Technique for preparing sodium dimethyl 5-sulfoisophthalate

Abstract

The invention relates to a technique for preparing sodium dimethyl 5-sulfoisophthalate. A sulfonation kettle (a), an esterification kettle (B), an extraction kettle (C), a back washing kettle (D), a decolorization / impurity suction kettle (E), a filter (F), an intermediate crystallizing kettle (G), a centrifugal dehydrator (H), a thermal dissolution kettle (J), a fine filter (K), a terminal crystallizing kettle (L), a secondary dehydrator (M) and a drying machine (N) are used as technological equipment; and m-phthalic acid (1) and fuming sulfuric acid (2) are used as main raw materials. In the technical process of all steps, methanol (4), deionized water (7), a sodium carbonate solution (10), activated carbon (12), oxydol (13), compressed air (14), deionized water (7) and activated carbon (12) are sequentially added into related equipment according to the technical requirements to prepare the sodium dimethyl 5-sulfoisophthalate finished product (27) at specific temperature and time under technological conditions of the technical process of all the steps. The finished product has the advantages of high purity, good quality, low cost and high yield, relieves the environmental pollution, and has favorable economic and social benefits.

Description

technical field [0001] The invention relates to the production process of chemical products, in particular to the technology of extracting useful chemical substances from the production wastewater of three monomers. Background technique [0002] Dimethyl isophthalate-5-sodium sulfonate is commonly known as a three-monomer, which is mainly used to synthesize the third monomer of cationic dyeable polyester, so that the polyester fiber has good affinity for cationic dyes, and can be used for normal dyeing. Pressure dyeing, bright color, complete color spectrum, high color fastness, good antistatic, hygroscopicity, anti-pilling and air permeability, making clothes comfortable to wear. The production method is to sulfonate isophthalic acid first, and then go through methanol esterification, soda ash or caustic soda neutralization, purification and other processes to make products. Since sulfur trioxide is used for sulfonation in the production process, the reaction is violent an...

AI Technical Summary

Problems solved by technology

Since sulfur trioxide is used for sulfonation in the production process, the reaction is violent and many impurities are generated, so low-concentration fuming sulfuric acid must be used for sulfonation. The excess sulfuric acid in the sulfonation process will generate a large amount of sodium sulfate, which will be discharged during the neutralization process. The waste water contains a large amount of organic matter and sodium sulfate, which will pollute the environment, and it is difficult to recycle and treat

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