Synthesis and CO₂ Absorption Property of Li₄TiO₄ as a Novel CO₂ Absorbent

Abstract

Synthesis and CO₂ absorption property of Li₄TiO₄ oxide were studied by X-ray powder diffraction and thermogravimetry. Samples were prepared by the solid state method using Li₂CO₃ and Anatase or Rutile TiO₂ as starting reagents. From the results of XRD, it was found that single phase Li₄TiO₄ can be obtained from Anatase TiO₂ and Li₂CO₃ with 1 : 2.1 molar ratio in an alumina cell in atmosphere of Ar : H₂=80 vol% : 20 vol% gas mixture (150 mL/min of flow rate) by heat-treatment up to 1000°C with 5°C/min of heating rate. By the results of thermogravimetry, it was found that single phase Li₄TiO₄ can absorb CO₂ in the temperature range of 300°C to 856°C, and the maximum absorption is 42 mass% at 856°C. From the results of XRD, LiTiO_x and Li₂CO₃ phases were found in the Li₄TiO₄ sample after complete CO₂ absorption. Therefore, it is supposed that following reaction occurs in the reaction process between Li₄TiO₄ and CO₂. 42 mass% of the maximum absorption could be predicted on the basis of the reaction. Li₄TiO₄(s)+1.5CO₂(g)↔LiTiO_x(s)+1.5Li₂CO₃(s)+(2.5-x)/2 O₂(g) x=2~2.5