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

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4 Results and discussion The average crystal size is calculated from XRD diffraction pattern using the Scherrer’s equation at the peak at ~30º. The average crystal sizes of the 8YSZ powders are listed in Table 22. The average crystal size increases from 5.7 to 7.0 nm for the 8YSZ powders that were calcined at 500ºC when the SDA F127 was added to the 8YSZ sol that contained the combination of acetyl acetone and caproic acid. The larger particle might have been formed due to the structuring effect of the long polymeric chains of F127. This effect seems to be enhanced when the combination of acetyl acetone and caproic acid is not present, and result in an increase of average crystal size from 7.0 to 8.5 nm. This might be explained by the absence of the hindering of crystal growth due to the capping effect of the acetyl acetone or caproic acid groups. The pristine polymeric 8YSZ sols maintain their fluorite structure at any tested temperature with increasing crystal size from 5.5, 7.0, 13.5 to 72 nm at respectively, 500, 600, 800 and 1080ºC (Figure 47). The increase of average crystal size is likely attributed to the sintering behaviour of the nano-crystalline particles. Intensity (a.u.) 20 30 40 50 60 70 2 Theta [º] Figure 47 XRD diffraction patterns of dried 8YSZ sols calcined at 500-1080ºC with 2h dwell time (heating and cooling ramps 2 K/min). The inlay presents the crystal size as a function of the calcination temperature. The XRD data suggest the formation of cubic 8YSZ material at temperature below 500ºC (Figure 47) and even below 450ºC (Figure 46). All the calcined 8YSZ powders listed in Table 22 present the cubic phase. So the cubic phase formation is independent on the organic additives. Likely, the cubic phase formation is determined by the 8YSZ sol properties. 79 Crystal size [nm] 80 60 40 20 0 500 600 700 800 900 1000 1100 T [ºC] 1080ºC 800ºC 600ºC 500ºC
4 Results and discussion DTA/TG analyses were performed to determine the crystallisation temperatures and the temperature where the organics are removed. The organics can be the propoxide groups attached to the zirconium precursor, nitrate-groups from the yttrium precursor, bonded 2-propanol groups, caproic acid, acetyl acetone and the structure directing agents. Figure 48-A shows the DTA curves from the powders that were prepared from 8YSZ sols, 8YSZ sols with the SDA 127 and the 8YSZ sols with the SDA 127 plus the combination acetyl acetone and caproic acid. Figure 48-A presents the DTA curve of 8YSZ powder and shows a broad exothermic peak between 150 and 400ºC. Approximately 55 wt% is lost in this temperature range from the 8YSZ powder when the TG curve is considered (Figure 48-B). This can be assigned to the gradual burn out of the (bonded) n-propanol, nitrate and propoxide groups. Exothermic peaks are observed at approximately 160, 200, 270 and 360ºC. Further analysis with e.g. DTA in combination with a mass spectrometer is required to indentify these exothermic peaks. Clearly, no crystallisation temperature can be extracted from this data. 8YSZ powders with F127 added to the sol show a less complex DTA curve. Less weight loss is observed as a result of drying at 140 ºC for 8 hours instead of standard 4 hours. The dehydration of the 8YSZ powder that contains F127 is observed at 100ºC by show an endothermic peak. The exothermic peak at 435ºC can not be assigned to the crystallisation temperature due to the fact that the material is show cubic phase formation at 400ºC (results not shown). Therefore, both exothermic peaks at 235 and 435ºC are likely related to the burnout of the organic species mentioned for the 8YSZ in combination with the combustion of the F127. F127 seem to organise the gradual burn out of the organic species when the 8YSZ powder and 8YSZ powder with F127 are compared. This effect is no longer visible when the combination acetyl acetone and caproic acid are added to the sol. Again, a broad exothermic peak between 175 and 410ºC with a weight loss of 35% is observed. One is unable to distinguish the crystallisation temperature and the temperature when each of the organic compounds is combusted. The combination of acetyl acetone and caproic acid seem to be bonded to the inorganic solids in a broad temperature range. 80
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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 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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Page 42 and 43: 2 Theoretical background 2.4 Microp
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Page 46 and 47: 2 Theoretical background wall inter
Page 48 and 49: 3 Experimental 3 Experimental The m
Page 50 and 51: 3 Experimental vacuum sample holder
Page 52 and 53: 3 Experimental o of as-made DOH cry
Page 54 and 55: 3 Experimental Another solution was
Page 56 and 57: 3 Experimental 3.4 Characterisation
Page 58 and 59: 3 Experimental Element analysis The
Page 60 and 61: 3 Experimental Additionally, the hy
Page 62 and 63: 4 Results and discussion Abundance
Page 64 and 65: 4 Results and discussion 4.2 Zeolit
Page 66 and 67: 4 Results and discussion Table 14 D
Page 68 and 69: 4 Results and discussion hours usin
Page 70 and 71: 4 Results and discussion Intensity
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 88 and 89: 4 Results and discussion V [cm ads
Page 92 and 93: 4 Results and discussion DTA µV/mg
Page 94 and 95: 4 Results and discussion Vads / cm
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 120 and 121: 4 Results and discussion He Permean
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Page 124 and 125: 5 Conclusions and recommendations m
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
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Page 137: Band | Volume 8 ISBN 978-3-89336-52
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