The synthesis and characterization of Ni-M-Tb/ Al2O3 (M: Mg, Ca, Sr and Ba) nanocatalysts prepared by different types of doping using the ultrasonic- assisted method to enhance CO2 methanation

In the present study, Ni-M-Tb/Al2O3 (M: Mg, Ca, Sr and Ba) nanostructured catalysts with different ratios of the alkali metals were synthesized by the ultrasonic-assisted one-pot method. The catalytic performance was investigated in terms of CO2 conversion, CH4 selectivity, and stability via the H2-TPR analysis. The structural properties were delineated using XRD, SEM, TEM and BET equation. The results showed that the 2Ni-5Mg-5Tb/Al2O3 catalyst with a maximum CO2 conversion of 75.37% and CH4 selectivity of 100%, at the operating temperature of 400 degrees C in the molar ratio of H2:CO2:3.5 for 100 h, had the best performance. This could benefit from the particular electronic structure of Tb in combi-nation with Mg and Ni, reducing agglomeration, as demonstrated by the SEM and BET results. Based on the current findings, novel catalysts with high conversion efficiency of CO2 to CH4 might be achieved by tuning a decent combination of alkaline and rear earth elements as the promoters of Ni-based catalysts. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The present study synthesized Ni-M-Tb/Al2O3 (M: Mg, Ca, Sr, and Ba) nanostructured catalysts with different ratios of alkali metals by the ultrasonic-assisted one-pot method. The catalytic performance was evaluated through H2-TPR analysis, and the structural properties were characterized by XRD, SEM, TEM, and BET equation. The 2Ni-5Mg-5Tb/Al2O3 catalyst exhibited the highest CO2 conversion of 75.37% and CH4 selectivity of 100% at 400 degrees C with a molar ratio of H2:CO2:3.5 for 100 hours, attributed to the unique electronic structure of Tb in combination with Mg and Ni, which minimized agglomeration according to SEM and BET results. These findings suggest that tuning the combination of alkali and rare earth elements as promoters in Ni-based catalysts could lead to novel catalysts with high CO2 conversion efficiency to CH4.