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Multiple Hydrogen Bonds Promote the Nonmetallic Degradation Process of Polyethylene Terephthalate with an Amino Acid Ionic Liquid Catalyst

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journal contribution
posted on 05.03.2021, 15:07 by Haoyu Yao, Xingmei Lu, Lin Ji, Xin Tan, Suojiang Zhang
The formation of hydrogen bonds in the polyethylene terephthalate degradation process is beneficial for the break of ester bonds and accelerates the reaction. Therefore, we designed a series of amino acid ionic liquid catalysts, which have several donor and receptor groups and can form multiple hydrogen bonds with the reactants to enhance the nonmetallic degradation process. By comparing with the traditional catalysts, the designed catalysts avoid the introduction of metal elements and have a similar catalytic efficiency to the traditional metal catalysts. Under the optimal conditions with [Bmim]­Pro, the conversion reached 100.0% and the yield of bis­(2-hydroxyethyl terephthalate) reached 75.3%. The catalyst has good recycling performance under the reaction condition. Through two-dimensional overhauser enhancement spectroscopy, it was found that there are multiple interactions between [Bmim]­Pro and the reactants. Multiple hydrogen bonds between reactants and [Bmim]­Pro were proved by density functional theory (DFT) calculations. Finally, the reaction kinetics were studied, which are consistent with the shrinking-core model.