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Water/hydrogen/hexa...
Water/hydrogen/hexane multicomponent selectivity of thin MFI membranes with different Si/Al ratios
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- Rezai, Seyed Alireza Sadat (författare)
- Catalysis Research Centre, University of Cape Town
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Lindmark, Jonas (författare)
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Andersson, Charlotte (författare)
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Jareman, Fredrik (författare)
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- Möller, Klaus (författare)
- Catalysis Research Group, University of Cape Town
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- Hedlund, Jonas (författare)
- Luleå tekniska universitet,Industriell miljö- och processteknik
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(creator_code:org_t)
- Elsevier BV, 2008
- 2008
- Engelska.
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 108:1-3, s. 136-142
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- 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.
Ämnesord
- TEKNIK OCH TEKNOLOGIER -- Kemiteknik -- Kemiska processer (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Chemical Engineering -- Chemical Process Engineering (hsv//eng)
Nyckelord
- Chemical Technology
- Kemisk teknologi
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