Tri-lithium borate (Li3BO3); a new highly regenerable high capacity CO2 adsorbent at intermediate temperature

Abstract

A lithium-borate oxide, Li₃BO₃, is proposed as a next generation high capacity CO₂ adsorbent operative over the intermediate temperature range of 500 to 650 °C. This adsorbent shows high CO₂ uptake capacity (e.g., 11.3 mmol g⁻¹ at 520 °C) with excellent cyclic regenerability in the presence of alkali-metal nitrite salts as a reaction facilitator. The high CO₂ uptake is attributed to the dissociative formation of lithium carbonate (Li₂CO₃) and different compositions of lithium borates (Li₆B₄O₉, LiBO₂ and Li₂B₄O₇) during the reaction of Li₃BO₃ with CO₂. The excellent performance of the new CO₂ adsorbents is discussed in terms of rapid gas–solid reactions on Li₃BO₃ mediated by the molten nitrite salts and pinning effects that prevent the sintering of particle grains.