聚對苯二甲酸乙二酯的一鍋甲醇解聚：以異丙醇輔助二氧化碳氫化

Abstract

由於工業的快速發展，塑膠廢棄物的污染和二氧化碳的過度排放都成為迫切需要被解決的環境問題，為了維持永續以及碳中和的環境，塑膠以及二氧化碳回收再利用的技術便成為學界和業界共同努力的目標。本研究透過一鍋反應法(one-pot reaction)將聚對苯二甲酸乙二酯(poly(ethylene terephthalate), PET)進行化學回收，此方法利用Cu/ZnO催化劑上透過二氧化碳氫化產生的甲醇，將PET降解為對甲苯二甲酸二甲酯(dimethyl terephthalate, DMT)和乙二醇，並添加催化溶劑以增加甲醇產生速率及產量，並探討溶劑結構對此反應的影響。反應測試結果顯示，以異丙醇作為催化溶劑可有效提升PET一鍋甲醇解中甲醇的產量及PET的轉化率，同時維持DMT的高選擇率。透過不同反應條件的活性測試，我們發現異丙醇的高選擇率可歸因於其本身不易與PET和DMT進行轉酯化反應的特性，在最佳化的條件下(220°C, 6 h)，可得到63.1%的PET轉化率以及57.2%的DMT產率，大幅提升在未添加異丙醇系統的PET轉化率(31.9%)和DMT產率(25.8%)，顯示了以異丙醇催化二氧化碳氫化反應是一種具有潛力的一鍋PET甲醇解方法，同時將廢棄PET和二氧化碳進行再利用。

Plastic pollution and CO2 emissions have emerged as critical issues requiring immediate attention to achieve a sustainable, carbon-neutral society. Addressing these challenges demands the development of novel processes to recycle and repurpose waste plastics and CO2 resulting from human activities. This study focuses on the chemical recycling of poly(ethylene terephthalate) (PET) through a one-pot process, wherein PET is transformed into dimethyl terephthalate (DMT) and ethylene glycol by methanol (MeOH) produced in-situ via CO2 hydrogenation over the Cu/ZnO catalyst. To enhance MeOH and DMT yields, this study investigates the impact of alcohol addition during the one-pot PET methanolysis. Specifically, isopropanol (i-PrOH) is employed as a catalytic solvent within the CO2-H2-PET system. The results demonstrate the effectiveness of i-PrOH as a catalyst solvent, significantly boosting PET degradation while maintaining high selectivity for DMT. This selectivity is attributed to the limitation of i-PrOH to PET alcoholysis and DMT transesterification abilities. At 220°C for 6 hours, the CO2-H2-PET-i-PrOH system achieves a PET conversion of 63.1% and a DMT monomer yield of 57.2%, surpassing the results obtained from the CO2-H2-PET system, which had a PET conversion of 31.9% and a DMT yield of 25.8%. The findings underscore the potential of i-PrOH-assisted CO2 hydrogenation as a promising approach for one-pot PET methanolysis, enabling the efficient valorization of waste PET and CO2. Ultimately, this research offers valuable insights for the development of sustainable and efficient processes.