| 20110021789 | PROCESS FOR SEPARATING OFF FUMARIC ACID AND OTHER MINOR COMPONENTS DURING THE PRODUCTION OF MALEIC ANHYDRIDE - A process for decreasing fumaric acid deposits in the preparation of maleic anhydride by heterogeneously catalyzed oxidation of a hydrocarbon with molecular oxygen, in which the maleic anhydride is absorbed from the crude product mixture in an absorbent in an absorption column and desorbed again in a desorption column, the entirety or a portion of the absorbent depleted in maleic anhydride, for controlled precipitation of fumaric acid, being cooled and/or concentrated by evaporating a portion of the absorbent to such an extent that the difference between the concentration of fumaric acid in the recycle stream at the outlet of the desorption column under the conditions existing there and the equilibrium concentration of fumaric acid according to the solubility curve after the cooling and/or evaporation of a portion of the absorbent is greater than or equal to 250 ppm by weight, and the fumaric acid precipitated as a solid is removed completely or partly from the absorbent recycling system and the fumaric acid-depleted absorbent is recycled completely or partly to the absorption column. | 01-27-2011 |
