Effect of Support Size on the Catalytic Activity of Metal-Oxide-Doped Silica Particles in the Glycolysis of Polyethylene Terephthalate

Abstract

Zinc oxide (ZnO) and cerium oxide (CeO2) nanoparticles were deposited on the surface of preformed silica spheres with diameters ranging from 60 to 750 nm. Ultrasonic irradiation was employed to promote the deposition of the metal oxide nanoparticles on the surface of silica. Silica-supported zinc oxide or cerium oxide was used as a catalyst in the glycolysis of polyethylene terephthalate, one of the key processes in the depolymerization of polyethylene terephthalate. The effect of the support size on the catalytic activity was studied in terms of monomer yield, and the monomer concentration was analyzed via high-performance liquid chromatography (HPLC). The morphologies and surface properties of the catalysts were characterized using a scanning electron microscope, a transmission electron microscope, and a BET surface area analyzer, while the monomer was characterized via HPLC and nuclear-magnetic-resonance spectroscopy. Both the zinc oxide and cerium oxide deposited on a smaller support showed better distribution and less aggregation. The high specific surface area of the smaller support catalysts provided a large number of active sites. The highest monomer yield was obtained with a catalyst of 60-nm silica support.

Recent Developments in the Chemical Recycling of PET

“…Fig. 5 Wi et al, 2011) shows TEM images of the fabricated 60 nm (a) and 150 nm (b) silica nanoparticle used as supports and the supports with the deposited metal oxide catalysts. The metal oxide catalysts were deposited on the silica nanoparticle supports via a simple ultrasound assisted precipitation method.…”

Recovery of Terephthalic Acid by employing magnetic nanoparticles as a solid support

“…All the mentioned catalysts such as alkalies, metal acetate, zeolites, ionic liquids and etc, in the PET glycolysis reactions required long reaction times and contributed low BHET and TPA yields. In order to resolve these drawbacks and improve reaction conditions Imran et al [14,15] used thermally stable and highly selective silica nanoparticle-supported metal (Mn, Zn, Ce) oxides as the catalysts for PET depolymerization. After that, Park et al [16] outstretch graphene oxide and manganese oxide as the catalysts for PET glycolysis.…”

Practical Design of Green Catalysts for PET Recycling and Energy Conversion

“…The catalytic performance of the synthesized γ-Fe 2 O 3 nanoparticles was compared to previously studied silica nanoparticle-supported metal oxide catalysts [10,40]. Under the same reaction conditions and catalyst/PET weight ratio, γ-Fe 2 O 3 delivered comparable performance ( Figure 12).…”

“…Among the recoverable catalysts studied are various ionic liquids, which were shown to provide molar yields up to 80% [36][37][38][39]. Aside from yield, there are several issues that should be considered in using ionic liquids as industrial glycolysis catalysts such as cost, stability, and robustness with respect to process variables such as moisture content, to which ionic liquids are very sensitive [10,11,40]. Urea was also reported to be a reusable glycolysis catalyst at mild temperatures [41].…”