Process for production of aromatic polycarboxylic acids

A continuous process for producing a polycarboxylic acid product is disclosed. The process comprises combining a methyl substituted aromatic hydrocarbon, an oxidation catalyst, and an oxygen-containing gaseous stream in a reaction zone to produce a reaction mixture. The oxygen-containing gaseous stream includes non-condensible gases. The reaction mixture in the reaction zone is subjected to a predetermined temperature and pressure for a predetermined residence time to produce an admixture of reactants and reaction products. The reaction products include a vapor phase and a product-containing liquid phase. Heat is removed from the product-containing liquid phase by withdrawing a portion of such liquid stream from the reaction zone and passing such reaction zone-removed portion to a heat-removal/separation zone.