A highly porous MgAl2O4 spinel-supported Mn3O4 as a reusable catalyst for glycolysis of postconsumer PET waste

• Published in: Journal of industrial and engineering chemistry (Seoul, Korea) Korea), 2022-11, Vol.115, p.251-262
• Main Authors: Zhang, Haoxiang, Choi, Jong In, Choi, Jung-Weon, Jeong, Se-Min, Lee, Pyung-Soo, Hong, Do-Young
• Format: Article
• Language: English
• Subjects: BHET; Heterogeneous catalyst; PET; Porous metal oxide spinel; Regenerable catalyst
• ISSN: 1226-086X
• DOI: 10.1016/j.jiec.2022.08.006

[Display omitted] •Porous MgAl2O4 spinel-supported Mn3O4 catalyst was successfully synthesized from MgAl-LDH via thermal and chemical treatment, followed by Mn oxide loading.•High surface area and medium acid-base properties of the catalyst enhanced the PET conversion and BHET yield.•The catalyst was highly recyclable without significant deactivation and regenerable with complete recovery of the initial activity. A porous MgAl2O4 spinel-supported Mn3O4 catalyst, which is an efficient and robust catalyst for polyethylene terephthalate (PET) glycolysis, was synthesized from MgAl-layered double hydroxide (LDH) as a template via thermal and chemical treatment, followed by Mn oxide loading. A mesoporous structure in the MgAl2O4 spinel provided a high surface area (278 m2/g) and defects in which Mn3O4 was highly dispersed and strongly stabilized by the substitution of Al3+ and incorporation of Mn cation into the defects. The strong interaction of Mn oxide and the porous MgAl2O4 spinel support led to a dramatic increase of moderate acidic and basic properties, and to high resistance for Mn leaching during glycolysis. Using the Mn3O4/p-spMgAl800 catalyst, a yield of bis(2-hydroxyethyl) terephthalate > 95% was achieved within 3 h at 190 ℃. Despite eleven recycling times with regeneration, the catalytic activity remained without significant deactivation and was completely recovered after thermal regeneration at 500 ℃.