Synthesis of Poly(butylene succinate) Catalyzed by Tetrabutyl Titanate and Supported by Activated Carbon

Polybutylene succinate (PBS) is a biodegradable aliphatic polyester with excellent thermal stability, mechanical properties, and processability. The synthesis of PBS typically employs titanium-based catalysts like tetrabutyl titanate (TBT) to accelerate the reaction. However, TBT acts as a homogeneous catalyst and is non-recyclable. This study aims to minimize the cost of recovering liquid TBT catalyst during PBS synthesis by using TBT-loaded activated carbon for direct esterification and optimizing the process conditions. The catalyst was analyzed using inductively coupled plasma emission spectroscopy, automated specific surface area and pore size analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy. The product was evaluated through infrared spectroscopy, nuclear magnetic resonance hydrogen spectra, and gel permeation chromatography. The optimal process parameters were determined to be an esterification temperature of 170 °C, a polycondensation temperature of 235 °C, an acid-to-alcohol molar ratio of 1:1.2, a catalyst amount of 0.06 g, and a dehydration time of 3 h. Under these conditions, the weight-average molecular weight of PBS reached 47,655, reducing the catalyst usage from 0.5% to 0.3%, resulting in a 24.7% increase in catalytic efficiency compared to TBT, significantly lowering costs. After five cycles of reuse, the weight-average molecular weight of the product remained above 35,000. This study demonstrates that TBT-loaded activated carbon exhibits superior catalytic performance, offering a cost-effective and efficient method for industrial PBS production with broad application potential.