Preparation of Hydrotalcite/SBA-15 Composite Catalyst and its Application in the Synthesis of ε-Caprolactone

Polycaprolactone (PCL) is a highly regarded biodegradable and environmentally friendly material that is extensively researched and applied in the field of biomedicine due to its exceptional biodegradability, biocompatibility, and other advantageous properties. The monomer ε-Caprolactone (ε-CL) plays a critical role in the synthesis of PCL, making it a key focus of study. This paper describes the preparation of hydrotalcite HT-Zn and SBA-15 through simple synthetic methods, and the subsequent creation of a hydrotalcite/SBA-15 composite catalyst, named HT-Zn/SBA-15, through a post-generation approach combining hydrotalcite and SBA-15. Scanning electron microscopy (SEM), wide-angle X-ray diffraction (XRD), and infrared spectroscopy (FT-IR) were employed to analyze the structures of the synthesized materials. The catalytic effects in Baeyer–Villiger oxidation were then investigated to examine the impact of various catalysts, solvents, and reaction conditions. The results indicated that utilizing HT-Zn/SBA-15 as the catalyst, acetonitrile as the solvent, and H₂O₂ as the oxidant, led to a conversion rate of cyclohexanone exceeding 80% and a selectivity of ε-CL surpassing 90% under the ideal reaction conditions. Additionally, the catalyst demonstrated excellent reusability, being able to be reused up to six times.