Unveiling the dynamic CO 2 capture performance of MgO promoted with molten salts and CaCO 3 via fixed bed reactor experiments

MgO promoted with molten alkali salts and CaCO 3 displayed efficient CO 2 capture activity in a fixed bed reactor, attaining 75% CO 2 removal at 275 °C and stable cyclic performance, with the promoters providing an alternative carbonation mechanism. Carbonate looping using MgO-based materials has recently ignited scientific interest for CO 2 capture at intermediate temperatures (275–375 °C), with the main limitation being the slow carbonation kinetics of MgO. Molten alkali nitrates and metal carbonates have been identified as promoters that provide an alternative reaction mechanism for an enhanced carbonation rate. However, the evaluation of the ability of these materials to effectively remove CO 2 from a gas feed under realistic reactor configurations is still required. This study investigated the CO 2 capture performance of magnesite-derived MgO promoted with limestone and molten Li, Na and K nitrates under carbonate looping conditions in a fixed bed reactor. The CO 2 capture efficiency was enhanced in the presence of H 2 O, by increasing the gas–solid contact time and by decreasing the carbonation temperature. The evaluation demonstrated that ∼75% CO 2 stripping of a gas feed with 30% CO 2 concentration at 275 °C and a space velocity of 300 h −1 is possible, a performance that highlights and expands the potential and possible applications of MgO-based materials.