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Novel catalysts for recycling PET bottles into monomers have been developed by depositing zinc onto the surface of SBA-15, mitigating ZnO catalyst agglomeration in glycolysis separation processes to enhance reaction yields. Various zinc compounds (Zn(OAc)2, ZnCl2, and ZnSO4) were employed as substrates for catalyst design on the porous, high-surface-area material SBA-15 via impregnation. The presence of distinct Zn species on SBA-15 was confirmed through XRD and EDS analyses. The acidity of the catalyst, a crucial factor in the PET glycolysis process, was assessed using different Zn-containing precursors. NH3-TPD measurement has revealed the highest acidity in ZnCl2, followed by Zn(OAc)2 and ZnSO4, respectively. Glycolysis reactions with a PET:EG ratio of 1:5 and a 1% catalyst at 200°C for 2 hours revealed the catalytic efficacy of zincdeposited compounds in the sequence ZnCl2 > Zn(OAc)2 > ZnSO4. Surprisingly, the ZnCl2 catalyst produced the highest yield of bis-2-hydroxyethyl terephthalate (BHET) at 75% and displayed exceptional recycling capability over three cycles, contributing significantly to resource recovery objectives aligned with the Sustainable Development Goals (SDGs). [ABSTRACT FROM AUTHOR]

The promising influences of K + and Ca 2+ ions in the development of effective MnO 2 for the selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid (FDCA) were studied for the catalytic performance under a high-pressure reaction of aqueous O 2 (0.5 MPa) in a basic system. Various oxidation states of manganese in MnO 2 were able to accelerate the oxidation of 5-formyl-2-furancarboxylic acid to FDCA in the rate-determining step. The results were in good agreement that Ca 2+ played a key role in the highest FDCA yield up to 85% due to the associated cations on the local coordination to enhance the high surface area and the electronic effect on the manganese ion. Both K-MnO 2 and Ca-MnO 2 catalysts showed excellent catalytic activities without a significant change in the efficiency in the reusability experiments., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)