La(OH)3 and La2O2CO3 nanorod catalysts for Claisen-Schmidt condensation

La(OH)3 nanorods of 15 nm diameter and up to 700 nm long were synthesized using different pH values of the solution used in the hydrothermal synthesis. A more alkaline solution favored the formation of tiny La(OH)3 nuclei, which grew along the c-axis due to their anisotropic nature and led to the formation of rod-shaped crystals. Calcination of the La(OH)3 nanorods at 773 K gave La2O2CO3 nanorods. Their basic properties were correlated with their size. As the aspect ratio increased from 2 to 20, the basic sites increased from 0.08 to 0.24 mmol/g, which was due to a higher exposure of (110) planes. In the catalysis of the condensation reaction of benzaldehyde with acetophenone, the reaction rate was correlated with the number of La3+−O2− pairs on the exposed (110) facets of the La2O2CO3 nanorods.

Graphical AbstractThe basicity of La2O2CO3 nanorods increased with increasing aspect ratio, and their catalytic activity for Claisen-Schmidt condensation was associated with the La3+−O2− sites on the (110) facets.Figure optionsDownload as PowerPoint slide