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Water/hydrogen/hexa...
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Rezai, Seyed Alireza SadatCatalysis Research Centre, University of Cape Town
(author)
Water/hydrogen/hexane multicomponent selectivity of thin MFI membranes with different Si/Al ratios
- Article/chapterEnglish2008
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Elsevier BV,2008
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printrdacarrier
Numbers
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LIBRIS-ID:oai:DiVA.org:ltu-6240
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https://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-6240URI
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https://doi.org/10.1016/j.micromeso.2007.04.002DOI
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Language:English
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Summary in:English
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Subject category:ref swepub-contenttype
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Subject category:art swepub-publicationtype
Notes
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Validerad; 2008; 20071211 (linste)
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MFI films with a thickness of about 550 nm were prepared on α-alumina substrates. The surface Si/Al ratios (XPS) were 157 and 62 for silicalite-1 and ZSM-5 films, respectively, and in accordance, XRD data indicated lower ratios for ZSM-5 films. Higher ratios were observed by ICP-AES for crystals grown in the bulk of the synthesis mixtures. Six membranes of each type were prepared. Porosimetry measurements showed that all membranes were of high and similar quality. Single gas permeances for H2, N2, He, CO2 and SF6 at 25 °C were very similar within each type of membranes. However, the average hydrogen permeance was 27% lower and the average H2/SF6 single gas permeance ratio was 67% higher for ZSM-5 membranes. These differences are attributed to a narrower effective pore diameter for the ZSM-5 membranes due to the sodium counter ions. Separation of mixtures of H2O, H2 and n-hexane (helium balance) was investigated in the temperature range 25-350 °C. The highest separation factors α-H2O/H2 were observed at 25 °C and were 14.3 and 19.7 for silicalite-1 and ZSM-5, respectively. The membranes were selective also at 100 °C and the separation factors were about 3.2 and 6 for silicalite-1 and ZSM-5, respectively. However, the selectivity decreased at elevated temperatures and the separation factor approached 1 at temperatures above 180 °C for both membrane types. The observed water selectivity was attributed to weak adsorption of water on polar sites. A low (1.5-3) α-H2O/n-C6 separation factor was observed for both membrane types for the entire investigated temperature range.
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Lindmark, Jonas
(author)
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Andersson, Charlotte
(author)
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Jareman, Fredrik
(author)
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Möller, KlausCatalysis Research Group, University of Cape Town
(author)
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Hedlund, JonasLuleå tekniska universitet,Industriell miljö- och processteknik(Swepub:ltu)johe
(author)
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Catalysis Research Centre, University of Cape TownCatalysis Research Group, University of Cape Town
(creator_code:org_t)
Related titles
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In:Microporous and Mesoporous Materials: Elsevier BV108:1-3, s. 136-1421387-18111873-3093
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