Crown ether induced assembly to γ-Al2O3 nanosheets with rich pentacoordinate Al3+ sites and high ethanol dehydration activity

Abstract Two-dimensional (2D) materials have attracted great attention due to their unique physical and chemical properties derived from the dimensionality effect and modulation in their band structure. Herein, an important industrial catalytic material, gamma alumina (γ-Al 2 O 3 ) with well-defined two-dimensional nanosheet structure was fabricated by a designed crown ether induced assembly approach. The obtained γ-Al 2 O 3 nanosheets with a thickness of ∼4 nm possess high surface area (351 m 2 /g) and 16% pentacoordinate Al 3+ sites which are the main catalytic active sites for ethanol dehydration to ethylene, compared to almost no pentacoordinate Al 3+ sites for the commercial γ-Al 2 O 3 nanoparticles. Furtherly, systematical investigation reveals that the crown ether plays the key role in the assembly of nanosheet structure. As a catalyst for ethanol dehydration to ethylene, the obtained alumina nanosheets with easily-accessible surface and more active sites, exhibit a superior catalytic performance to the commercial alumina with a much higher yield at large space velocity.