Abstract: The present invention provides a solvent extraction purification method for aromatic polycarboxylic acids that meet or exceed polymer-grade specification. The method includes dissolving a crude aromatic polycarboxylic acid in a base compound; removing impurities and excessive base compound; and removing residual base compound while making purified product. The purification method removes not only the impurities from the crude acid, but also the residual base compound from finished product that otherwise will contaminate the product. The salt in the cake is converted to product by acid-substitution, thermal decomposition, or electrolysis. The method uses base-extraction solvents to extract base compound and impurities from the salt. The residual base compound in the recovered product is then removed by leaching, stripping, thermal agitating with electromagnetic waves, or evaporation with thermal decomposition.

Abstract: The present invention provides a solvent extraction purification method for aromatic polycarboxylic acids that meet or exceed polymer-grade specification. The method includes dissolving a crude aromatic polycarboxylic acid in a base compound; removing impurities and excessive base compound; and removing residual base compound while making purified product. The purification method removes not only the impurities from the crude acid, but also the residual base compound from finished product that otherwise will contaminate the product. The salt in the cake is converted to product by acid-substitution, thermal decomposition, or electrolysis. The method uses base-extraction solvents to extract base compound and impurities from the salt. The residual base compound in the recovered product is then removed by leaching, stripping, thermal agitating with electromagnetic waves, or evaporation with thermal decomposition.

Abstract: The present invention provides a solvent extraction purification method for aromatic polycarboxylic acids or derivatives that meet or exceed polymer-grade specification. The method includes dissolving a crude aromatic polycarboxylic acid or derivative in a base compound; removing impurities and excessive base compound; and removing residual base compound while making purified product. The purification method removes not only the impurities from the crude acid or derivative, but also the residual base compound from finished product that otherwise will contaminate the product. The salt in the cake is converted to product by acid-substitution, thermal decomposition, or electrolysis. The method uses base-extraction solvents to extract base compound and impurities from the salt. The residual base compound in the recovered product is then removed by leaching, stripping, thermal agitating with electromagnetic waves, or evaporation with thermal decomposition.

Abstract: The present invention provides a process for purifying crude aromatic polycarboxylic acids having one or more condensed rings, wherein two or more carboxylic acid groups can be at any position of the aromatic ring or rings. The process uses solvents consisting of two families of organic compounds as major solvent: a monocyclic compound containing two hetero-atoms and alkylamine compound, and two families of co-solvent: water and alcohol, to separate impurities from the crude acids. The product purity from the instant invention can be achieved to a level that is significantly better than the current state of the art.