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

Regenerable high capacity CO2 sorbents are desirable for the establishment of widespread carbon capture and storage (CCS) systems to reduce global CO2 emissions. We report on the marked effects of molten alkali metal nitrates on CO2 uptake by MgO particles and their impact on the development of highly regenerable CO2 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, CO2-impermeable, unidentate carbonate layer on the surfaces of MgO particles and promote the rapid generation of carbonate ions to allow the high rate of CO2 uptake.