Na掺杂对硅酸锂吸收CO_2性能的影响

Effect of Na-doping on CO_2 Absorption of Li_4SiO_4

通过高温固相反应法,在添加不同比例Na2CO3的条件下,合成出一系列可在高温500～750℃之间直接吸收CO2的硅酸锂材料.利用扫描电子显微镜、X射线粉末衍射仪分别观察和评价了合成材料的表面形貌与结构特征,用热重分析仪测量了硅酸锂材料的CO2吸收性能.实验结果表明,通过适量Na元素的掺杂,能够提高硅酸锂材料吸收CO2的性能,当Na2CO3的添加量x=0.02时,合成的硅酸锂材料在CO2气氛下,于700℃恒温保持约15min即可达到吸收平衡,材料的吸收量为(46±0.6)%(w),与未经掺杂的材料相比,吸收容量有所提高.此外,气氛中CO2的浓度对材料吸收CO2的速率有较大影响.

Sodium-doped lithium silicate as CO2 absorbent at 500℃ to 750℃ was prepared by high-temperature solid-state reaction. The influence of sodium doping on the crystal structure of the absorbent was studied by X-ray diffraction （XRD）. The microscopic morphologies of the absorbents were observed by scanning electron microscopy （SEM）. The CO2-absorption capacities were measured by a thermogravimetric analyzer, which showed that sodium doping could improve the COz-absorption ability of lithium silicate. It was found that the absorbent possessed the best performance when n（SiO2）：n（Li2CO3）：n（Na2CO3）=1： 1.96：0.04. The maximum amount of CO2 absorption arrived at （46±0.6）%（w） in CO2 atmosphere at 700℃ within 15 min. Moreover, the CO2 concentration in gas phase influenced the rate of CO2 absorption.