Gas Separation Silica Membranes Prepared by Chemical Vapor Deposition of Methyl-Substituted Silanes
Gas Separation Silica Membranes Prepared by Chemical Vapor Deposition of Methyl-Substituted Silanes
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DOI：
10.3390/membranes9110144
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发表时间：
2019-11-01
期刊：
影响因子：
4.2
通讯作者：
Oyama, S. Ted
中科院分区：
文献类型：
--
作者：
Kato, Harumi;Lundin, Sean-Thomas B.;Oyama, S. Ted
研究了甲基官能团的存在对二氧化硅膜透气性和结构形貌的影响。采用化学气相沉积法（CVD）在650℃和常压下合成了三种具有不同甲基和甲氧基官能团的硅化合物：正硅酸四甲基（TMOS）、甲基三甲氧基硅烷（MTMOS）和二甲氧基硅烷（DMDMOS）。对不同前驱体在CVD过程中的停留时间进行了调整，并根据气体渗透率和理想气体选择性标准进行了优化。TMOS-、MTMOS-和dmdmos衍生膜在600℃下的H-2最终渗透率分别为1.7 × 10（-7）、2.4 × 10（-7）和4.4 × 10(-8) mol中心点m（-2）中心点s（-1）中心点Pa-1和H-2/N-2选择性分别为990、740和410。用傅里叶变换红外光谱（FTIR）证实了MTMOS和DMDMOS前驱体制备的膜中存在甲基。FTIR分析表明，二氧化硅结构中甲基信号的增加与水热稳定性的提高和氢渗透表观活化能的增加有关。此外，几种气体（He, H-2, Ne, CO2， N-2和CH4）的渗透机制通过拟合气体渗透温度依赖于三种模型之一来确定：固态，气体平移或表面扩散。
The effect on the gas permeance properties and structural morphology of the presence of methyl functional groups in a silica membrane was studied. Membranes were synthesized via chemical vapor deposition (CVD) at 650 degrees C and atmospheric pressure using three silicon compounds with differing numbers of methyl- and methoxy-functional groups: tetramethyl orthosilicate (TMOS), methyltrimethoxysilane (MTMOS), and dimethyldimethoxysilane (DMDMOS). The residence time of the silica precursors in the CVD process was adjusted for each precursor and optimized in terms of gas permeance and ideal gas selectivity criteria. Final H-2 permeances at 600 degrees C for the TMOS-, MTMOS-, and DMDMOS-derived membranes were respectively 1.7 x 10(-7), 2.4 x 10(-7), and 4.4 x 10(-8) mol center dot m(-2)center dot s(-1)center dot Pa-1 and H-2/N-2 selectivities were 990, 740, and 410. The presence of methyl groups in the membranes fabricated with the MTMOS and DMDMOS precursors was confirmed via Fourier-transform infrared (FTIR) spectroscopy. From FTIR analysis, an increasing methyl signal in the silica structure was correlated with both an improvement in the hydrothermal stability and an increase in the apparent activation energy for hydrogen permeation. In addition, the permeation mechanism for several gas species (He, H-2, Ne, CO2, N-2, and CH4) was determined by fitting the gas permeance temperature dependence to one of three models: solid state, gas-translational, or surface diffusion.