(189e) High-Temperature CO2 Adsorption On LiXZrYOZ Ceramics

CO₂ is one of the major greenhouse gases (GHG) and the largest contributor to the global warming effects (about 60% in regard of its amount in the atmosphere), and coal-burning power plant is the major source of CO₂ generation with the typical CO₂ content about 10-13%, thus, CO₂ adsorption from the flue gas might be an effective approach for CO₂ Capture and Storage (CCS). Various materials have been proposed as CO₂ captors, including zeolites, carbon-based adsorbent, hydrotalcites and metal oxides. However, the temperature of the flue gas vent is about 573-773 K depended on various follow-up process of waste heat utilization, it is highly desired to separate CO₂ directly from flue gas at high temperature so as to use it as a feedstock for the synthesis of methanol and other chemicals, and the adsorbents should generally have high selectivity and adsorption capacity for CO₂ at high temperature, as well as good adsorption-regeneration kinetics and high multi-cycle stability. In this paper, pure monoclinic Li₆Zr₂O₇ and rhombohedral Li₈ZrO₆ with fraction of Li₆Zr₂O₇ are synthesized via co-precipitation method and characterized by SEM, TGA, and high-temperature CO₂ adsorption-desorption measurement. The adsorbents exhibit slow CO₂ uptake rate since the inhibited diffusion of CO₂ in the solid carbonate shell at T<973 K, as T>983 K (the Li₂CO₃ melting point), the CO₂ uptake rate enhances remarkably with 12.3% and 35.0% weight gain within 15 min at 1073 K respectively. The possible pathway of the adsorption process is further proposed. The Li₆Zr₂O₇ and Li₈ZrO₆ are promising candidates for CO₂ high-temperature adsorption.