Promotion of CO_2 methanation at low temperature over hydrotalcite-derived catalysts-effect of the tunable metal species and basicity

摘要

The CO2 methanation is an effective strategy for making full use of waste gases and converting them into valuable chemicals. Nowadays, the key challenge is the design of efficient catalysts to enhance low-temperature catalytic performance. A series of hydrotalcite-derived catalysts with tunable metal species were prepared by hydrothermal synthesis method for CO2 methanation at low-temperature. It was found that suitable synergistic effect between metallic Ni and basic sites in the support could be achieved by regulating the metal composition of hydrotalcite-derived catalysts. The NiMgAl catalyst exhibited the highest catalytic activity with CO2 conversion of 91.8% at 250 degrees C. The in situ DRIFTS measurements and DFT calculation further revealed that the alkaline metal oxide MgO and more Ni(111) active sites in the NiMgAl catalyst could promote the activation of CO2 and the formation of active intermediates, which actively participated in improving lowtemperature activity. Therefore, the ternary mixed oxides catalyst derived from LDHs precursors shows a potential strategy in achieving excellent catalytic properties for CO2 methanation at low-temperature. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.