METHOD OF PREPARING ADIPIC ACID Russian patent published in 1996 - IPC

FIELD: chemical engineering. SUBSTANCE: adipic acid is prepared by oxidizing cyclohexanol or its mixture with cyclohexanon with nitric acid in presence of copper- vanadium catalyst at elevated temperature including recycling through oxidation reactor of 90-93% of reaction mixture got free from nitrogen oxides using blowing and evacuation followed by washing leaving nitrous gas with salt-free water at pressure 0.31- 0.33 MPa and 30-40 C and final isolation of product by known techniques. Novelty consists in that leaving nitrous gases are additionally washed with cyclohexanol at 30-50 C and excess pressure, washed gases are divided into two flows, one of which (57-61%) is directed for blowing off leaving nitrous gases from recycling reaction mixture, and remaining gas flow is directed to washing with cyclohexanon cooled to temperature from -15 to -20 C and constituting 20-40% of common weight of cyclohexanol- cyclohexanon mixture. Cyclohexanon absorbate obtained is mixed with cyclohexanol absorbate and directed into oxidation reactor. EFFECT: increased selectivity of oxidation. 2 cl, 2 dwg, 1 tbl