Patent ID: 6235932
Filing Date: 2001-05-22
Classification: C07C

Abstract:
A process for preparation of adipic acid from cyclohexane consisting essentially of:forming a reaction mixture in liquid phase of cyclohexane and preactivated catalyst in a gas liquid stirred reactor;bubbling pure molecular oxygen in the said liquid phase reaction mixture at a space velocity of 15-50 hr.sup.-1, at a temperature in the range of 90-110.degree. C. and a pressure in the range of 15-35 Kg/cm.sup.2 while stirring the said reaction mixture so as to ensure that the said liquid phase reaction mixture is homogenous and also that above 90% of the pure oxygen is consumed in the reactor by recirculating the gas bubbles several times in the said reactor thereby forming a reaction mixture including oxidation products, cyclohexane, water and catalyst;diluting the unreacted oxygen gas coming out of the said homogenous liquid with nitrogen such that the gas phase concentration of oxygen is less than 5%;removing the volatile products from the said resultant mixture by distillation to form a residue comprising catalyst and the oxidation products;extracting the oxidation products from the said residue using methyl ethyl ketone or acetone, filtering off and drying the separated catalyst for recycling the same;recovering the said oxidation products by evaporating the solvent and drying;repeatedly recrystallising the said oxidation products to separate pure adipic acid, using solvents selected from the group consisting of water, acetic acid, and methanol, from unrecoverable cyclohexane; andrecycling the unreacted cyclohexane.