Details
| Original language | English |
|---|---|
| Pages (from-to) | 284-291 |
| Number of pages | 8 |
| Journal | Journal of membrane science |
| Volume | 469 |
| Early online date | 30 Jun 2014 |
| Publication status | Published - 1 Nov 2014 |
Abstract
Pressed graphite was evaluated as a potential membrane for steam reforming of ethanol in membrane reactors. In ethanol steam reforming, hydrogen has to be in situ removed selectively from a mixture with ethanol, CO2, and H2O. Commercial graphite flakes (single crystals) have been pressed into disc membranes of different thicknesses. Both single gas permeation and H2/CO2/H2O mixed gas permeation were studied. From single gas permeation, a relatively high ideal separation factor of 35,. . .,60 for the H2/CO2 mixture could be predicted. However, the study of the real separation factor of this mixture by gas-chromatographic analysis gave real mixture separation factors around 5. This experimental finding is explained by a Knudsen-type mechanism with permeation paths along the grain boundaries of the pressed graphite flakes. At temperatures between 100 and 250°C, the pressed graphite membrane is indeed hydrogen-selective. Hydrogen is separated from a H2/CO2/H2O mixture with a separation factor of 5 relative to CO2 and 12 relative to H2O, but only 2.4 relative to ethanol. Pressing of the graphite crystals results in a self-orientation (brick layer structure) of the individual graphite crystals. Hydrogen permeation parallel to the aligned flake-shaped crystals is by the factor 25 faster than perpendicular to them. The hydrogen permeabilities through the pressed graphite membranes are about one to two orders of magnitude higher than those through molecular sieve membranes such as supported zeolite or MOF membranes.
Keywords
- Gas separation, Graphite membrane, Hydrogen separation, Membrane supported ethanol steam reforming
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Biochemistry
- Materials Science(all)
- Chemistry(all)
- Physical and Theoretical Chemistry
- Chemical Engineering(all)
- Filtration and Separation
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In: Journal of membrane science, Vol. 469, 01.11.2014, p. 284-291.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Pressed graphite crystals as gas separation membrane for steam reforming of ethanol
AU - Schulz, A.
AU - Steinbach, F.
AU - Caro, J.
PY - 2014/11/1
Y1 - 2014/11/1
N2 - Pressed graphite was evaluated as a potential membrane for steam reforming of ethanol in membrane reactors. In ethanol steam reforming, hydrogen has to be in situ removed selectively from a mixture with ethanol, CO2, and H2O. Commercial graphite flakes (single crystals) have been pressed into disc membranes of different thicknesses. Both single gas permeation and H2/CO2/H2O mixed gas permeation were studied. From single gas permeation, a relatively high ideal separation factor of 35,. . .,60 for the H2/CO2 mixture could be predicted. However, the study of the real separation factor of this mixture by gas-chromatographic analysis gave real mixture separation factors around 5. This experimental finding is explained by a Knudsen-type mechanism with permeation paths along the grain boundaries of the pressed graphite flakes. At temperatures between 100 and 250°C, the pressed graphite membrane is indeed hydrogen-selective. Hydrogen is separated from a H2/CO2/H2O mixture with a separation factor of 5 relative to CO2 and 12 relative to H2O, but only 2.4 relative to ethanol. Pressing of the graphite crystals results in a self-orientation (brick layer structure) of the individual graphite crystals. Hydrogen permeation parallel to the aligned flake-shaped crystals is by the factor 25 faster than perpendicular to them. The hydrogen permeabilities through the pressed graphite membranes are about one to two orders of magnitude higher than those through molecular sieve membranes such as supported zeolite or MOF membranes.
AB - Pressed graphite was evaluated as a potential membrane for steam reforming of ethanol in membrane reactors. In ethanol steam reforming, hydrogen has to be in situ removed selectively from a mixture with ethanol, CO2, and H2O. Commercial graphite flakes (single crystals) have been pressed into disc membranes of different thicknesses. Both single gas permeation and H2/CO2/H2O mixed gas permeation were studied. From single gas permeation, a relatively high ideal separation factor of 35,. . .,60 for the H2/CO2 mixture could be predicted. However, the study of the real separation factor of this mixture by gas-chromatographic analysis gave real mixture separation factors around 5. This experimental finding is explained by a Knudsen-type mechanism with permeation paths along the grain boundaries of the pressed graphite flakes. At temperatures between 100 and 250°C, the pressed graphite membrane is indeed hydrogen-selective. Hydrogen is separated from a H2/CO2/H2O mixture with a separation factor of 5 relative to CO2 and 12 relative to H2O, but only 2.4 relative to ethanol. Pressing of the graphite crystals results in a self-orientation (brick layer structure) of the individual graphite crystals. Hydrogen permeation parallel to the aligned flake-shaped crystals is by the factor 25 faster than perpendicular to them. The hydrogen permeabilities through the pressed graphite membranes are about one to two orders of magnitude higher than those through molecular sieve membranes such as supported zeolite or MOF membranes.
KW - Gas separation
KW - Graphite membrane
KW - Hydrogen separation
KW - Membrane supported ethanol steam reforming
UR - http://www.scopus.com/inward/record.url?scp=84904465765&partnerID=8YFLogxK
U2 - 10.1016/j.memsci.2014.06.047
DO - 10.1016/j.memsci.2014.06.047
M3 - Article
AN - SCOPUS:84904465765
VL - 469
SP - 284
EP - 291
JO - Journal of membrane science
JF - Journal of membrane science
SN - 0376-7388
ER -