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

Abstract

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 °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 combination 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.