Chemical recycle of polyester waste using novel zwitterionic catalysts

Waste poly (ethylene terephthalate) (PET) from drink bottles wasdepolymerized using novel zwitterionic imidazolium-2-carboxylate salts ascatalysts (or catalyst-precursors) in the presence of ethylene glycol viaglycolysis to give bis(hydroxyethyl)terephthalate (BHET). The influence ofreaction temperature, glycolysis time, ethylene glycol:PET ratios, and theamount of the zwitterionic imidazolium-2-carboxylate catalysts used on theconversion of PET, isolated yield of BHET, and the selectivity of BHET in theglycolysis of PET were investigated.<br/><br/> The results demonstrate that 1,3-dimethylimidazolium-2-carboxylate can bean effective basic catalyst for PET glycolysis, with PET depolymerization of upto 100% observed. BHET was isolated from the reaction mixture with yields ofup to 61.0% under the optimum reaction conditions using 0.15 g catalyst to 1.0g PET in the presence of 10.0 g ethylene glycol (0.15:1:10 mass ratio) at 185oCin 1 h. This is the first time that 1,3-dialkyl-imidazolium-2-carboxylates havebeen reported to be catalysts for glycolysis of PET and, compared to 1,3-dialkylimidazolium acetate ionic liquids, were more effective as catalyst in theglycolysis. The purified monomer was characterized by the nuclear magneticresonance (NMR), mass spectrometry, and high performance liquidchromatography (HPLC). <br/><br/><br/>

Name dc:type.qualificationname

Master of Philosophy

Level dc:type.qualificationlevel

Masters Thesis

Grantor dc:publisher.institution

Queen's University Belfast

Year dc:date.issued

2019

Author dc:creator

• Wang, Lei

Advisors dc:contributor.advisor

• Holbrey, John
• Swadzba-Kwasny, Malgorzata

• Poly (ethylene terephthalate) (PET)
• bis (hydroxyethyl) terephthalate (BHET)
• glycolysis
• carbene
• zwitterionic catalyst
• imidazolium2-carboxylate (NHC-CO2)

Language dc:language

eng

Identifier

oai:pure.qub.ac.uk/portal:studenttheses/a8daade3-74cb-4799-9c25-08e5ca77cd3f

OAI identifier oai:identifier

oai:pure.qub.ac.uk/portal:studenttheses/a8daade3-74cb-4799-9c25-08e5ca77cd3f