K元素的掺杂对锆酸锂材料吸收CO_2性能的影响

Effect of Doping K Element on Properties of Lithium Zirconate as CO_2-absorbent

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———Li2K2xZrO3(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。

With nanometer-sized monoclinic ZrO2, lithium carbonate, and potassium carbonate as starting materials, potassium-doped lithium zirconate Li2K2xZrO3 (0 [less-than or equal to] x [less-than or equal to] 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 Li2K2xZrO3 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°C within 160 min. 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.