Process to recycle exhaust gases from n-butane conversion into maleic anhydride

Process for the production of maleic anhydride by catalytic oxidation of n-butane in the vapor phase, comprising the steps of:

• compressing air, oxygen-enriched air or oxygen to a pressure of 1.21 to 3.04 bar;
• mixing said air, oxygen-enriched air or oxygen with recovered exhaust gas to form a recycle gaseous stream;
• compressing said recycle gaseous stream to a pressure of 2.03 to 6.08 bar to form a compressed recycle gaseous stream;
• mixing said compressed recycle gaseous stream with a butane feed to form a reaction mixture at a pressure of 2.03 to 6.08 bar;
• the percentage of exhaust gas in said recycle gaseous stream being regulated such that said reaction mixture has an oxygen content of from 10% to 18% by volume, and the amount of butane being regulated such that the total butane concentration in said reaction mixture ranges from 1.6% to 3.0% by volume;
• feeding said reaction mixture to an oxidation reactor where said butane is catalytically reacted to produce maleic anhydride and other reaction gases comprising nitrogen, oxygen, non-converted butane, organic by-products and water steam;
• cooling said maleic anhydride and other reaction gases;
• feeding said maleic anhydride and other reaction gases to an absorber containing an absorption medium selected from the group consisting of water and an organic solvent to recover said maleic anhydride and produce an exhaust gas fraction, said absorber operating at an outlet pressure of 1.21 to 3.04 bar;
• water-scrubbing said exhaust gas fraction to remove all organic compounds except non-converted butane to produce said recycle gaseous stream and a remaining exhaust gas fraction;
• conveying said remaining exhaust gas fraction to an incinerator where butane and organic products in the remaining exhaust gas fraction are burnt to produce water and carbon dioxide.