Production of phthalic anhydride from o-xylene includes removing toluene from xylene recycle stream to increase selectivity

摘要

Production of phthalic anhydride from o-xylene by 2-stage oxidation with recycle of unreacted xylene from the first stage comprises removing toluene from the xylene recycle stream by distillation. Production of phthalic anhydride comprises: (1) partially oxidizing o-xylene in the liquid phase with oxygen or a mixture of oxygen and an inert gas in the presence of a catalyst; (2) distilling the partially oxidized mixture to separate a fraction comprising unreacted xylene; (3) distilling the xylene fraction to remove toluene; (4) recycling the xylene fraction to step (a); and (5) oxidizing the xylene-depleted partially oxidized mixture in the gas phase to produce phthalic anhydride.