Structuring NiRuCa Dual Function Material for Real Emissions Scenarios in CO2 Capture and Methanation

Abstract For industrial deployment, dual function materials must show stability and efficiency under real-world emissions, in particular maintaining their performance in the presence of oxygen, water and other impurities. Toward this aim, we scaled up the synthesis of NiRuCa/Ce/Al with varying compositions to yield pellet-like spherical DFMs for the methanation of CO2 emissions and evaluated their activity under real conditions anticipated for ICCU. We first tested the effects of oxygen and water on performance, then evaluated DFM performance when CO2 capture was performed in a stream consisting of real biogas emissions produced via anaerobic digestion. Using operando DRIFTS-MS, we were able to determine that ICCU in the presence of O2, H2O, CH4 and a mixture of those alongside CO2 in the adsorption step mechanistically distinguishes itself from ideal conditions, with H2O having the most detrimental effect for CO2 capture and subsequent methane production. However, O2 can suppress the negative effect of H2O by oxidizing the reduced metallic sites and inhibiting the dissociation of CO2 in the adsorption step. The DFM formulation that yielded the best performance (258.97 μmol/g DFM) in the presence of oxygen and water was NiRuCa/Al. The enhanced activity is associated with better metal dispersion and higher medium basic sites. NiRuCa/Al also demonstrated better CO2 ICCU-methanation, 328.3 μmol/g DFM, when using biogas, marking the first report of such performance under real-world conditions. The postreaction characterisations showed no significant changes in material distribution, morphology and composition, indicative of structural stability and potential for adoption into practical ICCU under industrial conditions.