Effective catalysis of poly(ethylene terephthalate) (PET) degradation by metallic acetate ionic liquids

Zhou, Xueyuan; Lu, Xingmei; Wang, Qian; Zhu, Minli; Li, Zengxi

doi:10.1351/PAC-CON-11-06-10

Pure Appl. Chem., 2012, Vol. 84, No. 3, pp. 789-801

http://dx.doi.org/10.1351/PAC-CON-11-06-10

Published online 2012-02-08

Effective catalysis of poly(ethylene terephthalate) (PET) degradation by metallic acetate ionic liquids*

Xueyuan Zhou^1,2, Xingmei Lu¹*, Qian Wang¹, Minli Zhu² and Zengxi Li²

¹ Beijing Key Laboratory of Ionic Liquids Clean Process, Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
² College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049, China

Abstract: Poly(ethylene terephthalate) (PET) is widely used for beverage bottles, electrical and electronic instruments, household wares, and so on. As a consequence of dramatically increasing consumption, recycling of post-consumer PET products has become an important environmental opportunity for sustainable usage in society. In this paper, we investigated the use of chlorine-free metallic acetate ionic liquids (ILs) as catalysts for the degradation of PET because of their lower toxicity, corrosivity, and cost. 1,3-Diethylimidazolium triaceticzincate ([deim][Zn(OAc)₃]) behaved as the best in this group. The synthesized ILs and the major product, characterized by a variety of techniques and factors affecting glycolysis, were examined. Under optimum conditions, conversion of PET reached 98.05 %, and the selectivity of the bis(hydroxyethyl) terephthalate (BHET) monomer was 70.94 %. A probable mechanism for the glycolysis of PET catalyzed by [deim][Zn(OAc)₃] was given. In our opinion, catalysis accounted for the synergic effect of the cation and anion of the IL.

*Pure Appl. Chem. 84, 411–860 (2012). A collection of invited papers for the IUPAC project 2008-016-1-300 “Chlorine-free Synthesis for Green Chemistry”.