FREMANGSMAATE TIL UTVINNING AV RENE DIKARBOKSYLSYRER, DISSES ANHYDRIDER OG/ELLER DISSES ESTERE

摘要

Process for isolating pure dicarboxylic acids, anhydrides and/or esters (27) from crude products (12) containing these compounds by subjecting these with gases or gas mixtures (1) which are in the supercritical state at temperatures above the critical temperature and pressures below the critical pressure of the gas or gas mixture used to an extraction (11) using the following gases or gaseous compounds not only individually but also in the form of mixtures with one another as extractants: CO2, N2O, fluoro/chlorocarbons, NH3, SO2, CH3Cl, C2H4, C2H6 and CH3OH. The process is particularly suitable for purifying the products of the air oxidation of hydrocarbons for the production of fumaric acid, maleic acid, phthalic anhydride, adipic acid, dimethyl adipate, terephthalic acid and dimethyl terephthalate.