Open AccessDepolymerization of Poly(ethylene terephthalate) Wastes through Glycolysis using Lewis Acidic Bentonite Catalysts
Author(s) -
Gopal Jeya,
M. Anbarasu,
Ravikumar Dhanalakshmi,
Viswanathan Vinitha,
Vajiravelu Sivamurugan
Publication year - 2019
Publication title -
asian journal of chemistry/asian journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.145
H-Index - 34
eISSN - 0975-427X
pISSN - 0970-7077
DOI - 10.14233/ajchem.2020.22387
Subject(s) - depolymerization , catalysis , chemistry , bentonite , yield (engineering) , ethylene glycol , transesterification , ethylene , lewis acids and bases , metal , metal ions in aqueous solution , adsorption , nuclear chemistry , inorganic chemistry , organic chemistry , polymer chemistry , chemical engineering , materials science , metallurgy , engineering
In the present investigation, the authors explored the depolymerization of waste poly(ethylene terephthalate) (PET) beverage bottles using glycolysis (transesterification) catalyzed by Al3+, Fe3+ and Zn2+ impregnated bentonite catalysts. Heterogeneous catalysts such as clay, zeolite, alumina etc. preferred over homogeneous catalysts, thus we focused on the development of solid acid catalysts based on economically viable clay catalysts. The desired Lewis acidic nature was introduced by wet impregnation method at variable metal ion to clay ratio such as 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 wt. %.The effect of metal-ion loading on the surface area, pore volume and crystalline nature of the bentonite has been evaluated by nitrogen adsorption and desorption studies and XRD. The PET wastes collected from post-consumer beverage bottles were depolymerized using ethylene glycol as a glycolyting agent afforded bis(2-hydroxy ethyl)terephthalate (BHET) in 85-90 % yield under optimized conditions. The yield of BHET was observed to be increasing with increase in Lewis acidic metal ions loading from 0.5 to 4.0 wt. % as well as increase in catalysts to PET ratio. Among the catalysts, Al3+ and Zn2+-bentonite catalysts showed higher yield of BHET up to 90 % at 4 and 5 wt. % loading of metal-ion.