Study on the chemical recycling of PET to monomers by depolymerization = 해중합에 의하여 PET를 단량체로 회수하는 화학적 재생법에 관한 연구

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The current proliferation of polyethylene terephthalate (PET) as fibres, soft drink bottles and films poses serious environmental and economic concerns to the world. For the treatment of waste PET, its recycling is a promising option for the conservation of resources and environment. Various polymer recycling methods using chemical, mechanical, and thermal processes are available, but only chemical recycling conforms to the principle of sustainable development because it enables the formation of monomers. Among chemical recycling processes employing hydrolysis, methanolysis, glycolysis, and others, glycolysis is the simplest, oldest, and least capital intensive and was selected for further investigation in this set of studies. PET was depolymerized to its monomer, bis(2-hydroxyethyl) terephthalate (BHET), using excess ethylene glycol (EG) in its sub- and supercritical state. High monomer yield ($\gt 90 mol%$) was obtained at short reaction times with supercritical glycolysis because of liquid-like high diffusivity, and gas-like high solubility of EG in supercritical state. To investigate the effect of catalyst on the depolymerization, PET was depolymerized to BHET using EG in the presence of a catalyst (pure metal oxide, mixed oxide) at low temperature and pressure. The same high level ($\gt$ 90 mol %) of monomer yield was obtained as in the case of sub- and supercritical glycolysis with less severe reaction conditions. Metal oxides as glycolysis catalysts could provide a better alternate to conventional catalysts (acetates of zinc, lead, and manganese) in view of high monomer yield, high mechanical strength, high melting points, flexibility of usage in fixed and fluidized beds, possibility of regeneration, long shelf life, and extremely cost effective. The catalysts were characterized by SEM, TEM, XRD, and BET surface area while the monomer BHET was characterized by HPLC, $^1H$ NMR, $^{13}C$ NMR, DSC, and TGA. To further decrease the reaction temper...
Advisors
Kim, Do-Hyunresearcher김도현researcher
Description
한국과학기술원 : 생명화학공학과,
Publisher
한국과학기술원
Issue Date
2010
Identifier
418799/325007  / 020064508
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2010.2, [ x, 119 p. ]

Keywords

Recycling; Glycolysis; Depolymerization; PET; Monomer; 단량체; 재생; 글리콜리시스; 해중합; PET

URI
http://hdl.handle.net/10203/29263
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=418799&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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