Hierarchical Beta Zeolites As Catalysts in α‑Pinene Oxide Isomerization

Abstract

Hierarchical beta zeolites obtained in the concentrated reaction mixtures (H2O/Si = 2.5) and micromesoporous materials synthesized using a dual-template approach from a zeolite beta precursor were rigorously characterized and tested in a sustainable and environmentally friendly process of α-pinene oxide isomerization. The highest yield of trans-carveol (42%) with chemopreventive activity of mammary carcinogenesis was achieved over low crystalline micromesoporous materials characterized by well-developed mesoporosity, an increased fraction of weak-to-medium Brønsted acid sites and low Brønsted and Lewis acid sites (BAS/LAS) ratio. In turn, highly crystalline hierarchical beta zeolites with a lower mesopore volume and the mesopore surface area, stronger Brønsted acidity, and a higher BAS/LAS ratio favored the formation of campholenic aldehyde (31% yield). The mechanism of the desired product and byproducts formation was discussed and its feasibility was confirmed by kinetic modeling.