有色废弃PET材料化学回收新工艺

Chemical degradation and recycling of coloured polyethylene terephthalate waste

为了解决有色废弃PET材料回收难的问题,促进资源循环利用,研究了有色PET以超临界甲醇技术进行解聚,并脱色提纯得到对苯二甲酸二甲酯的工艺流程。探讨了有色PET在超临界甲醇中的降解规律,并对脱色方案进行了筛选。探索了不同级别的PET材料解聚条件的差异。结果表明:纤维级材料在265℃,11MPa下,超临界甲醇解聚30min后,用溶解-热过滤-沉析的方法脱色提纯,对苯二甲酸二甲酯的产率可达到85%,纯度达到99.9%以上,白度达到87.5%;瓶片级材料呈现的解聚规律与纤维级变化趋势相同,但达到相同的解聚率,明显需要更长的反应时间。

In order to reduce the pollution produced by polyethylene terephthalate （PET） wastes and promote resource recycling, the degradation of PET in supercritical methanol yielding dimethyl terephthalate （DMT） was studied, and the decolorization methods for the product were investigated. It was found that fiber-grade PET can be depolymerized though supercritical methanol in about 30min at 265~C and llMPa with DMT yield of nearly 85%, and the monomer has the purity to fiber-grade PET. While, it needs longer time for bottle-grade PET to reach the same depolymerization.