SYSTEM FOR PRODUCING POLYCARBOXYLIC ACID, USING COOLED MOTHER SOLUTION FROM OXIDATIVE COMBUSTION AS CLEANING SYSTEM CHARGE Russian patent published in 2012 - IPC C07C51/21 C07C51/43 C07C59/42 C07C63/26 C08G63/183 

FIELD: chemistry.

SUBSTANCE: method of producing a polycarboxylic acid composition involves: (a) oxidation of a multiphase reaction medium containing an oxidisable starting aromatic compound, a solvent and water, in a primary oxidation zone to obtain a starting suspension containing crude terephthalic acid; (b) oxidative combustion of at least a portion of said starting suspension in a combustion zone to obtain a combustion product suspension having one or more of the following characteristics: (i) contains less than 9000 ppm isophthalic acid; (ii) contains less than 15000 ppm benzoic acid, (iii) contains less than 64 ppm 4,4'-dicarboxybiphenyl, (iv) contains less than 70 ppm 2,6-dicarboxyfluorenone, (v) contains less than 12 ppm 2,7-dicarboxyfluorenone, (vi) contains less than 12 ppm 9-fluorenone-2-carboxylic acid, (vii) contains less than 4 ppm 4,4'-dicarboxystilbene, (viii) contains less than 6 ppm 4,4'-dicarboxyanthraquinone; (c) cooling at least a portion of said combustion product suspension in a cooling zone to obtain a cooled suspension containing cooled liquid and solid phases; and (d) using the solvent cleaning system to remove at least one aromatic impurity containing benzoic acid, para-toluic acid, 4-carboxy-benzaldehyde and/or trimellitic acid, present in the solvent cleaning charge, fed into said solvent cleaning system, where said cooled liquid phase of said cooled suspension forms at least 20 wt % of said solvent cleaning charge.

EFFECT: invention discloses systems for more efficient and cheap production of polycarboxylic acid.

112 cl, 30 dwg, 4 tbl