Simultaneous Recovery of Benzene-Rich Oil and Metals by Steam Pyrolysis of Metal-Poly(ethylene terephthalate) Composite Waste

Abstract

The possibility of simultaneous recovery of benzene and metals from the hydrolysis of poly(ethylene terephthalate) (PET)-based materials such as X-ray films, magnetic tape, and prepaid cards under a steam atmosphere at a temperature of 450 °C was evaluated. The hydrolysis resulted in metal-containing carbonaceous residue and volatile terephthalic acid (TPA). The effects of metals and additives on the recovery process were also investigated. All metals were quantitatively recovered, and silver, maghemite (γ-Fe2O3), and anatase (TiO2) were recovered without any changes in their crystal structures or compositions. In a second step, TPA was decarboxylized in the presence of calcium oxide (CaO) at 700 °C, producing benzene with an average yield of 34% and purity of 76%. Maghemite (γ-Fe2O3) incorporated in magnetic tape and prepaid cards could decarboxylate TPA. Aluminum present in the prepaid cards produced hydrogen by the reaction with steam. However, the presence of metals had no adverse influence on the recovery of benzene-rich oil in the presence of CaO. Therefore, this method can be applied to PET-based materials containing inorganic substances, which cannot be recycled effectively otherwise.

Catalytic de-halogenation of alkyl halides by copper surfaces

“…The organic matter in halogenated wastes is embedded with high energy content. The recyclability of halogenated polymers into important industrial feedstocks (olefins, in particular) heavily relies on near complete removal of their bromine/chlorine content [11,12].…”

Toward Making Poly(ethylene terephthalate) Degradable in Aqueous Environment

“…The second one (≈40%) from 378 to 541°C can be ascribed to the thermal decomposition of PET; this is evident from the comparison with the TG curve of PET pellets as well as TG data in the literature. [21] The last weight loss above 540°C is expected to result from the decomposition of Ca(OH) 2 and CaCO 3 impurities, which are produced by side reactions between CaO, H 2 O and CO 2 in the storage of PET/CaO. [22] The TG and DTG curves of the hydrolysis product obtained from the 75/25 PET/CaO composite show two weight-loss stages.…”

Latest Trends in Pyrolysis Gas Chromatography for Analytical and Applied Pyrolysis of Plastics

“…Pyrolysis is a promising feedstock recycling technique for the conversion of waste plastics into monomers, fuels, and valuable chemicals through the cleavage of multiple chemical bonds. [57][58] This is distinctly advantageous in treating heterogeneous plastic wastes consisting of several types of plastics combined with inorganics such as metals and fillers, [59][60][61] the optimum temperature for the pyrolysis of plastics and the optimum temperature for reaction with solids are different in most of the cases. To overcome this limitation and to evaluate the pyrolysis of plastics and the catalyst performance under the best conditions, a tandem micro-reactor (TR), in which the first micro-reactor is used for pyrolysis or volatilization of the substances and the second micro-reactor is used for catalytic reactions, was developed.…”