engleski

Combustion synthesis of MOx-CeO2-Al2O3 nanocatalyst

Cerium oxide (CeO2) is a technologically important semiconducting material which exhibits high mixed ionic and electronic conductivity, as well as high oxygen storage capacity due to the reversible redox reaction between Ce4+ and Ce3+ions within the ceria crystal lattice. One of the most notable applications of ceria is as a catalyst in three-way catalytic converters in automobile exhaust systems. Ceria interaction with alumina can help in the stabilization of the surface area of the γ-Al2O3 support through the formation of cerium aluminate (CeAlO3). Ceria is also used in solid oxide fuel cells (SOFCs), but its drawback is a lack of mechanical stability which can be improved by adding alumina. Literature shows that mixing ceria with other catalytically active substances like MnOx, CuO or noble metals like Pd can significantly enhance its catalytic performance in many chemical processes. Therefore, the goal of this research was to produce and characterize MOx-CeO2-Al2O3 mixed oxides. The method of choice was combustion synthesis with glycine as fuel, since we have gained favorable results in producing γ-alumina in this manner in our previous work. As-prepared samples of pure Al2O3, CeO2 and MnOx, as well as corresponding mixed oxides were synthesized and characterized by X-ray diffraction analysis (XRD), differential thermal and thermogravimetric analysis (DTA-TGA), Fourier transformed infrared spectroscopy (FTIR) and nitrogen adsorption/desorption isotherms. For mixed oxides, CeAlO3 phase was achieved. However, not all as-prepared samples were crystalline and all of them showed presence of residual nitrates on FTIR spectra, which is why thermal treatment at 800 °C for 2 hours was applied. Thermal treatment yielded with mixed oxides having crystallite sizes in the nano range and their catalytic activity was tested on the soot oxidation process.

combustion synthesis ; ceria ; alumina ; nanocatalyst

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