Preparation of MgO Nanosheets with Polar (111) Surfaces by Ligand Exchange and Esterification - Synthesis, Structure, and Application as Catalyst Support

Metastable magnesium hydroxymethoxide [Mg(OH)(OCH3)] powder with nanosheet morphology was derived from a direct bottom-up synthesis using magnesium acetate tetrahydrate as precursor under solvothermal conditions, with benzyl alcohol as structure-directing agent. The synthesis is driven by esterification of magnesium acetate to the corresponding methyl acetate, namely, ligand exchange and esterification of CH3COO with CH3O. A MgO powder featuring a Tasker III type (111) surface as its main exposed surface was produced after decomposition of the as-prepared Mg(OH)(OCH3) intermediate. X-ray diffraction (XRD) shows that the as-formed intermediate is Mg(OH)(OCH3), and methyl acetate is identified in the mother liquor by GCMS measurements. XRD, SEM, and TEM images also show that the surface of the MgO nanosheets is covered by a Tasker III (111) surface. The vanadia supported on this MgO (111) nanosheet surface is more active than the conventional MgO-supported system for the oxidative dehydrogenation of ethylbenzene with carbon dioxide, which is attributed to the oxygen-rich nature and intermediate basicity of the MgO (111) surface.