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Remarkable activity, selectivity and stability of innovative Ni catalysts for the CO2 methanation process

Siakavelas Georgios I., Charisiou Nikolaos D., Sebastian Victor, Hinder Steven J., Baker Mark A., Gentekakis Ioannis, Polychronopoulou Kyriaki, Goula Maria A.

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Περίληψη

This experimental study reports on the activity of Ni/CeO2, Ni/MxOy-CeO2 and Ni/La2O3-MxOy-CeO2(M= Mg2+) during the CO2 methanation reaction. The characterization of the supports and catalysts were performed using various characterization techniques, i.e., BET, H2-TPR, XRD, CO2-TPD and Raman spectroscopy. Sintering and possible coke formation on the catalyst surface were investigated via TEM analysis. The results showed that the modification of CeO2 with Mg2+ favoured the genesis of a separate phase of MgO increasing the moderate basic sites. Furthermore, the incorporation of La3+ ions into the crystal structure of CeO2 generated additional surface oxygenvacancy sites. Thus, the concurrently presence of La3+ and Mg2+ on the catalyst surface helped obtain a catalyst with increased basicity and surface oxygen vacancies, which accelerated the reaction of CO2 methanation at low temperature range. In terms of catalytic performance, the experimental results showed that at 350oC, the catalytic activity with regard to CO2 conversion was: Ni/La-Mg-Ce (50.0%) > Ni/Mg-Ce (43.0%) > Ni/Ce (39.0%) indicating that the catalytic performance depends on the physicochemical properties of the support, as well as, to the effect of the promoter (La3+ and Mg2+) on the CeO2 support. Finally, the Ni/La-Mg-Ce catalyst showed the highest catalytic activity in terms of the conversion of CO2 (50.0%), CH4 yield (50.0%) and the selectivity of CH4 (100%) at low temperature range.

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