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The Development of Recycling Process of Waste PET to TPA and Oxalic Acid by Alkaline Hydrolysis-oxidation

废旧PET碱性水解氧化回收TPA和草酸工艺开发

基本信息

批准号：
07558082
负责人：
OKUWAKI Akitsugu
金额：
$ 6.27万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07558082/
关键词：
Waste PET Alkaline Hydrolysis Oxygen-oxidation Recycling Terephthalic Acid Oxalic Acid

项目摘要

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.

近年来，由于垃圾处理厂作为焚烧炉或复垦用地的建设难度较大，废物处理已成为人们普遍关注的环境问题之一。聚对苯二甲酸乙二醇酯(PET)树脂因其价格低廉、轻质透明、韧性好、易于加工等优点，不仅在许多行业中得到应用，而且在日常生活中也得到了广泛的应用。尤其是用于需求量逐年增加的瓶子。在本工作中，使用过的PET片材在NaOH溶液中被氧气氧化。在这种情况下，PET通过水解转化为对苯二甲酸(TPA)和乙二醇(EG)，只有EG同时被氧化为草酸。这是首次研究回收废旧涤纶制得TPA和草酸的特殊方法。研究了从废旧聚酯切片中高产率地获得草酸的最佳工艺条件，并研究了后消费聚酯在氢氧化钠溶液中氧化生成TPA和草酸的最佳工艺条件。在加热过程中，PET首先完全水解生成TPA和EG，然后通过氧气引入生成草酸和CO2。由于稀溶对苯二甲酸钠在浓NaOH溶液中对氧化稳定，TPA的产率在所有条件下都可达到100单位%左右。乙二醇碱催化氧氧化制草酸，草酸的最高产率可达60.7单位%。商品透明鳞片和透明绿色混合鳞片的草酸产率分别达到65.9单位%和71.4单位%。