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