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Characterization of Co‐Doped Silica for Improved Hydrothermal Stability and Application to Hydrogen Separation Membranes at High Temperatures
Author(s) -
Igi Ryosuke,
Yoshioka Tomohisa,
Ikuhara Yumi H.,
Iwamoto Yuji,
Tsuru Toshinori
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02563.x
Subject(s) - permeance , microporous material , materials science , hydrogen , hydrothermal circulation , chemical engineering , membrane , hydrothermal synthesis , doping , partial pressure , analytical chemistry (journal) , permeation , nuclear chemistry , chemistry , chromatography , oxygen , organic chemistry , composite material , biochemistry , optoelectronics , engineering
Co‐doped silica sol solutions with varying Co composition (Co/(Si+Co)=10–50 mol%) were prepared from tetraethoxysilane and Co(NO 3 ) 2 ·6H 2 O. Subsequently, these solutions were used in the preparation of hydrogen separation microporous membranes with enhanced hydrothermal stability at 500°C under a steam pressure of 300 kPa. At Co concentrations >33%, the XRD pattern and peak intensity of the Co‐doped silica preparations were similar and were not dependent on Co composition, suggesting that Co was incorporated into the silica network. The best H 2 permeation performance in a steam atmosphere (500°C; steam pressure, 300 kPa) was obtained using silica doped with approximately 30 mol% Co. Co‐doped silica membranes (Co 33 mol%) fired at 600°C under a steam partial pressure of 90 kPa showed stable gaseous permeances and a H 2 permeance of approximately 2.00–4.00 × 10 −6 m 3 (STP)·(m·s·kPa) −1 with a selectivity of 250–730 (H 2 /N 2 ), even after 60 h of exposure to steam (steam pressure, 300 kPa) at 500°C.