Depolymerization of poly(ethylene terephthalate) in dilute aqueous ammonia solution under hydrothermal conditions

Abstract

BACKGROUND: Various methods, such as glycolysis, methanolysis, and hydrolysis with supercritical water, have been investigated for chemical recycling of poly(ethylene terephthalate) (PET), which is used in large quantities for beverage containers. However, a more effective process is needed.

Kinetics of catalytic glycolysis of PET wastes with sodium carbonate

“…Great attention is currently paid to chemical recycling, which basically involves the recovery of monomers leading to the yield of interesting value-added chemicals or intermediates from PET waste [3][4][5][6]. PET is a polyester with functional ester groups that can be cleaved by reagents, such as water, acids or bases (hydrolysis) [7][8][9], alcohols (alcoholysis) [10,11], amines (aminolysis) [12,13], ammonia (ammonolysis) [14] and glycols (glycolysis) [15,16]. Particularly, the glycolysis reaction is the molecular degradation of PET polymer by glycols, typically ethylene glycol (EG), where ester linkages are broken and replaced by hydroxyls terminals to give bis(2-hydroxyethyl terephthalate) (BHET), according to the following reaction scheme,…”

Effect of temperature management on the hydrolytic degradation of PET in a calcium oxide filled tube reactor

“…In recent years, a variety of chemical recycling processes have been developed to recover feedstocks for the chemical industry. Solvolysis processes using water, methanol and glycol can be used to gain terephthalic acid [5][6][7][8][9], dimethyl terephthalate (DMT) [10,11], bishydroxyethyl-terephthalate (BHET) [12][13][14] and glycol from bottle PET, which has a high purity. It may well prove possible to make use of ionic liquids as an alternative for the depolymerisation of PET [15].…”

Hydrolytic degradation of poly(ethylene terephthalate) in a pyrolytic two step process to obtain benzene rich oil

“…In recent years, a variety of different chemical recycling methods have been developed to recover feedstock for the chemical industry. Solvolysis processes using water, methanol, and glycol have been used to gain terephthalic acid, [4][5][6][7][8] dimethyl terephthalate (DMT), 9,10 bishydroxyethyl-terephthalate (BHET), [11][12][13] and glycol. All of these products can be employed in the production of new PET.…”