Patent ID: 6504051
Filing Date: 2003-01-07
Classification: C07C

Abstract:
Process for the continuous production of an aromatic carboxylic acid in a pressurized oxidation reactor by liquid-phase, exothermic oxidation of an alkyl aromatic hydrocarbon with an oxygen-containing gas in the presence of an oxidation catalyst and aqueous, C2-C6 aliphatic, monocarboxylic acid solvent which comprises the steps of:(1) continuously feeding to a reactor alkyl aromatic hydrocarbon, aqueous, monocarboxylic acid solvent having oxidation catalyst dissolved therein, and an oxygen containing gas; (2) continuously removing from the lower portion of the reactor product-containing liquid comprising aromatic polycarboxylic acid and the aqueous, monocarboxylic acid solvent having the oxidation catalyst dissolved therein; (3) continuously removing from the upper portion of the reactor and feeding directly into the lower portion of a water removal column reactor off-gas comprising oxygen-depleted process gas and vaporized aqueous, mono-carboxylic acid solvent; (4) continuously removing from the lower portion of the water removal column a bottoms liquid containing partially de-watered monocarboxylic acid solvent and returning to the reactor at least a portion of the bottoms liquid to the upper section of the reactor; (5) continuously removing from the water removal column overhead a vapor stream comprising oxygen-depleted process offgas, water and minor amounts of monocarboxylic acid solvent and organic by-products produced in the oxidation reactor; (6) feeding a portion of the vapor stream of step (5) to a condenser to obtain (a) a vapor comprising oxygen-depleted process gas and (b) a liquid; (7) feeding the liquid of step (6)(b) to the fractionating zone of the water removal column; and (8) feeding (i) the remaining portion of the vapor stream of step (5) and (ii) the vapor of step (6)(a), to a pollution control device wherein the monocarboxylic acid and organic by-products present in vapor streams (i) and (ii) are destroyed removed to obtain an aqueous vapor stream free or substantially free of organic compounds.