| 摘要: | 寶特瓶 (poly(ethylene terephthalate)的廣泛使用及其不可生物降解的特性，使得寶特瓶的回收已經成當代重要的議題。根據文獻，寶特瓶被乙二醇解 (Glycolysis of PET)後，可得到單體雙（2-羥乙基）對苯二甲酸酯 (Bis(2-hydroxyethyl) terephthalate)。由於乙二醇醇解需依賴催化劑，所以先前的文獻都較注重在催化劑的選擇和反應參數優化，來達
到單體之高產率，但由於完整的乙二醇解製程也同時需要用到過濾、結晶、烘乾等單元操作，這些單元操作在製程上對產品的影響也值得被探討。因此，本研究主要為探討乙二醇解反應、過濾、結晶和烘乾，每一個步驟對於整個乙二醇醇解製程上的影響。首先，將 10 g 寶特瓶碎片、乙二醇 (30 及 60 mL)及碳酸鈉 (0.0276、0.0555 及 0.111 g) (催化劑) 加入至附有100mL聚醚醚酮杯(PEEK cup)的高壓釜反應器中，攪拌速率為550rpm，在乙二醇醇解反應中探討不同反應溫度 (165 °、185 °或 195°C)、反應時間 (1、2 或 3h)、不同重量催化劑 (0.0276、0.0555 及 0.111 g) 以及不同體積的乙二醇 (30 及 60 mL)所造成的影響，反應結束後，將高壓釜自然降溫至室溫，加入熱水並保持溫度在 65 °C 一個
小時，並過濾掉殘留的固體或是不純物並乾燥，其中探討不同體積熱水(60、120 及 240 mL)所造成的影響，之後將濾液從 65 °C 冷卻降溫至 25 °C，析出白色的雙（2-羥乙基）對苯二甲酸酯結晶，在結晶過程中，探討不同攪拌速率(0 及 600 rpm)、結晶時間(4、8及 16h)、降溫速率(5 °C/h 或 80 °C/h)以及溶液起始濃度(110.24、73.49 及 44.10 mg/mL)
所造成的影響。因為產品具有多晶型，在結晶過程中也對控制多晶型進行討論。最後將雙（2-羥乙基）對苯二甲酸酯結晶過濾並且在 40°C 的烘箱烤乾。並探討多晶型對過濾及烘乾影響。雙（2-羥乙基）對苯二甲酸酯結晶進行從篩網、光學顯微鏡(OM)、傅立葉轉換紅外線光譜儀(FT-IR)、粉末 X 射線繞射儀(PXRD)、差示掃描量熱儀(DSC)、核磁共振儀(NMR)和液相層析儀(HPLC)的檢測結果分別確認雙（2-羥乙基）對苯二甲酸酯的物理化學特性與結構。;Recycling poly(ethylene terephthalate) (PET) bottles has been discussed widely since its omnipresence and non-biodegradable characteristics. It has been reported that PET can be chemically recycled by glycolysis. The bis(2-hydroxyethyl) terephthalate monomer was the desired product of glycolysis of PET. Previous studies mainly focused on reaction parameters such as catalyst type, amount of catalyst, reaction temperature, reaction time, stirring rate and volume of ethylene glycol (EG) to achieved the high yield of product.However, there were also other processing steps after glycolysis, BHET dimer filtration, crystallization, BHET monomer filtration and drying. The development of those steps is essential because each step can affect the product quality and the process efficiency. Therefore, the aim of my research is to explore the influence of each step from glycolysis to BHET dimer filtration to crystallization to BHET monomer filtration and finally to drying on the whole glycolysis process. Firstly, 10 g of PET flakes, EG (30 and 60 mL) and Na2CO3(0.0276, 0.0555 and 0.111 g) as catalyst were added into an autoclave containing a 100 mL of PEEK cup size and heated a given temperature with a stirring rate of 550 rpm. Then, the autoclave was cooled to room temperature overnight by turning off the autoclave. In glycolysis, the effects of the reaction temperature (165 °, 185 ° and 195 °C), reaction time (1, 2 and 3h), amount of catalyst (0.0276, 0.0555 and 0.111 g) and volume of EG (30 and 60 mL) on the yield of BHET monomer would be studied. After glycolysis, hot water was added and the product medium was kept at 65 °C for 1h and then filtered to separate BHET
monomer from dimer. In filtration, the effect of the different amount of hot water added (60, 120 and 240 mL) in filtration would be investigated. The filtrate was cooled form 65 ° to 25 °C, and white BHET monomer were crystallized. In crystallization, the effect of different stirring rates of 0 and 600 rpm, crystallization time of 4, 8 and 16h, cooling rate of 80 °C/h and 5 °C/h and initial of concentration of 110.24, 73.49 and 44.10 mg/mL of filtrate on yield, purity, polymorphism and crystal size distribution of BHET monomer. Finally, BHET monomer were filtered and oven dried at 40 °C. The characterizations for all BHET monomer by sieving, optical microscope (OM), Fourier transform infrared spectroscopy(FT-IR), powder X-ray diffractometer (PXRD), differential scanning calorimeter (DSC), nuclear magnetic resonance (NMR) and high performance liquid chromatography (HPLC) to ascertain their physicochemical and structural properties. |
