat exchanger for preheating; preheating a mixed material, leading into a synthesis reactor for an esterification reaction, enabling generated acetyl chloride to enter into a rectifying tower to be separated to obtain high-purity acetyl chloride or back drop into the synthesis reactor, enabling hydrochloric acid and uncondensed acetyl chloride to enter a multi-stage exhaust absorption apparatus; enabling generated acetic ester to enter a hydrolysis kettle for hydrolyzation, promoting acetic ester to evaporate out by negative pressure operation to be reused, replenishing deionized water to promote the hydrolyzation to obtain HEDP, and reusing excess heat through a steam recycling machine on the heat exchanger. The production method has the following beneficial effects: the production efficiency is promoted; the operative difficulty and labor intensity are reduced; the technical parameter requirements on the synthesis reactor can be lowered; the reaction efficiency can be greatly improved; product overstocking caused by acetyl chloride encountering poor sales is avoided; the production cost is saved; the exhaust emission is reduced.

Description

technical field [0001] The invention belongs to the technical field of chemical production, and in particular relates to a production method and system for co-producing acetyl chloride from hydroxyethylene diphosphate. Background technique [0002] Hydroxyethylene diphosphate, referred to as HEDP, structural formula: (H 2 PO 3 ) 2 C(OH)CH 3 . The pure product is a white crystal, easily soluble in water and methanol, with a melting point of 198-199°C. HEDP can form stable complexes with various metal ions such as iron, copper, zinc, etc., can dissolve oxides on the metal surface, and is still stable at high pH values. It is usually used as a complexing agent, water quality stabilizer, and masking agent , extractant, etc. HEDP can form six-ring chelates with metal ions in water, especially calcium ions, so it has good scale inhibition effect and obvious solubility limit effect. When used in combination with other water treatment agents, it shows ideal synergy Effect, wi...

AI Technical Summary

Problems solved by technology

The disadvantage of the prior art is that after the single-pot reaction, it needs to be cleaned and re-feeding, which greatly reduces the reaction efficiency, and multiple types of reactions occur in the single-pot, which requires high technical requirements for the reactor. Moreover, it is difficult to Realize the motorized adjustment of the relative output of HEDP and acetyl chloride. In addition, the aqueous acetic acid produced by hydrolysis in the later stage cannot be directly used, which increases the difficulty of recovering acetic acid.

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