用于分离CH_4/CO_2疏水性SiO_2膜的制备

Preparation of Hydrophobic Silica Membranes for Methane and Carbon Dioxide Separation

分别采用KH-570,KH-560和A-151代替部分TEOS作为前驱体,通过溶胶-凝胶法制备了疏水性SiO2气体分离膜,利用IR,BET,TG,SEM以及接触角测试仪等对其进行了表征,并对(0.8KH-570)SiO2膜进行了CH4/CO2气体渗透性能评价。结果表明,当A-151,KH-570和KH-560与TEOS的摩尔比均为0.8时,膜的接触角分别从28.6°增大到97.8,94.2°和90.7°。膜样品的疏水性增强,修饰后的膜孔径分布更加狭窄,平均孔径减小,抵抗水蒸汽的能力明显增强;膜层无开裂,表面完整。其中,KH-570修饰的膜性能较好,在n(KH-570)/n(TEOS)=0.8时,压力为30kPa的条件下,(0.8KH-570)SiO2膜对CH4/CO2的分离因子为2.13,大于纯SiO2膜的分离因子(1.58)和努森扩散理论的分离因子(1.67),分离效果较好。

Hydrophobic silica gas separation membranes were prepared by acid catalysed co-hydrolysis and condensation reaction of tetraethylorthosilicate （TEOS） and 7-methacryloxypropyltrimethoxy- silane（KH-570） or 7-glycidyltrimethoxysilane（KH-560） or vinyl triethoxysilane in ethanol,character- ized by IR,BET,TG-DTG , SEM, the measurement of contact angle,and （0.8KH-570） silica mem- branes were evaluated by CH4/CO2 gas permeability. The results showed that,as the molar ratio of A- 151/TEOS, KH-570/TEOS and KH-560/TEOS increased to 0.8, it was found that the water contact angle were respectively 97.8,94.2°and 90.7°, and the unmodified membrane was only 28.6°. The hy- drophobicity of modified membrane samples enhanced. Modified silica membranes had a desirable pore structure, pore size distribution was more narrow and pore width gradually reduced. In the moisture environment , modified silica membranes could be better for resisting water vapor than the unmodified silica membranes. Modified silica membranes were basically free crack, and the surfaces were integrat- ed. Modified silica membrane by KH 570 was best. For the modified silica membranes with KH-570/ TEOS molar ratio of 0.8,CH4/CO2 separation factor with the pressure at 30kPa was 2.13, slightly larger than pure silica membrane separation factor （1.58）and the theoretical separation factor（1.67） by Knudsen diffusion. It had a better separation performance.