Patent ID: 8901321

Claim:
A process for recovering maleic anhydride from a gaseous reaction mixture, said process comprising the following steps: (a) feeding the gaseous reaction mixture at a temperature between 120 to 200° C. to an high efficiency absorption column, wherein the absorption column includes a feed zone, an absorption section disposed above the feed zone and a stripping section disposed below the feed zone; (b) recovering the maleic anhydride contained in the reaction gas in the absorption zone of said column, by: (i) a first gas cooling section comprising a packing section where a sensible and an absorption heat is removed through cooling of a recirculation solvent stream, withdrawn from a chimney tray located above the feed zone, cooled in an external heat exchanger by cooling water at a controlled temperature and recycled back above said packing section; (ii) a second gas cooling section above the first one, for removing from 10 to 30% of a total heat removed from the two cooling sections, through a recirculation solvent stream cooled in a heat exchanger using cooling water at controlled temperature; (iii) a main absorption section, formed from fractionation trays, where the reaction gas at a temperature below 90° C. is contacted with a stream of organic solvent stripped under vacuum, but still containing a small amount of maleic anhydride, fed under controlled conditions of flow-rate and temperature, to an intermediate tray near to the top of the absorption column, (iv) a final absorption section, formed from one or more suitable trays, where the reaction gas, at this point containing a very small amount of maleic anhydride, is further washed by a small stream of organic solvent, from 10 to 25% of the total amount of the solvent, coming from a solvent washing section, where demineralized water is used to remove accumulated impurities and polymerization tars, being such solvent stream fully without any maleic anhydride; and (c) stripping the enriched organic solvent coming from the feed zone by a stream of hot air in the bottom section, containing trays or packing, of the same absorption column.