(513aj) Structure-Activity Relationship of Nanostructured Ceria for the Catalytic Conversion of Methanol and Carbon Dioxide to Dimethyl Carbonate

The synthesis of dimethyl carbonate (DMC) from CO₂ has attracted much attention due to its extensive applications and interesting properties such as high boiling point, biodegradability and non-corrosiveness.[1–3] In this study, ceria (CeO₂) with three different shapes (nanooctahedra, nanocubes, nanorods) were synthesized via hydrothermal method and screened for carbonylation reaction. Off these three shapes of nanostructures, the nanorod was doped with various metal oxides such as CaO, NiO, CuO, and CoO by wet impregnation method. The catalysts were characterized by X-ray diffraction (XRD), NH₃/CO₂-TPD, X-ray fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), and N₂ physisorption to determine the crystal size and phases, acid-base properties, metal loading, and surface properties. The obtained materials were employed as catalysts for the activation of carbon dioxide (CO₂) and methanol carbonylation reaction to dimethyl carbonate (DMC) at 140 °C and 30 bar for a reaction duration of 3 h. It was found that the shape of the nanostructured ceria affects the DMC yield with the CeO₂ nanorod catalyst producing the highest DMC yield (1.6 mmol) followed by nanooctahedra (1.5 mmol) and nanocubes (1.0 mmol). The catalytic tests showed 100 % DMC selectivity and the trends of catalytic activity over ceria-doped metal oxide decreased in the following order: CeO₂ > CoO/CeO₂ > NiO/CeO₂ > CaO/CeO₂ > CuO/CeO₂. The material characterization and evaluation results suggest that CeO₂ nanorod (111) interface increased the surface basicity and activity of CO₂ hydrogenation to methanol while the CeO₂ octahedral sites enhanced the stability of catalyst.

[1] M.A. Atanga, F. Rezaei, A. Jawad, M. Fitch, A.A. Rownaghi, Appl. Catal. B Environ. 220 (2018) 429–445.

[2] A. Al-Mamoori, A. Krishnamurthy, A.A. Rownaghi, F. Rezaei, Carbon Capture and Utilization Update, Energy Technol. 5 (2017) 834–849

[3] J. Al-Darwish, M. Senter, S. Lawson, F. Rezaei, A.A. Rownaghi, Catal. Today. (2019) 0–1. https://doi.org/10.1016/j.cattod.2019.06.013.