Gas permeation redox effect on binary lanthanum cobalt silica membranes with enhanced silicate formation

Ballinger, Benjamin, Motuzas, Julius, Smart, Simon and Diniz da Costa, Joao C. (2015) Gas permeation redox effect on binary lanthanum cobalt silica membranes with enhanced silicate formation. Journal of Membrane Science, 489 220-226. doi:10.1016/j.memsci.2015.04.025

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Author Ballinger, Benjamin
Motuzas, Julius
Smart, Simon
Diniz da Costa, Joao C.
Title Gas permeation redox effect on binary lanthanum cobalt silica membranes with enhanced silicate formation
Journal name Journal of Membrane Science   Check publisher's open access policy
ISSN 1873-3123
0376-7388
Publication date 2015-09-01
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.memsci.2015.04.025
Open Access Status File (Author Post-print)
Volume 489
Start page 220
End page 226
Total pages 7
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2016
Language eng
Formatted abstract
This work investigates the characterisation and performance of binary lanthanum cobalt doped silica membranes. The prepared membranes resulted in temperature dependent gas transport, a characteristic of molecular sieving membranes. Under reduction and oxidation cycles at 500 °C, the maximum steady state permeance of the membranes reached 1.5×10−7 mol m−2 s−1 Pa−1 at 500 °C. It was found that the membranes contained both cobalt oxide and lanthanum silicate phases embedded in the silica matrix. The permeance of all tested gases under redox cycling decreased during the 350 h permeation test, though the reduction was slightly more pronounced for larger gas molecules (H2, CO2 and N2). As a result, He/CO2 permselectivity increased from ~80 at the initial tests to 196 during the redox cycling test, an improvement of 145%. This indicates that the pore sizes ≥2.89 Å (i.e. kinetic diameter of H2) preferentially collapsed/closed instead of the smaller pores available for the permeation of the smaller gas He (dk=2.6 Å). These results are contrary to other silica and metal doped silica membranes which undergo thermal densification and closure of the smaller pore sizes. Therefore, the formation of lanthanum silicates conferred superior structural stability in the silica matrix.
Keyword Silica membranes
Cobalt oxide
Lanthanum silicate
Gas separation
Redox
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2016 Collection
 
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Citation counts: TR Web of Science Citation Count  Cited 6 times in Thomson Reuters Web of Science Article | Citations
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