| 摘要 |
Adipic acid is made by reacting cyclohexane in the liquid phase with molecular oxygen at a temperature of from 100 DEG C. to 140 DEG C. to oxidize from 5 to 15% of the cyclohexane present and to produce a liquid product comprising cyclohexanol, cyclohexanone and unreacted cyclohexane, separating cyclohexane from the liquid product and reacting the residual liquid with molecular oxygen in the presence of a solvent to produce adipic acid. The first oxidation may be effected in the presence of a metal oxidation catalyst, preferably a cobalt salt soluble in cyclohexane, such as cobalt acetate or naphthenate. Cyclohexane may be present as an initiator. The oxidation can be carried out in a series of reaction zones, preferably four, each equipped with cooling means and agitators and constructed for operation in a pressure range of 100 to 500 p.s.i.g. Cyclohexane is fed in at a space velocity of from 2 to 125 volumes per liquid volume per hour. Air, oxygen or oxygen-enriched air may be employed. The cyclohexane may be removed from the product of the first stage by distillation or other suitable means. The residual oil containing cyclohexanone and cyclohexanol in a weight ratio of 0.9 to 1 or more is a solvent such as acetic, propionic, butyric, iso-butyric or valeric acid and oxidized at a temperature in the range of 70 DEG to 105 DEG C. at pressures between 85 and 400 p.s.i.g. The liquid product is discharged into a crystallization zone to obtain adipic acid crystals which are purified by recrystallization. Specification 941,662 is referred to.
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