Verfahren zur Wiedergewinnung von Katalysator und gleichzeitigen Entfernung von Nebenprodukten

摘要

1,165,597. Synthesis of 1,12 dodecanedioic acid. E. I. DU PONT DE NEMOURS & CO. 6 Nov., 1967 [12 Dec., 1966], No. 50426/67. Heading C2C. A process is described for the simultaneous removal of by-products and catalyst recovery from the recycle liquid stream remaining after the nitric acid oxidation of cyclododecanol/ cyclododecanone in the presence of a coppervanadium catalyst and subsequent removal of the 1,12 dodecanedioic acid product by crystallization. The recycle liquid comprises HNO 3 , water, dibasic acids containing from 4 to 12 carbon atoms, monobasic acids and copper-vanadium catalyst, and is maintained at 40-110‹ C. The concentrations of the components of the recycle liquid are adjusted to a level where the weights of the various components, on a total liquid basis, are inorganic salt 0À1-10%, dibasic acids 5-80%, and HNO 3 less than 25% with the proviso that the weight of HNO 3 is less than 55% of the total HNO 3 and water present. Under the above conditions two liquid phases, oil and water form and are separated. The aqueous phase can be recycled for use in the nitric acid oxidation reaction. Adjustment of the concentrations of the various components of the recycle liquid may be by evaporation, addition of water, addition of inorganic salt e.g. the nitrates and sulphates of Cu+ +, Na+, Mg+, Ca++ or addition of externally recycled oil. Examples illustrate both batchwise and continuous operation of the process.