Alkali Metal Nitrate-Promoted High-Capacity MgO Adsorbents for Regenerable CO₂ Capture at Moderate Temperatures

Regenerable high capacity CO 2 sorbents are desirable for the establishment of widespread carbon capture and storage (CCS) systems to reduce global CO 2 emissions. We report on the marked effects of molten alkali metal nitrates on CO 2 uptake by MgO particles and their impact on the development of highly regenerable CO 2 adsorbents with high capacity (>10.2 mmol g –1 ) at moderate temperatures (∼300 °C) under ambient pressure. The molten alkali metal nitrates are shown to prevent the formation of a rigid, CO 2 -impermeable, unidentate carbonate layer on the surfaces of MgO particles and promote the rapid generation of carbonate ions to allow the high rate of CO 2 uptake.