Patent ID: 6706932
Filing Date: 2004-03-16
Classification: C07C

Abstract:
A method for producing a diol mixture comprising 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol, which comprises:(A) providing a dicarboxylic acid mixture comprising succinic acid, glutaric acid and adipic acid and having a nitric acid content of 0.2% by weight or less, based on the total weight of said succinic, glutaric and adipic acids, said dicarboxylic acid mixture being prepared by denitrating an aqueous by-product solution obtained in an adipic acid production process comprising subjecting at least one C6 cyclic aliphatic compound to oxidation with nitric acid in an aqueous medium in the presence of an oxidation catalyst to thereby obtain an aqueous reaction mixture comprising succinic acid, glutaric acid and adipic acid, depositing crystals of the adipic acid, and isolating the deposited crystals from said reaction mixture to obtain the aqueous by-product solution; and (B) subjecting said dicarboxylic acid mixture to hydrogenation in the presence of water, hydrogen gas and a hydrogenation catalyst containing an active metal species comprising ruthenium and tin, to thereby obtain a hydrogenation reaction mixture comprising a diol mixture comprising 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol.