期刊
GREEN CHEMISTRY
卷 24, 期 21, 页码 8447-8459出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/d2gc02860c
关键词
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资金
- Ministry of Human Capacities [UNKP-22-2-I-BME-146, UNKP-21-3-I-BME-311, UNKP-20-5-BME-322]
- Hungarian Academy of Science
- National Research, Development, and Innovation Office [FK138037, K128473]
- Gedeon Richter Talentum Foundation (Gedeon Richter Plc.)
- Gedeon Richter's Centenary Foundation
Chemical depolymerisation is a sustainable plastic recycling method that can achieve a circular economy by recovering pure monomers. In this study, commercially available organocatalyst-modified silica gels and functionalized silica gel were tested for the glycolysis of PET. The reaction was optimized and the recyclability of the catalysts was evaluated. The results showed that the modified silica gels had higher catalytic activities and achieved a high yield of monomers, making them a promising solution for PET waste management.
Chemical depolymerisation, or solvolysis, can be a sustainable plastic recycling method, as a circular economy can be achieved by recovering the pure monomers. Polyethylene terephthalate (PET) is a ubiquitous plastic material with short-life application and slow biodegradation, so its waste management needs to be continuously improved. In this study, we tested three commercially available organocatalyst-modified silica gels in the glycolysis of PET and developed another, functionalized with triazabicyclodecene (TBD), which was also tested. Organocatalysts are efficient in PET glycolysis, but their recyclability needs to be improved for industrial application. The applied heterogeneous modified silica gels can be recovered easily by filtration. Si-TEA catalyst was chosen for reaction optimisation because it has the highest thermal stability and good catalytic activity. The PET glycolysis process was optimised by fractional factorial experimental design and response surface methodology. Under optimal reaction conditions (PET (384 mg, 2 mmol), ethylene glycol (1.41 mL, 25.2 mmol), Si-TEA (15.5 mol%), 190 degrees C, 1.7 h), 88.5% non-isolated bis(2-hydroxyethyl) terephthalate (BHET) monomer yield was obtained. Si-TEA and Si-TBD catalysts were recycled in five reaction cycles, and with both catalysts, high cumulative BHET yields (89 and 88%, respectively) were achieved. Additionally, environmental energy impacts were calculated for the two catalysts and were compared favourably with other organocatalysts in the literature. A process scale-up was also implemented. Finally, it has been verified that modified silica gels have much higher catalytic activities than native silica gel, as solvolytic reactions using the former catalysts took a significantly shorter time.
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