Purification of aromatic diacids
AssigneeMossi & Ghisolfi Overseas S.A.
InventorThomas Fairchild Brownscombe
Life of this patent
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Abstract
A method is provided to produce dicarboxylic or tricarboxylic aromatic acid from salts of such acids, the method including the steps of providing an aqueous solution of a salt of a dicarboxylic or tricarboxylic aromatic acid, the aqueous solution having a pH of about 7 or greater; contacting the aqueous solution with sufficient carbon dioxide to lower the pH of the aqueous solution resulting in precipitation of at least a portion of the dicarboxylic or tricarboxylic aromatic acid; separating precipitated dicarboxylic or tricarboxylic aromatic acid from the solution; and recovering carbon dioxide from the solution.
Claims18
A method to recover dicarboxylic or tricarboxylic aromatic acid from salts of such acids, the method comprising the steps of:
- providing an aqueous solution of a salt of a dicarboxylic or tricarboxylic aromatic acid, the aqueous solution having a pH of about 7 or greater;
- contacting the aqueous solution with sufficient carbon dioxide to lower the pH of the aqueous solution resulting in precipitation of at least a portion of the dicarboxylic or tricarboxylic aromatic acid;
- separating precipitated dicarboxylic or tricarboxylic aromatic acid from the solution;
- recovering carbon dioxide from the solution;
- and
- contacting the separated precipitated dicarboxylic or tricarboxylic aromatic acid with oxalic acid under conditions effective to disproportionate any monosalt of the dicarboxylic or tricarboxylic aromatic acid present to a mixture of disalt and dicarboxylic or tricarboxylic aromatic acid.
A method to recover dicarboxylic or tricarboxylic aromatic acid from salts of such acids, the method comprising the steps of:
- providing an aqueous solution of a salt of a dicarboxylic aromatic acid selected from the group consisting of phthalic acid, isophthalic acid or of a tricarboxylic aromatic acid, or mixtures thereof, the aqueous solution having a pH of about 7 or greater;
- contacting the aqueous solution with sufficient carbon dioxide to lower the pH of the aqueous solution resulting in precipitation of at least a portion of the dicarboxylic or tricarboxylic aromatic acid;
- separating precipitated dicarboxylic or tricarboxylic aromatic acid from the solution;
- and
- recovering carbon dioxide from the solution.
Dependencies are inferred from the claim text.