液相法结合冷冻干燥技术制备Li<sub>4</sub>SiO<sub>4</sub>材料及其高温二氧化碳吸收性能

Abstract

选用LiOH∙H2O、LiNO3、Li2CO3为锂源，硅溶胶为硅源，采用液相法结合冷冻干燥技术制备了Li4SiO4材料，采用热重分析(TGA)研究了Li4SiO4前躯体的失重行为，采用X射线粉末衍射仪(XRD)和扫描电子显微镜(SEM)对Li4SiO4材料的结构和形貌进行分析。在热重分析仪(TGA)上考察了制备材料的高温CO2吸收性能，发现以LiOH∙H2O为锂源时，合成材料的吸收性能最好。考察了该材料在不同温度、不同CO2分压下的高温CO2吸收性能，结果表明，在吸收温度为550℃，CO2分压为0.25 bar时，样品在5 min时吸收量为24.1 wt%，10 min内即可达到吸收平衡，平衡吸收量为29.9 wt%。经过5次吸收-解吸后，吸收速率、吸收量都没有出现明显下降。 A liquid phase method combined with the freeze-drying technique was developed to synthesize Li4SiO4 materials using LiOH∙H2O, LiNO3, Li2CO3 and silica sol as the lithium and silicon sources, respectively. The weight loss behaviors of the prepared Li4SiO4 precursors were investigated by the thermal gravimetric analysis (TGA). The structure and morphology of the prepared Li4SiO4 materials were characterized by XRD and SEM, respectively. The CO2 absorption properties of prepared Li4SiO4 were investigated by thermal gravimetric analysis (TGA). The results show that the Li4SiO4 material prepared using LiOH∙H2O as the lithium source presents the best CO2 absorp-tion property among the prepared Li4SiO4 materials. The CO2 absorptions at different temperatures and different CO2 partial pressures have been performed on the optimized Li4SiO4 material. The absorbed amount of CO2 reaches 24.1 wt.% within 5 min and an equilibrium amount of 29.9 wt.% is achieved within 10 min at 550˚C and a partial pressure of 0.25 bar. Additionally, after five absorption-desorption cycles, the sorbent still maintains its original properties in terms of capture rate and absorption amount.