Refining and purifying method of long carbon chain dicarboxylic acid

Abstract

The invention provides a refining and purifying method of long carbon chain dicarboxylic acid. The refining and purifying method is characterized in that the raw material moisture content of a long chain binary acid coarse product is controlled to be smaller than or equal to 1.0 wt%; the content of solvent acetic acid is larger than or equal to 95.0 wt%; the crystallization process adopts three-section gradient cooling, and induction seed crystal is added after second-section cooling to induce crystallization; crystalized filter cake is firstly sprayed by acetic acid, is next washed by water and is then subjected to centrifugal filtering; then the filter cake is washed by the water at environment temperature; an acetic acid solvent generated in the refining process is totally recycled through an azeotropic distillation method; a cleaning solution and a mother solution which are generated in the refining process are totally recycled. The refining and purifying method, high in product yield, low in refining cost and high in purity, of long carbon chain dicarboxylic acid is provided. The total acid content of long carbon chain dicarboxylic acid after being refined and purified reaches99.90%, the single acid content reaches 99.45%, the total nitrogen content reaches 6ppm, the ferric ion content reaches 0.5 ppm, the ash content is smaller than or equal to 10 ppm, and the moisture content is smaller than or equal to 0.16%. The purifying comprehensive yield reaches 98.64%. All quality technical indexes meet a user's requirements.

Description

technical field [0001] The invention is a refining and purifying method of long carbon chain dicarboxylic acid. It belongs to the purification treatment of acyclic dicarboxylic acids with more than 10 carbon atoms. Background technique [0002] Long-chain dicarboxylic acid (along-chain dicarboxylic acid)—a straight-chain dicarboxylic acid with more than 10 carbon atoms in the carbon chain, is an important class of fine chemical products. Main raw materials for synthesizing polyamide resins, polyester resins, hot melt adhesives, spices, weather-resistant plasticizers, lubricating oil additives, coatings, liquid crystals, etc. [0003] The main industrial applications include artificial synthesis of muscone; coil adhesives used for a long time at 100°C; hot-melt adhesives for clothing setting; not only can manufacture high-temperature resistant lubricants, but also can manufacture effective at -45°C low temperature Lubricating lubricant; high-performance coatings made of lon...

AI Technical Summary

Problems solved by technology

The removal of impurities increases the difficulty

Simultaneously, also reduced the purification yield of long carbon chain dibasic acid

[0014] 2. Cooling natural crystallization method, the crystallization mother liquor remaining in the decolorized filter cake has not been replaced, that is, washing with high temperature water, when a large amount of water contacts the crystallization mother liquor remaining in the filter cake, due to the influence of water on the solubility of acetic acid , so that the dissolved impurities in the mother liquor are precipitated instantly, and the residues in the filter cake are difficult to remove in the subsequent process

[0015] 3. Washing with high temperature water only speeds up the washing speed, and cannot wash away more impurities than washing at normal temperature. The purification effect is minimal, and it consumes heat energy, which increases the amount of wastewater discharged.

[0017] Due to the above deficiencies in the prior art, the total acid content and monoacid content of the refined long-chain dibasic acid products are not high enough to meet the stringent requirements of the long-chain nylon or bio-based polyamide fiber industry for the purity of long-chain dibasic acid products. requirements

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