High-pressure catalytic dehydration of ethanol to ethylene over microwave-synthesized nanocrystalline zeolite β

Zeolites are widely utilized as catalysts for the dehydration of ethanol to ethylene, but many challenge remains including efficient preparation of nanosized zeolites and comprehensive understanding of reaction mechanism under various operating conditions. Herein, this study proposes a rapid microwave synthesis method with l-lysine as a surface modifier to synthesize nanocrystalline zeolite β (β-MW-Nano) catalysts and investigates their performance for high-pressure catalytic dehydration of ethanol to ethylene. X-Ray Diffraction data demonstrates that β-MW-Nano shows high crystallinity. Textural results reveal that, compared with conventionally synthesized zeolite β (β-MW) and commercial zeolite, β-MW-Nano possesses a highest specific surface area (767 m²/g), hierarchical pore structure with significant mesopore volume (0.274 cm³/g), and optimized acidity distribution. The synergistic effect of the nanocrystalline nature and hierarchical pore structure along with a balanced acid site distribution in β-MW-Nano facilitates the enhanced mass transfer and accessibility to active sites, leading to its superior catalytic activity and ethylene selectivity across all conditions (220–340 °C, atmospheric to 6.5 MPa). Detailed study on the pressure effect indicates that ethanol dehydration and conversion rate rise as increasing pressure for all samples, as elevated pressure could lower activation energy barriers, with β-MW-Nano showing the most significant decrease. Spent zeolites characterization for stability evaluation indicates that β-MW-Nano maintains higher crystallinity and resistance to coke formation. This research could provide new insights into designing efficient and stable catalysts for ethanol conversion, contributing to the advancement of sustainable chemical production processes.