Ionic liquid-assisted synthesis of hierarchically olive-like Al2O3 and CeO2/Al2O3 with enhanced catalytic activity for Orange II degradation

Abstract

A simple hydrothermal method is utilized to fabricate hierarchically olive-like γ-Al2O3 using ionic liquid [Bmim]BF4 as the structure directing agent. The olive-like γ-Al2O3 presents uniform morphology with the average diameter of 500 nm and rich mesopores. As template, ionic liquid [Bmim]BF4 plays a crucial role in the controllable morphology of the product. [Bmim]BF4 is absorbed on the AlOOH nanoparticles surface via the H-bond interaction and induces crystalline oriented growth. Then the forming AlOOH nanosheets self-assemble into olive-like hierarchical structure through π–π stack interaction. Given that the structure advantage of the olive-like γ-Al2O3 and the limited study concerning cerium-based catalysts in Fenton-like reaction, nano-CeO2/γ-Al2O3 supported catalyst is prepared and used in Fenton-like degradation for the first time. The result suggests that the olive-like γ-Al2O3 support not only reduces the surface energy with more uniform CeO2 (ca. 4–5 nm) dispersion but also improve the concentration of Ce3+ active sites. The CeO2/γ-Al2O3 catalyst displays superior catalytic activity for the degradation of Orange II (AO7) compared with pure CeO2 nanoparticles.