Synthesis and Characterization of Magnesium Oxide Supported Catalysts with a Meso-Macropore Structure

Abstract

Nanostructured magnesium oxide catalyst support materials with controlled morphology and size were synthesized from a supercritical carbon dioxide/ethanol solution via chemical reaction of soluble precursors and subsequent thermal decomposition. Leaf-like magnesium hydroxide precursors with high specific surface area were formed by a low-temperature chemical reaction at below 140 °C, while magnesium carbonate cubes with a very low surface area less than 3.3 ㎡/g were formed by temperature-induced phase transition from a loose to a dense structure during carbonation reaction at above 150 °C. The specific surface area has significantly increased higher than 90 ㎡/g due to the creation of highly porous MgO cubes with mesopore structure formed after thermal decomposition of the magnesium carbonate precursors. Ni-magnesium oxide catalysts with bimodal pore structure were finally formed by the consequence of packing heterogeneity of the porous magnesium oxides with different morphologies and sizes.