Unveiling the potential of surfactant Pluronic-P123 application during the synthesis of Ni-hydrotalcite-derived catalysts for low-temperature CO2 methanation: A novel approach

For the tailoring purpose of NiMgAl-oxides (NMA) towards CO2 methanation, the surfactant Pluronic-P123 was first-time employed at different concentrations. Catalysts were examined by SEM-EDX, BET, XRD, H2-TPR, CO2-TPD, and TGA. By adding P123, a clear revolution in terms of the texture, morphology, and pore of catalysts was observed, which has never been recorded previously. The correlations between carbonate species and basic sites were identified thanks to in-situ CO2 sorption measurements. The stability of carbonate species was assumed to follow "hydrogen-carbonate < bidentate-carbonate < unidentate-carbonate < tridentate-carbonate". On the activity stand, 3P-NMA exhibited ca. 83.5% CO2 conversion and 99.5% CH4 selectivity at 300℃ vs. 46% and 97%, respectively, for the base case (GHSV = 12,000 h-1 , H2/CO2 = 4), alongside superior stability after a 16-hour of TOS run. Furthermore, Operando FTIR data revealed the appearance of formyl (*HCO) species under methanation conditions, allowing us to propose the reaction mechanism following *HCO formation as the key intermediate for CO2 methanation.