Patent ID: 8546611

Claim:
A method for preparing succinic acid, comprising: producing a modified palladium-containing catalyst by using an acid and liquid-phase hydrogenation of unsaturated acid compounds on the modified catalyst at a temperature of between 40 and 120 degrees C. and a pressure of 10-25 atm; separating the catalyst from the succinic acid; wherein the modification of the catalyst is performed on a substrate having the palladium-containing catalyst delivered thereon, the delivery being performed in an oxygen-free atmosphere; the delivery being performed in an aqueous medium of succinic, maleic or fumaric acids and/or their mixtures at a Pd 2+ /acid ratio of 1:1-1:100; hydrogenating the liquid-phase unsaturated acid compounds selected from maleic, fumaric acids or their anhydrides or their mixtures; and crystallizing the succinic acid from an aqueous solution containing 0.001-0.01 wt. % succinic acid seed.