In 1937, the American DuPont Company first realized the industrial production of adipic acid by oxidizing cyclohexanol (produced by hydrogenation of phenol) with nitric acid. In the 1960s, the industry gradually switched to the cyclohexane oxidation method, that is, the intermediate product cyclohexanone and cyclohexanol mixture (ie ketol oil, also known as KA oil) was first prepared from cyclohexane. Then carry out nitric acid or air oxidation of KA oil.
(1) One-step oxidation of cyclohexane
Using cyclohexane as raw material, acetic acid as solvent, cobalt and bromide as catalyst, at 2MP. And 90 ℃ of reaction 10 ~ 13h. Yield 75%.
(2) Stepwise oxidation of cyclohexane
The preparation of KA oil can be directly oxidized with air at 1.0～2.5MPa and 145～180℃, and the yield can reach 70%～75%. Metaboric acid can also be used as a catalyst for air oxidation at 1.0～2.0MPa and 165℃, the yield can reach 90%, and the ratio of alcohol to a ketone is 10:1; The boric acid is recovered from the layer, and dehydrated into metaboric acid for recycling; the organic layer is saponified with caustic soda to saponify the organic ester, and the acid is removed, and the alkanol-ketone mixture is obtained after recovering cyclohexane by distillation.
Oxidation of KA Oil The KA oil is oxidized with excess 50%-60% nitric acid in a two-stage series reactor at 60-80°C and 0.1-0.4MPa. The catalyst is copper-vanadium series (copper 0.1%-0.5%, vanadium 0.1%-0.2%), and the yield is 92%-96% of the theoretical value. After the reactant is distilled out of nitric acid, high-purity adipic acid can be obtained through two crystallization purifications.
DOUWIN is a professional adipic acid factory in China, and we will show you some tips for packing adipic acid.
The boiling point of adipic acid is 330.5℃ and the adipic acid melting point is 152℃. Adipic acid should be handled in a closed manner. Operators must undergo special training and strictly abide by operating procedures. Factory operators must wear self-priming filter dust masks, anti-gas permeable work clothes, labor insurance shoes and rubber gloves, and filter gas masks if necessary. Smoking is strictly prohibited in the workplace. Use explosion-proof ventilation systems and equipment. Avoid generating dust. When handling, it should be lightly loaded and unloaded to prevent damage to packaging and containers. And be aware that emptied containers may have harmful residues.
Store in a cool, ventilated, rain-proof warehouse. Keep away from fire and heat sources. It should be stored separately from oxidants, reducing agents and alkalis, and should not be mixed. Equipped with the corresponding variety and quantity of fire fighting equipment and leakage emergency treatment equipment. Storage areas should be provided with suitable materials to contain spills.
The packaging should be complete and the loading should be secure at the time of shipment. During transportation, make sure that the container does not leak, collapse, fall or be damaged. It is strictly forbidden to mix and transport with oxidants, reducing agents, alkalis, edible chemicals, etc. During transportation, adipic acid should be protected from exposure to sunlight, rain, and high temperature. The vehicle should be thoroughly cleaned after transportation.
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