锂离子筛前驱体Li4Mn5O12的制备及性能研究

吸附法是目前从低锂浓度的盐湖卤水中提取锂的最有前途的方法。采用EDTA-柠檬酸络合法制备了Li₄Mn₅O₁₂前驱体, 经酸浸脱锂后得到对Li⁺具有特殊选择性的锰氧化物锂离子筛。通过热重、XRD、SEM、FT-IR、化学组成、吸附动力学及共存金属离子的分配系数等手段对样品的晶相结构和Li⁺选择性吸附性能进行了研究。结果表明: 煅烧时间对Li₄Mn₅O₁₂前驱体生成有较大影响, 由400℃煅烧24 h所得的前驱体几乎为纯相的Li₄Mn₅O₁₂化合物, 经酸浸脱锂后的离子筛仍保持着与前驱体相同的尖晶石结构; 前驱体Li₄Mn₅O₁₂和离子筛MnO₂均为 200 nm左右的球状颗粒; 离子筛的最大吸附容量为43.1 mg/g, 并具有较好的Li⁺选择性。

Synthesis and Properties of Lithium Ion-sieve Precursor Li4Mn5O12

Adsorption method is the most promising method for extraction of lithium from salt lakes. A new kind of MnO₂ ion-sieves with high Li⁺ selective adsorption property were synthesized. Spinel-type Li₄Mn₅O₁₂ precursors were synthesized by EDTA-citrate complexing method using LiNO₃ and Mn(NO₃)₂·4H₂O as starting materials. MnO₂ ion-sieves with Li⁺ selective adsorption property were prepared by the acid treatment process to extract Li⁺ from the spinel Li₄Mn₅O₁₂ precursors. As-prepared samples were characterized by thermo gravimetric, XRD, SEM, FT-IR and Li⁺ selective adsorption measurements, respectively. The results show that calcination time has a considerable effect on the structure and composition of precursors. The precursor calcined at 400℃ for 24 h has a pure phase of Li₄Mn₅O₁₂. Final MnO₂ ion-sieve and Li₄Mn₅O₁₂ precursor are about 200 nm spherical pellets and have the same structure of spinel. The maximum adsorption capacity of ion-sieve is about 43.1 mg/g and has the good selection for Li⁺.