Influence of components in the flue gas

https://doi.org/10.1016/j.gce.2021.11.009

“It is well known, components in flue gas, including O₂, H₂O, SO_x and NO_x, 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, NiO_x 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 SO_x and NO_x in flue gas will make the active catalytic metals in DFMs to be poisoned. Porta et al. [52] found that NO_x 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.”