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

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4 Results and discussion The increase in pore size in combination with a decrease of the relative microporous adsorbed volume Vmicro/Vtotal (56-6%) with increasing temperature is in agreement with the results found by Xu et al. 112 The pore size increase seems to be coupled with the increase in crystal size, which increases from 6.1 at 400ºC to 19 nm at 600ºC (Figure 54). Similar trend have been observer for the TiO2 powders. Table 24 Microstructure properties of dried ZrO2 sols Calcination Temp. in [ºC] Crystal size nm SBET m 2 /g Vtotal cm 3 /g Vmicro cm 3 /g SF nm BJH nm 140 amorphous - - - - 400 6.1 74 0.034 0.019 1.5 - 500 8.3 77 0.054 0.019 2.2 - 600 19 6 0.011 0.001 4.0 Vads / cm 3 g -1 60 50 40 30 20 10 500ºC 400ºC 600ºC 85 ZrO 2 0,0 0,2 0,4 0,6 0,8 1,0 p/p0 0 Figure 52 N2 isotherms ZrO2 calcined at 400ºC (◊), 500ºC (○) and 600ºC (□). Open symbols present the adsorption and closed symbols the desorption points. The dried ZrO2 sols crystallize to tetragonal ZrO2 in the temperature range of 140-400ºC. The TG plot (Figure 53) of dried ZrO2 can be subdivided into three steps. The first step presents the water and loosely bounded organic removal in the temperature range of 50 to 300ºC. A sharp weight loss is obtained in the second step up to 400ºC where the amine groups leave the inorganic-organic material in combination with crystallisation. No
4 Results and discussion significant weight loss is observed in the third step where the remaining organics are combusted. The carbon content measurements at 140 to 600ºC are complementary to these results (Figure 72). Exo uV/mg 0,3 0,2 0,1 0,0 -0,1 -0,2 -0,3 100 200 300 400 500 600 700 0 800 Temperature [ºC] 86 DTA TG Figure 53 DTA-TG curves of dried ZrO2 sol. The DTA results (Figure 53) are complementary to the TG results. The exothermic peak in the DTA plot at 308ºC suggests the removal of organic residues (Figure 53). More organics remain in the ZrO2 microporous material in the temperature range of 140-600ºC compared to TiO2 (Figure 72). The second exothermic peak at 358ºC might be related to the formation of tetragonal ZrO2. A combination of tetragonal and monoclinic ZrO2 (tetra/mono >>1) is formed when the dried ZrO2 sol is calcined at 600ºC (Figure 54). No cubic ZrO2 could be observed as expected from the mild temperature conditions and absence of a cubic phase stabilisator such as Y2O3. Raman spectroscopy did observe only monoclinic and tetragonal ZrO2 on the ZrO2 layers and will be discussed in the next section. The phase transformation from tetragonal to monoclinic ZrO2 may form gradually in the temperature range of 450- 650ºC. The gas physisorption, DTA and XRD results on ZrO2 DEA 2 wt% sols that are dried and calcined at 140, 400, and 500ºC for 3 hours with a heating rate of 25ºC/hours suggest that these materials might form microporous membranes with rather low permeability due to the small specific surface areas. 120 100 80 60 40 20 weight loss %
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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 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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Page 56 and 57: 3 Experimental 3.4 Characterisation
Page 58 and 59: 3 Experimental Element analysis The
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Page 62 and 63: 4 Results and discussion Abundance
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Page 72 and 73: 4 Results and discussion The carbon
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Page 94 and 95: 4 Results and discussion Vads / cm
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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
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Page 126 and 127: 6 References 22. Shao, Z., Dong, H.
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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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