TRIMELLITIC ACID ANHYDRIDE PRODUCT RECOVERY BY STEAM STRIPPING CRUDE ANHYDRIDE OF TOTAL SOLIDS FROM PSEUDOCUMENE OXIDATION EFFLUENT AND CONTINUOUS FRACTIONATION OF STRIPPED PRODUCT

摘要

Fluid effluent from pseudocumene oxidation with molecular oxygen in the presence of acetic acid as reaction medium under liquid phase conditions or concentrate thereof is subject to simultaneous stripping of reaction medium, thermal conversion of its trimellitic acid content to crude trimellitic anhydride and steam stripping at atmospheric pressure followed by continuous fractionation of the crude anhydride to recover product anhydride of improved color and color stability. Such anhydride recovery avoids inefficiency of trimellitic acid recovery from fluid oxidation effluent by crystallization, long residence of crude anhydride at high temperature in batchwise distillation with its attendant double anhydride formation and loss of desired anhydride product.