This work analyzes the CO chemical sorption on lithium cuprate (Li2CuO2) with a copper (II) ion substitution for 5 mol% of nickel (II), iron (III) or manganese (IV) ions into the crystalline structure. Li2CuO2 has good characteristics for CO2 capture and CO oxidation-capture, but the partial metal substitution modified its reactivity as bifunctional materials. Under CO (PCO=0.04) without oxygen presence, the 5Mn-Li2CuO2 solid solution presented a greater CO oxidation efficiency, owing to its structural contributions such as the facility to change the oxidation state to releasing oxygen (copper reduction) and the content of vacancies favoring the catalytic CO oxidation. When oxygen (PO2=0.04) was added, all solid solutions presented higher weight increments than the pristine Li2CuO2 sample. Also, the reduction in the crystal structures was avoided due to the Mars-van Krevelen mechanism, where ceramics acted as catalysts at moderate temperature and carbon oxides captors at higher temperatures, establishing them as bifunctional materials. Despite the copper ions have shown catalytic activity, Ni(II), Fe(III), and Mn(IV) presence in Li2CuO2 crystalline structure improved the catalytic properties. Nickel ions contributed to homolytic oxygen dissociation for carbonation, whilst the vacancies generated by Fe and Mn ions contributed to the Mars-van Krevelen mechanism. Also, the Mn4+ has a greater capacity to change its oxidation state in comparison to the other evaluated cations.

Bifunctionality of lithium cuprate solid solutions with three different transition metals: CO capture and oxidation with the effect of oxygen addition

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