K元素的掺杂对锆酸锂材料吸收CO2性能的影响

以纳米级单斜相ZrO₂为反应物，采用高温固相合成法在K元素掺杂的情况下，制备了一系列可在高温460～650℃下直接吸收CO₂的锆酸锂材料——Li₂K_2xZrO₃（0≤x≤0.4）。采用扫描电镜（SEM）、X-射线衍射仪（XRD）以及热重分析仪（TG）分别进行了形貌、结构以及吸收CO₂性能的分析。实验结果表明，通过适量K元素的掺杂，能明显改善材料吸收CO₂的性能，当K₂CO₃的添加量x=0.03时，制备的材料具有较快的吸收速度和较好的吸收容量，在500℃、20% CO₂（80%空气）的气氛下保持160min即可达到吸收平衡，吸收量可达（25±0.6）%（wt），而且材料的循环性能也较好。

Effect of Doping K Element on Properties of Lithium Zirconate as CO2-absorbent

With nanometer-sized monoclinic ZrO₂, lithium carbonate, and potassium carbonate as starting materials, potassium-doped lithium zirconate Li₂K_2xZrO₃ (0≤x≤0.4) absorbents are prepared by high-temperature solid-state reaction. The influence of doping potassium on the crystal structure of the prepared absorbents is studied by comparison of their XRD patterns. The microscopic morphologies of absorbents with different x were viewed by a sanning electron microscopy. Their CO₂ absorption abilities were measured with a thermogravimetric analyzer. The experimental results show that doping potassium can significantly improve the CO₂ absorption ability of lithium zirconate. It is found that Li₂K_2xZrO₃ absorbent with x=0.03 possesses the best performance. As much as (25±0.6)% (wt) of CO₂ was absorbed by such an absorbent from an atmosphere consisting of 20% of CO₂ plus 80% of air at 500℃ within 160min. After 18 absorption-desorption cycles this absorbent lost only 1.1% of its CO₂-absorption capacity. Since no remarkable change in particle size is observed, the performance improvement might be attributed to the creation of lattice defects in the lithium zirconate crystals by doping potassium.