Morphology dependent effect of γ-Al2O3 for ethanol dehydration: nanorods and nanosheets.

Boehmite (γ-AlOOH) nanorods and nanoplates were hydrothermally fabricated with the aid of tetrapropylammonium bromide (TPABr) by modifying the pH values of solutions. Under acidic conditions, the adsorption of anions such as Br− or NO3− on (001) and (100) surfaces may promote the heterogeneous nucleation of boehmite, leading to rod-like boehmite. While under basic solutions, the adsorption of TPA+ cation on the (010) surface inhibits the growth of boehmite along the [010] direction and generates nanosheets. The as-synthesized γ-AlOOH precursors were calcined at 873 K and transformed into γ-Al2O3 nanorods and nanosheets. The obtained γ-Al2O3 samples presented a clear morphology-depended effect for ethanol dehydration; nanorods gave the improved selectivity of C2H4 due to the exposure of {100} facets. [ABSTRACT FROM AUTHOR]