| 摘要 |
<p>Processes are disclosed for recovery and purification of dibasic aromatic acids or esters thereof from waste polyester film, fiber, bottles, manufacturing residues, and other manufactured articles. The processes comprise: depolymerization of polyester resin in a liquid solvent under conditions of elevated temperature and pressure suitable for opening of ester bonds to form a solution of dibasic aromatic acid or ester, polyol, organic impurities, and other components of the resin; crystallization of the dibasic aromatic acid or ester from the solution by flash crystallization to form a vapor containing a major amount of the polyol and solvent, and a slurry of dibasic aromatic acid or ester crystals in mother liquor; separation of crude dibasic aromatic acid or ester from the mother liquor; crystallization of retained organic impurities from the mother liquor solution by flash crystallization to a pressure in a range downward from about one atmosphere to form a slurry of mother liquor solids; recovery of mother liquor solids from the slurry; and recycle of the recovered mother liquor solids to the depolymerization.</p><p>Crude acid is, optionally, purified by hydrogenation in an aqueous solution at elevated temperatures and pressures in the presence of hydrogen and an insoluble metal-containing catalyst, which is thereupon separated from the aqueous solution, and purified dibasic aromatic acid recovered by crystallization and mechanical separation from the aqueous solution. Purified terephthalic acid has, typically, an L*-value in a range of from about 95 to about 100, an a*-value in a range of from about -1 to about +1, and a b*-value in a range of from about 0.5 to about 2.</p> |
