Inorganic Microporous Membranes for Gas Separation in Fossil Fuel ...

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4 Results and discussion Permeance (10 -9 mol/s m2Pa) Permeance (10 -9 mol/s m 2 Pa) 1.E-06 10 -6 1.E-07 10 -7 1.E-08 10 -8 1.E-09 10 -9 1.E-10 1E-08 10 -10 10 -8 10 -9 1E-09 10 -10 107 #204; 600ºC #205; 600ºC 1E-10 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Kinetic diameter (nm) #143; 500ºC #132; 500ºC #202; 500ºC Figure 74: Permeability (measured at 200ºC) of Ti0.5Zr0.5O2 membranes calcined at 500 and 600ºC for different gasses as a function of their kinetic diameter. The lines serve only as a guide to the eye. In Figure 74 the measured permeances of a series of gasses with kinetic diameters ranging from 0.26 to 0.55 nm are presented for all membranes calcined at 500 and 600ºC. All membranes, demonstrate a significant increase in permeability for gasses with a kinetic diameter below 0.3 nm. These data are indicative of the existence of pores in the Ti0.5Zr0.5O2 layers having dimensions which make them primarily accessible to relatively small molecules such as He and H2. This is especially manifest in membrane #205, which achieves a measured permselectivity for He/H2 and He/N2 of 2.0 and 14, respectively. In Figure 75 the effect of temperature on H2 and CO2 permeation are presented for membrane #205 in Arrhenius-type plots. The linearity of the relation between logarithm of permeance and reciprocal temperature confirms a thermally activated transport mechanism. The activation energy Ea can have any sign; in this study the sign is positive when the permeation increases with temperature. The measured activation energy for H2 and CO2 transport amount to 8.4 and 4.9 kJ/mol, respectively. As a result of these
4 Results and discussion differences the H2/CO2 permselectivity of this membrane increases from 4.2 to 5.3 as the temperature increases from 115 to 190ºC. This is comparable to values observed for ZrO2 membranes. 141,142 The activation energies for He transport through membranes #202, #204 and #205 are 3.9, 7.9 and 15 kJ/mol, respectively, which is indicative of an increasing degree of micropore diffusion in these membranes. Ln[Permeance s m 2 Pa/mol)] 0.24 228 0.25 0.26 189 0.27 0.28 156 0.29 0.30 103 0.31 103 0.32 -12.0 7 -12.5 -13.0 -13.5 -14.0 T (ºC) -14.5 3 0.24 0.25 0.26 0.27 0.28 0.29 0.30 0.31 0.32 1000/RT (mol/kJ) 108 Hydrogen Carbon dioxide Permselectivity Figure 75: H2/CO2 permselectivity as a function of temperature and Arrhenius plots for H2 and CO2 permeation of a Ti0.5Zr0.5O2 membrane (#205) calcined at 600ºC. Because of its outstanding performance, the hydrothermal stability of this particular membrane (#205) has been tested. The effect of exposure to water vapour on He and N2 permeation is presented in Figure 76. During the exposure, a strong decrease in both the He and N2 permeance is immediately observed. The amount of permeating water was too small to be determined gravimetrically. After termination of the steam exposure, degassing results in a steady increase of both He and N2 permeation. Only after a period of approximately 750 hours the He permeation starts to decrease. Both permeation measurements and visual inspection of the membrane surface after the experiment exclude the occurrence of layer delamination which can result from hydrothermal treatment. In fact, a He/N2 permselectivity above 10 is observed again after exposure to steam after flushing the membrane for 500 h which demonstrates a high degree of stability of the micropore structure. Besides, the γ-Al2O3 intermediate layer was not delaminated as expected from the hydrothermal testing on SiO2 membranes of the recently reported work of Duke et al. 94 6 5 4 H 2/CO 2 Permselectivty
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Mitglied der Helmholtz-Gemeinschaft
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Forschungszentrum Jülich GmbH Inst
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List of Abbreviations Ac Acetyl Ace
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Summary CO2 capture and storage mig
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Zusammenfassung Die Abtrennung und
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Content Content CONTENT............
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1 Introduction and aims 1 Introduct
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1 Introduction and aims Candidate m
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2 Theoretical background 2 Theoreti
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2 Theoretical background Despite th
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2 Theoretical background Table 2 Ox
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2 Theoretical background 2.1.2 Micr
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2 Theoretical background Poly-cryst
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2 Theoretical background membranes
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2 Theoretical background Dry or wet
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2 Theoretical background the materi
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2 Theoretical background Figure 9 D
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2 Theoretical background Figure 11
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2 Theoretical background due to its
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2 Theoretical background 2.3.3.2 Mi
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2 Theoretical background 2.4 Microp
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2 Theoretical background Figure 15
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2 Theoretical background wall inter
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3 Experimental 3 Experimental The m
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3 Experimental vacuum sample holder
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3 Experimental o of as-made DOH cry
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3 Experimental Another solution was
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3 Experimental 3.4 Characterisation
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3 Experimental Element analysis The
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3 Experimental Additionally, the hy
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4 Results and discussion Abundance
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4 Results and discussion 4.2 Zeolit
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4 Results and discussion Table 14 D
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Page 72 and 73: 4 Results and discussion The carbon
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Page 76 and 77: 4 Results and discussion 900 [ºC]
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Page 90 and 91: 4 Results and discussion The averag
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Page 96 and 97: 4 Results and discussion The increa
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Page 100 and 101: 4 Results and discussion V micro /V
Page 102 and 103: 4 Results and discussion In pure Ti
Page 104 and 105: 4 Results and discussion In summary
Page 106 and 107: 4 Results and discussion Intensity
Page 108 and 109: 4 Results and discussion nanonic YS
Page 110 and 111: 4 Results and discussion ~50nm TiO2
Page 112 and 113: 4 Results and discussion Raman Inte
Page 114 and 115: 4 Results and discussion Tungsten 5
Page 116 and 117: 4 Results and discussion Mol% Carbo
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Page 126 and 127: 6 References 22. Shao, Z., Dong, H.
Page 128 and 129: 6 References 65. Van den Berg, A. W
Page 130 and 131: 6 References 108. Wen, T. L., Heber
Page 132 and 133: Curriculum Vitae - George van der D
Page 134: Last but not least, I would like to
Page 137: Band | Volume 8 ISBN 978-3-89336-52
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