Morphology control of ceria nanocrystals for catalytic conversion of CO2 with methanol

Abstract

This paper describes the synthesis of ceria catalysts with octahedron, nanorod, nanocube and spindle-like morphologies via a template-free hydrothermal method. The surface morphologies, crystal plane and physical-chemical structures were investigated via field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and temperature-programmed desorption of ammonia and carbon dioxide (NH₃-TPD and CO₂-TPD). The catalytic performance over these ceria catalysts with different exposed planes were tested for dimethyl carbonate (DMC) synthesis from CO₂ and methanol. The results showed that the spindle-like CeO₂ showed the highest DMC yields, followed by nano-rods, nano-cubes and nano-octahedrons. A synergism among the exposed (111) plane, defect sites, and acid-basic sites was proposed to be crucial to obtaining the high reactivity of DMC formation.