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

Boehmite (gamma-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 gamma-AlOOH precursors were calcined at 873 K and transformed into gamma-Al2O3 nanorods and nanosheets. The obtained gamma-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.

Automated summary

Boehmite (gamma-AlOOH) nanorods and nanoplates were synthesized hydrothermally using tetrapropylammonium bromide (TPABr) to modify the pH values of solutions. The adsorption of different ions on specific surfaces resulted in the formation of either rod-like boehmite under acidic conditions or nanosheets under basic conditions. Calcination of the gamma-AlOOH precursors at 873 K led to the formation of gamma-Al2O3 nanorods and nanosheets with morphological effects on ethanol dehydration.