| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a polyester, capable of enhancing the recovery rate of germanium dioxide to reuse the germanium dioxide at a lowered recovery cost by recovering and purifying the germanium compound distilled out on the polycondensation reaction and subsequently reusing the recovered germanium compound as a polycondensation catalyst. SOLUTION: This method for producing a polyester comprises carrying out a polycondensation reaction in the presence of germanium dioxide as a catalyst, subjecting the reaction distillate by-produced with the advance of the reaction to a distillation condensation treatment, purifying the germanium compound contained in the condensed solution, and subsequently reusing the purified germanium compound as the catalyst of the polycondensation reaction. Therein, the germanium dioxide obtained by separating a part of oligomers contained in the reaction distillate and subsequently subjecting the separated part to a concentration treatment and a purifying recovery process is reused as the catalyst.
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