疏水微／介孔材料的合成及其对苯及其同系物的吸附

Synthesis of the micro/mesoporous materials and its application on the adsorption of benzene and its derivatives

以含氢聚甲基硅氧烷(PMHS)、正硅酸乙酯(TEOS)为硅源,在室温、无模板剂条件下合成了一种疏水微孔/介孔材料,通过调节PMHS/TEOS的比例,获得了3种具有不同微孔、介孔比例的多孔材料。并通过N2吸附/脱附、HRTEM、热重等手段对上述3种材料的结构特征及热稳定性进行了表征。结果发现,所得材料均具有微孔和介孔两种孔隙结构,且具有良好的热稳定性和疏水性,在500℃以下不会发生热分解。进一步利用脉冲色谱技术研究了上述3种材料对苯及其同系物的热力学吸附行为。结果表明,上述3种材料均能够实现苯及其同系物的完全分离,相应的亨利常数、吸附热、分离因子的大小顺序为:正丁基苯>正丙基苯>乙苯>甲苯>苯,且随着PMHS/TEOS比例的增加,亨利常数、吸附热以及分离因子都增加。

In the present work, micro/mesoporous silica modified with methyl groups was prepared via the non-surfactant method using tetraethylorthosilicate （TEOS） and polymethylhydrosiloxane （PMHS） as silica sources, and their structural properties were characterized with N2 adsorption/desorption, High Resolution Transmission Electron Microscopy （HRTEM） and thermogravimetric analysis （TG）. The results showed that the prepared products were micro/mesoporous materials with high hydrophobility and thermal stability. Three micro/mesoporous materials with different micropore/mesopore ratios were prepared by adjusting the mass ratio of PMHS/TEOS, and the separation performance of benzene and its derivatives on the three materials were further studied by using the pulse chromatography technique. Benzene and its derivatives can be fully separated on the micro/mesoporous materials, and the retention time increased with the increase of the mass ratio of PMHS/TEOS. Henry constant, adsorption heat, separation factors followed the same order： n-butylbenzene〉n-propylbenzene〉ethylbenzene〉toluene〉benzene. Henry constant, adsorption heat, separation factors increased with the increase of the mass ratio of PMHS/TEOS.