Studies on the catalytic activities of ZSM-5 zeolites with different aluminum contents in the green oxidation of α-pinene to high value-added products

Abstract

α-Pinene is the terpene abundant in nature. It is present in the oils of coniferous trees, mainly pine. We demonstrate that from this renewable stock, high value-added products such as verbenone, verbenol, α-pinene oxide, can be obtained as the main products, and smaller quantities of pinanediol carvone myrtenol pinocarveol campholenic aldehyde, myrtenal, and carveol are also produced. All the products have numerous applications in medicine, cosmetics, and foods. Heterogeneous ZSM-5 zeolite catalysts with different aluminum contents – designated as (in wt% of Al) ZSM-5_1 (2.5), ZSM-5_2 (0.59), and ZSM-5_3 (0.38) – were applied in the green α-pinene oxidation with oxygen and without solvent. To date, the use of the ZSM-5 catalyst in the α-pinene oxidation process has not been described. The catalysts were characterized by UV-Vis, FTIR, EDXRF, XRD, SEM, DTA techniques, and by the nitrogen sorption method at 77 K. The effects of catalyst amount and properties, temperature and reaction time, on product selectivity and α-pinene conversion, were determined.