Series of 1-allyl-3-methylimidazolium halometallate ionic liquids (ILs) were synthesized and used to degrade poly(ethylene terephthalate) (PET) as catalysts in the solvent of ethylene glycol. One important feature of these new IL catalysts is that most of them, especially [amim][CoCl 3 ] and [amim][ZnCl 3 ], exhibit higher catalytic activity under mild reaction condition, compared to the traditional catalysts [e.g., Zn(Ac) 2 ], the conventional IL catalysts (e.g., [bmim]Cl), Fe-containing magnetic IL catalysts (e.g., [bmim][FeCl 4 ]), and metallic acetate IL catalysts (e.g., [Deim][Zn(OAc) 3 ]). For example, using [amim][ZnCl 3 ] as catalyst, the conversion of PET and the selectivity of bis(hydroxyethyl) terephthalate (BHET) reach up to 100% and 80.1%, respectively, under atmospheric pressure at 175 C for only 1.25 h. Another important feature is that BHET can be easily separated from the catalyst and has a high purity. Finally, based on the experimental phenomena, in -situ infrared spectra, and experimental results, the possible mechanism of degradation with synthesized IL is proposed.
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.
Glycolysis of poly(ethylene terephthalate) with ethylene
glycol
was carried out with the catalysts of sulfated cobalt oxide (SO4
2–/Co3O4) and zinc-modified
sulfated cobalt oxide (SO4
2–/Co–Zn–O).
The catalysts prepared at different calcination temperatures have
been characterized by various techniques. These techniques include
X-ray diffraction, Raman spectrum, gas adsorption analysis, NH3-temperature programmed desorption, and IR spectroscopy of
pyridine adsorption. The performances of these catalysts on the depolymerization
of PET under mild conditions were studied, and relationships between
the catalysts’ textural properties, the surface acidity, and
the catalytic activity have been investigated. The experimental results
showed that the catalytic activity on glycolysis of PET was significantly
improved by the catalysts of binary sulfur oxides of SO4
2–/Co–Zn–O. The conversion of PET
obtained on SO4
2–/Co–Zn–O-300
°C was 96%, and the selectivity of BHET was 75%, after 3 h at
180 °C under atmospheric pressure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.