Dodecanedioic Acid CAS 693-23-2

Add 400kg of ordinary dodecanedioic acid and 3kg of coconut shell activated carbon to 1000L90wt.% edible alcohol, make slurry in a 2m3 glass-lined decolorization kettle, heat up to 65°C, press filter with a 30m2 box-type underflow plate, and filter the filtrate through a precision filter Go to the crystallization tank, cool down to crystallize, cool down to 25°C, centrifuge, put the centrifuge into a clean glass-lined low-temperature washing tank, add 200L95wt.%, 15°C alcohol, stir evenly, centrifuge twice, put the centrifuge into the double cone Dry in a vacuum dryer, control the material temperature at 45°C±1°C, vacuum degree -0.085～-0.10MPa, dry until the moisture content is lower than 0.1wt.%, and finish drying to obtain 328kg of refined acid. Gas chromatographic determination of product single acid content 99.17wt.%, neutralization titration determination of total acid content 99.5wt.%, ester content was not detected, mother liquor and drying recovery alcohol distillation process with 30% liquid caustic soda to control the pH The value is 12, 1180L of alcohol is obtained by distillation, and the alcohol content is 92wt.%. Alcohol rectification of high boilers to produce mixed acids yielded 63.5kg of mixed acids with a total acid content of 98.5wt.%, a dodecanedioic acid content (gas chromatography) of 90.26wt.%, and a water content of 0.35wt.%.

① Adsorption and decolorization
In the dissolution reactor, put 1000 parts by weight of deionized water, add 180 parts by weight of crude dodecanedioic acid in dry weight under stirring, add 110 parts by weight of sodium hydroxide aqueous solution with a mass concentration of 30.3%, and heat up to 100 °C , the pH value is controlled between 6.0, after the material is completely dissolved, add 3 parts by weight of coconut shell-type activated carbon, and keep warm for 20 minutes for decolorization;

②Oxidative decolorization
Filter the material treated in step ① while it is hot, rinse the filter cake with hot water at 90°C, put the filtrate and flushing liquid into the oxidation decolorization reaction kettle, raise the temperature to 98°C, and control it at 5~ Within 10 minutes, add hydrogen peroxide with a mass content of 30%, oxidize and decolorize under stirring, and heat-preserve and oxidize for 2 hours at a temperature of 98-100°C to prepare acidified crystallization;

③Acid crystallization
a. Configuration of dilute sulfuric acid
In the dilute sulfuric acid preparation kettle, add 105 parts by weight of deionized water, under cooling and stirring, slowly add 40 parts by weight of 98.5% concentrated sulfuric acid dropwise to prepare dilute sulfuric acid with a mass percentage concentration of 27.2%, and cool to room temperature. ready to crystallize;

b. Acidification, crystallization
Slowly add the 27.2% dilute sulfuric acid prepared in step a into the dodecanedioic acid aqueous solution treated in step ② under stirring, control the acid precipitation temperature at 98°C, and crystallize for 1.5 hours. With the addition of dilute sulfuric acid, Fish scale crystals are constantly precipitated in the solution, and the pH value at the end of the acidification is controlled to be 3.0. After adding the acid, heat and stir for 15 minutes, cool down and crystallize, stop cooling when the temperature drops to 25°C, vacuum filter, and use 500 parts by weight of deionized The filter cake is washed with water, and the washing liquid is recovered and recycled as the solvent of the next batch;

④ Drying
The filter cake after vacuum filtration in step 3.b is dried at a temperature of 100-105° C.;

178 parts by weight of scale-like high-purity dodecanedioic acid crystals are obtained; the product yield is 98.9%.