Influence of components in the flue gas

“It is well known, components in flue gas, including O2, H2O, SOx and NOx, will affect the adsorption and catalytic performance of DFMs. Considering industrial cost, Ni is the promising catalytic candidate for DFMs. However, Ni-based DFMs cannot achieve efficient methanation after CO2 capture from the flue gas containing O2. This limitation is attributed to the fact that when exposed to the O2 atmosphere in the flue gas during CO2 capture, NiOx cannot be reduced to active catalytic Ni0 species under operating conditions at 320 °C. Therefore, doping with small amounts of additives such as precious metals of Ru, Rh [51], and other transition metals can be a solution to improve the oxidation resistance of Ni-based DFMs. While SOx and NOx in flue gas will make the active catalytic metals in DFMs to be poisoned. Porta et al. [52] found that NOx preferentially adsorbs on BaO over CO2 due to its higher acid character. What is worse, nitrates are difficult to be decomposed which significantly hinders the CO2 capture. H2O is another important parameter that has a significant impact on the recycle performance of CO2 adsorption and methanation. Miguel et al. [17] found that the presence of H2O can promote CH4 formation, which in turn participated in CO2 desorption, making it faster and removing more CO2 for the regeneration of adsorption sites than under dry conditions.”

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