Fabrication of a 3D Hierarchical Flower-Like MgO Microsphere and Its Application as Heterogeneous Catalyst

A 3D hierarchical flower-like MgO microsphere was successfully obtained by pyrolysis of the flower-like Mg5(CO3)(4)(OH)(2)center dot 4H(2)O microsphere precursor which was itself synthesised by means of a facile and environmentally friendly hydrothermal route from MgCl2 center dot 6H(2)O. The possible formation process of the microsphere precursor was systematically investigated and considered to result from the following steps: (i) forming the 1D pillar-like MgCO3; (ii) cracking to a 2D flake structure; (iii) assembling to the 3D flower-like Mg-5(CO3)(4)(OH)(2)center dot 4H(2)O microsphere. The obtained close-packed 3D flower-like MgO microsphere has cubic symmetry and high crystallinity assembled by nanoflake particles with a mean diameter of 10 mu m. Moreover, the heterogeneous catalysis of the Claisen-Schmidt condensation reaction between benzaldehyde and acetophenone to synthesise chalcones was also studied. The 3D flower-like MgO microsphere exhibited better catalytic performance than that of commercial MgO and this was attributed to the especially 3D hierarchical flower-like structure and the large surface area.