陈化温度和pH值对氨基功能化介孔氧化硅吸附CO_2性能的影响

本研究采用溶胶-凝胶法,分别以十二烷基肌氨酸钠、氨丙基三甲氧基硅烷(APTMS)和正硅酸乙酯(TEOS)为结构导向剂(SDA)、共结构导向剂(CSDA)和硅源合成了氨基功能化的介孔氧化硅预产物。利用乙醇和乙醇胺混合液对预产物进行萃取后获得氨基功能化介孔氧化硅。利用红外光谱、元素分析、N2吸-脱附、透射电镜等手段对材料进行了表征。红外光谱结果证明通过萃取方法可较好地去除表面活性剂;N2吸附结果表明所有样品都具有介孔结构;元素分析和透射电镜结果说明反应陈化温度、pH值等合成条件对材料孔道内表面的氨基含量和材料结构有较大的影响。CO2吸附实验证明在低陈化温度、相对较低的pH值下合成的材料具有较高的CO2吸附量。

Effects of Aging Temperature and pH Value on Adsorption Properties of Amino-Functionalized Mesoporous Silicas for CO2

Using N-lauroylsarcosine sodium, 3-aminopropyltrimethoxysilane and TEOS as structure-directing agent (SDA), co-structure-directing agent (CSDA) and silicon source, respectively, the precursors of amino-functionalized mesoporous silicas were prepared by a sol-gel method. The amino-functionalized mesoporous silicas were obtained via the precursors extracted with a mixture solution of ethanol and ethanol amine. The resulting mesoporous silicas were characterized by the FTIR, N2 adsorption-desorption, elemental analysis, and TEM techniques. The FTIR characterization indicates that the surfactant can be efficiently removed by the solvent extraction. A mesoporous structure is available in the synthesized materials, confirmed by the characterization of N₂ adsorption-desorption. The results from both elemental analysis and TEM characterizations show that the amount of amino groups inside the mesoporous materials is greatly controlled by the aging temperature and pH value of the synthetic solution. The adsorption of CO₂ on the synthesized materials implies that the low aging temperature and relatively low pH value of the synthetic solution would be beneficial to enhance the adsorbed amount of CO₂ on the resulted materials.