SAITO Hidefumi Research & Development Senior Research Scientist Center, Nippon Kasei Chemical C, 企画開発本部研究所, 主任研究員
YOSHIOKA Toshiaki Faculty of Engineering, Tohoku University Research Asociate, 工学部, 助手 (30241532)
齊藤 秀史 日本化成(株), 企画開発本部研究所, 主任研究員
斉藤 秀史 日本化成(株), 企画開発本部研究所, 主任研究員
|Budget Amount *help
¥9,800,000 (Direct Cost : ¥9,800,000)
Fiscal Year 1996 : ¥3,800,000 (Direct Cost : ¥3,800,000)
Fiscal Year 1995 : ¥6,000,000 (Direct Cost : ¥6,000,000)
Recently, a disposal of waste materials has been in current focus as one of the environmental problems familiar to every people, since it is difficult to set up intermediate treatment plants as an incinerator or the land for reclamation in the world. Polyethylene terephthalate (PET) resin is used not only in many industries but also in daily life, since it is inexpensive, light, transparent, tough and easy in processing. In particular, it is used for bottles, the demand for which is increasing year by year.
In this work, used PET flakes were oxidized by oxygen in NaOH solutions. In this case, PET was converted to terephthalic acid (TPA) and ethylene glycol (EG) by the hydrolysis, and only EG was oxidized simultaneously to oxalic acid. This is the first study recycling of used PET to TPA and oxalic acid particular. The optimum conditions were investigated to obtain oxalic acid in high yield from used PET flakes.
Oxidation of post consumer PET to TPA and oxalic acid in NaOH solutions was studied to disclose the optimum conditions. PET was completely hydolyzed first to TPA and EG during heating, and oxalic acid and CO_2 were formed by oxygen introduction. Since sparingly soluble sodium terephthalate in concentrated NaOH solutions is stable to the oxidation, the yield of TPA was reached ca.100unit% under all conditions. On the other hand, EG was oxidized to oxalic acid by base-catalyzed oxygen-oxidation and the maximum yield of oxalic acid was 60.7 unit%. Also, the yields of oxalic acid for commercial transparent flakes and mixture of transparent and green-colored flakes from PET bottles reached 65.9 unit% and 71.4 unit%, respectively.