TY - JOUR
T1 - Gas separation silica membranes prepared by chemical vapor deposition of methyl-substituted silanes
AU - Kato, Harumi
AU - Lundin, Sean Thomas B.
AU - Ahn, So Jin
AU - Takagaki, Atsushi
AU - Kikuchi, Ryuji
AU - Oyama, S. Ted
N1 - Funding Information:
Funding: This research was supported by a fellowship from the Japan Society for the Promotion of Science, JSPS KAKENHI Grant Number JP17F17772, and by the Japan Science and Technology Agency under the CREST program, Grant Number JPMJCR16P2.
Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2019/11
Y1 - 2019/11
N2 - 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◦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 H2 permeances at 600◦C for the TMOS-, MTMOS-, and DMDMOS-derived membranes were respectively 1.7 × 10−7, 2.4 × 10−7, and 4.4 × 10−8 mol·m−2·s−1·Pa−1 and H2 /N2 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, H2, Ne, CO2, N2, and CH4) was determined by fitting the gas permeance temperature dependence to one of three models: solid state, gas-translational, or surface diffusion.
AB - 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◦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 H2 permeances at 600◦C for the TMOS-, MTMOS-, and DMDMOS-derived membranes were respectively 1.7 × 10−7, 2.4 × 10−7, and 4.4 × 10−8 mol·m−2·s−1·Pa−1 and H2 /N2 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, H2, Ne, CO2, N2, and CH4) was determined by fitting the gas permeance temperature dependence to one of three models: solid state, gas-translational, or surface diffusion.
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U2 - 10.3390/membranes9110144
DO - 10.3390/membranes9110144
M3 - Article
AN - SCOPUS:85074669534
SN - 2077-0375
VL - 9
JO - Membranes
JF - Membranes
IS - 11
M1 - 144
ER -