Abstract
Ni/oxide-SiO2 (oxide: MgO, CeO2, La2O3, 10 wt.% target concentration) catalyst samples were prepared by successive impregnation of silica matrix, first with supplementary oxide, and then with Ni (10 wt.% target concentration). The silica matrix with multimodal pore structure was prepared by solvothermal method. The catalyst samples were structurally characterized by N2 adsorption-desorption, XRD, SEM/TEM, and functionally evaluated by temperature programmed reduction (TPR), and temperature programmed desorption of hydrogen (H2-TPD), or carbon dioxide (CO2-TPD). The addition of MgO and La2O3 leads to a better dispersion of Ni on the catalytic surface. Ni/LaSi and Ni/CeSi present a higher proportion of moderate strength basic sites for CO2 activation compared to Ni/Si, while Ni/MgSi lower. CO2 methanation was performed in the temperature range of 150–350 °C and at atmospheric pressure, all silica supported Ni catalysts showing good CO2 conversion and CH4 selectivity. The best catalytic activity was obtained for Ni/LaSi: CO2 conversion of 83% and methane selectivity of 98%, at temperatures as low as 250 °C. The used catalysts preserved the multimodal pore structure with approximately the same pore size for the low and medium mesopores. Except for Ni/CeSi, no particle sintering occurs, and no carbon deposition was observed for any of the tested catalysts.
Highlights
Efficient CO2 transformation in useful and value-added compounds is the most promising way of action for the abatement of CO2 elimination in the environment, and, eventually, for diminishing its negative effects on the climate change
A similar improvement of the catalytic performances for the lanthana containing catalysts compared to the unpromoted ones were observed in these studies, but a direct comparison of the results reported in these papers with the ones obtained in this work is difficult due to the differences in the composition and employed reaction conditions for both catalysts
The slight improvement in methane selectivity can be due to the ceria activity for the water gas shift (WGS) reaction, and subsequent inhibition of the reverse water gas shift (RWGS) reaction (CO2 +H2 →CO+H2 O) [50]. This behavior of Ni/CeSi is opposite to the results recently reported for CO2 methanation using Ni-CeO2 -SiO2 [28], Ni-CeO2 -MCM-41 [25], and Ni-CeO2 -SBA-16 [26], for which the ceria containing catalysts presented significantly better results than the Ni/silica counterparts, especially at low temperatures
Summary
Efficient CO2 transformation in useful and value-added compounds is the most promising way of action for the abatement of CO2 elimination in the environment, and, eventually, for diminishing its negative effects on the climate change. In this regard, the methanation of CO2 (Sabatier reaction): Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in CO2 + 4H2 → CH4 + 2H2 O. Which generates synthetic methane, has re-gained great interest in the last decade [1]. The development of active catalysts is vital for the practical applications of this reaction [2,3]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
