UiO-66(Zr/Ti) for catalytic PET polycondensation.

• UiO-66 (Zr/Ti) was used to catalyze the synthesis of PET for the first time. • Through chemical process optimization, PET with a lower b value was successfully synthesized in a 5 L reactor, which provided inspiration for MOF materials in industrial catalysis. • The DFT calculations revealed that the reaction path of UiO-66(Zr/Ti) was more suitable for the coordination of the carboxy oxygen atom mechanism, and the reaction activation energy of 22.37 kacl/mol was close to that of the Sb-based catalyst. PET (poly(ethylene terephthalate)) is one of the most important type of thermoplastic polyesters and widely used in various fields. Titanium-based catalysts are environmentally friendly and have higher catalytic activity than antimony-based catalysts when used in industry. However, titanium-based catalysts are prone to hydrolysis and result in discolored products. UiO-66 (Zr/Ti) with different Ti4+ contents were successfully synthesized via one-step method. The material was characterized by XRD, SEM, FT-IR, XPS, BET and TG techniques. The results demonstrates that Ti4+ was integrated into the UiO-66 framework. NH 3 - in situ DRIFTS, pyridine-IR, and NH 3 -TPD were used to explore the acidic properties of the samples, which proved that stable Lewis acidic sites are present in the samples even at 300 °C. The catalytic performance of UiO-66 (Zr/Ti) containing different Ti4+ was explored under different conditions. At the same time, the scale-up experiment was carried out in a 5 L reactor, and the PET chips obtained had a lower b value. The catalytic reaction mechanism of UiO-66(Zr/Ti) was demonstrated by DFT calculations and the catalytic performance was close to Sb-based catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]