模板剂十二胺对胺改性HMS吸附CO2的影响

以正硅酸乙酯为硅源、十二胺为模板剂制备中孔硅HMS-1，采用焙烧和乙醇萃取的方法去除其模板剂，所得材料分别为HMS-2与HMS-3，并将四乙烯五胺（TEPA）与二乙醇胺（DEA）混合负载于3种材料上，采用X射线衍射（XRD）、傅里叶红外（FTIR）与氮气吸附实验对材料进行表征，研究改性前后的HMS对常压下低浓度CO₂的吸附性能及再生能力.XRD与FTIR结果表明，TEPA与DEA已被成功负载到HMS孔道内.氮气吸附实验表明，保留模板剂和胺基改性后，材料的孔容显著降低.20℃下，初始浓度为10%的CO₂在材料上的吸附量顺序为：MA-HMS-1（3.29mmol/g） > MA-HMS-3（2.7mmol/g） > HMS-1（1.88mmol/g） > MA-HMS-2（1.65mmol/g） > HMS-2（1.33mmol/g），模板剂的存在，不仅增加了CO₂的吸附位点，还对混合胺改性的HMS吸附CO₂起到了协同作用.在20~75℃范围内，MA-HMS-1与MA-HMS-3受温度影响最明显，65℃时吸附量达最大值；随着温度的升高，HMS-1的吸附量随温度升高持续降低；MA-HMS-2的吸附量基本不变.含胺基的4种材料（HMS-1、MA-HMS-1、MA-HMS-2与MA-HMS-3）在80℃下拥有优良的再生性能，经4次循环再生后，MA-HMS-1的再生率为97.5%，高于MA-HMS-2（83%）和MA-HMS-3（84%），保留HMS的模板剂对材料的再生性能有明显促进作用.

The influences of template dodecylamine on CO2 adsorption to Amine-modified HMS

The mesoporous silica HMS marked as HMS-1was prepared using tetraethyl orthosilicate as silica source and dodecylamine as template. Its template was removed by calcination and ethanol extraction. The materials without template was marked as HMS-2 (Calcined material) and HMS-3 (ethanol extraction). HMS-1, HMS-2 and HMS-3 were modified with mixed tetraethylenepentamine and diethanolamine. The structures of these materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and N₂ adsorption/desorption experiment. The adsorption properties and regeneration ability of the materials toward CO₂ with low concentration at atmosphere pressure were studied. The results of XRD and FTIR showed that TEPA and DEA were loaded into the pores of HMS successfully. The N₂ adsorption/desorption experiment showed that the pore volume of HMS-1 and modified HMS was significantly lower than that of HMS-2 and HMS-3. At 20^oC, the adsorption amount of CO₂ with initial concentration of 10% follows an order of MA-HMS-1 (3.29mmol/g) > MA-HMS-3 (2.7mmol/g) > HMS-1 (1.88mmol/g) > MA-HMS-2 (1.65mmol/g) > HMS-2 (1.33mmol/g), indicating that the template, diethanolamine, presented in HMS not only increases the adsorption sites, but also had synergistic effects on CO₂ adsorption to HMS functionalized with the mixed organic amines too. As temperature ranged from 20^oC to 75^oC, MA-HMS-1 and MA-HMS-3 adsorption were affected obviously and its amount reached the maximum at 65^oC. The adsorption amount of HMS-1 decreased consecutively with elevating temperature and MA-HMS-2 had almost a constant adsorption amount. The amine-containing materials, HMS-1, MA-HMS-1, MA-HMS-2 and MA-HMS-3, had excellent regeneration capability at 80^oC. After four times of continuous adsorption-desorption cycles, the regenerating ratio of MA-HMS-1 (97.5%) was much higher than that of MA-HMS-2 (83%) and MA-HMS-3 (84%), reflecting that the preserved template improved the regeneration capacity obviously.