Silica-supported phosphotungstic acid as a novel heterogeneous catalyst for β-pinene polymerization

We report an efficient and environmentally friendly heterogeneous catalyst for β -pinene cationic polymerization based on silica supported phosphotungstic acid (HPW/SiO 2 ). The catalysts were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed desorption of ammonia (NH 3 -TPD) and FT-IR spectra. XRD and TEM analysis of HPW/SiO 2 indicate that the particles of HPW are amorphously uniformly distributed on the surface of the silica. NH 3 -TPD results indicate that the total acid amount and acidity increased with increasing the loading amount. FT-IR spectra analysis shows that the structure of Keggin does not change when HPW was supported on silica. Their catalytic performance for β -pinene polymerization was also tested. Under the optimal conditions, the yield of poly( β -pinene)s was up to 90.4 %, and the number-average molecular weight was about 1,100.