Highly Efficient Synthesis and Property Characterization of PETG Using Titanium-Based Bimetallic Catalysts

A series of titanium-based bimetallic catalysts (Ti–M, where M = Mg, Mn, Ca, Co, Al) were synthesized via the sol–gel method for the preparation of polyethylene terephthalate-1,4-cyclohexanedimethanol ester (PETG). Their catalytic performance was compared to that of conventional catalysts, specifically tetrabutyl titanate (TBT) and germanium dioxide (GeO 2 ). Results showed that Ti–M catalysts exhibited excellent catalytic activity at a 6 ppm loading. Among them, the Ti–Co catalyst demonstrated a rate constant of 7.53 × 10 –3 min –1 during esterification, surpassing both TBT and GeO 2 . The Ti–Mg catalyst achieved the highest reaction rate in the polycondensation stage, producing PETG with a number-average molecular weight of 2.87 × 10 4 g/mol and a relatively narrow polymer dispersity index ( Đ = 2.08). Analyses revealed that PETG synthesized with the Ti–Mg catalyst had a higher thermal decomposition activation energy, indicative of improved thermal stability. These titanium-based bimetallic catalysts demonstrate high efficiency and superior performance in PETG synthesis, making them promising alternatives to traditional catalysts.