苯基修饰的疏水微孔二氧化硅膜的制备与表征

Preparation and Characterization of Hydrophobic Microporous Silica Membranes Modified by Phenyl Groups

以苯基三乙氧基硅烷(PTES)和正硅酸乙酯(TEOS)为前驱体,通过溶胶-凝胶法制备了苯基修饰的SiO2膜材料.利用扫描电镜、N2气吸附、视频光学接触角测量仪、热重分析及红外光谱等测试手段对膜的孔结构及疏水性能进行了表征,研究了修饰后膜材料在室温条件下的单组分气体渗透和分离性能.结果表明,随着PTES加入量的增大,膜材料的疏水性逐渐增强,当PTES/TEOS和H2O/TEOS的摩尔比分别达到0.6和9.6时,膜材料对水的接触角达到115°±0.5°,仍保持良好的微孔结构,其孔体积为0.17cm3/g,孔径为0.4～0.5nm.室温下H2气在修饰后SiO2膜的输运既遵循发生在微孔孔道的表面扩散机理,又遵循发生在较大孔道或微缺陷的努森扩散机理.膜材料的H2气渗透率达到1.49×10-6mol/(m2·Pa·s),H2/CO2和H2/SF6的理想分离系数分别达到4.64和365.59.

Silica membranes modified with phenyl groups were synthesized through the acid-catalyzed co-hydrolysis and condensation reaction of tetraethyl orthosilicate（TEOS） and phenyltriethoxysilane（PTES）.The pore structure and hydrophobic properties of the modified silica membranes were characterized by means of SEM,nitrogen adsorption,water contact angle measurement,TG and FTIR.The single gas permeation and permselectivity of the hydrophobic silica membranes were also investigated at room temperature.The results show that the hydrophobic properties of the modified silica membranes are gradually enhanced with increasing amount of PTES in the mixture.When the molar ratio of PTES/TEOS increases to 0.6 and the molar ratio of H2O/TEOS to 9.6,the modified silica membranes exhibit an excellent hydrophobic property with a water contact angle of 115°±0.5° and a desirable microporous structure with a pore volume of 0.17 cm3/g and a sharp pore size distribution centered at 0.4-0.5 nm.The modified silica membranes conform to a combination of a surface diffusion mechanism associated with micropores and a Knudsen diffusion mechanism related to the larger pores or microcracks,with a H2 permeance of 1.49×10-6 mol/（m2·Pa·s） and a permselectivity of 4.64 for H2/CO2 and 365.69 for H2/SF6.