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

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4 Results and discussion 4.2 Zeolite materials and layers All silica clathrasil 8-ring deca-dodecasil 3R (DDR) zeolite type might be a potential membrane material to separate CO2 from other gasses. 6-ring dodecasil 1H (DOH), also an all silica clathrasil, could be an interesting membrane material for H2 to CO2 separation. First, DDR syntheses results will be described briefly. Second, the successful syntheses of DOH will be described including the results to obtain quasi SDA-free DOH structures, followed by a discussion on the formation of secondary grown DOH layers on α-Al2O3 supports. 4.2.1 Deca-dodecasil-3R synthesis Deca-dodecasil-3R (DDR) is not commercially available but can be synthesised from silicon precursors which are hydrolysed in the presence of the structure directing agents (SDA) at high pH. These reactions are performed in Teflon lined steel autoclaves at high temperatures for several days. Aminoadamantane (ADA) is the most frequently used known SDA for the formation of DDR. Dodecasil-1H is one of the competing phases of DDR using the same gel composition. 60 DOH is synthesised at temperatures above 190ºC while DDR requires synthesising temperatures in the range of 160-170ºC. Table 12 presents the obtained phases as a function of the synthesis temperature. It shows shown that DOH is synthesised at higher temperatures. Changing the gel composition did not result in single phase DDR zeolite material. Different polymorphs of DOH, SGT and DDR (SGT is zeolite type Sigma 2) are formed at temperatures below 200ºC, as seen in Figure 26 A and B. A) Polymorphs Figure 26 A) Optical microscope image of polymorph products obtained at 170ºC for 25 days. B) DOH- DDR polymorphs found by den Exter et al. 67 . 53 B)
4 Results and discussion Table 12 DDR synthesis conditions presenting the molar ratio and crystallisation time in days SiO2:ADA:EN:H2O Crystallisation conditions Obtained phase Days Temp. ºC 100:30.7:266:7300 60 160 DDR/SGT 100:30.7:266:7300 25 170 DDR/SGT/DOH 100:11:267:7405 27 200 DOH The Sigma 2 (SGT) zeolite type coexists in the products synthesised at temperatures below 200ºC. SGT can be synthesised in the presence of sodium and aluminium as well. Inductively Coupled Plasma with Optical Emission Spectroscopy found traces of these compounds. These impurities might act as structure directing agents. SGT in the products could not be excluded by changing the gel composition (Table 13). Single phase DDR synthesis seems to be complex. Only a few groups are able to prepare pure DDR 65,125 who used a well studied synthesis conditions and raw materials. Table 13 DDR synthesis conditions presenting the molar ratio of the gel composition and crystallisation time in days synthesised at 160ºC SiO2:ADA:EN:H2O Crystallisation conditions in days Obtained phase 100:11:267:7405 28 DDR/SGT 100:30.7:266:7300 60 DDR/SGT 100:47:266:3600 33 DDR/SGT/DOH 100:47:404:6800 25 DDR/SGT/DOH 4.2.2 Structure directing agent free Dodecasil-1H synthesis 4.2.2.1 Synthesis of small DOH nuclei Dodecasil 1H (DOH) can be synthesised successfully using ammonia and ethylenediamine as the base. The zeolite type SGT (Sigma 2) or a mixture of DOH and deca-dodecasil 3R (DDR) instead of single phase DOH crystals was obtained when using the gel composition as reported by Den Exter. 66 Pure DOH was obtained using a gel composition with less ADA and EN (Table 14). Pure DOH was synthesised with a 9-18 Si/ADA mol ratio. Decreasing the water content in the gel may reduce the hydrolysis rate and thereby result in smaller crystals. Partial crystalline DOH product was obtained when the mol ratio of H2O/Si was reduced from 74 to 10, most likely due to inhomogeneous components in the gel (Table 15). 54
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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............
Page 14 and 15: 1 Introduction and aims 1 Introduct
Page 16 and 17: 1 Introduction and aims Candidate m
Page 18 and 19: 2 Theoretical background 2 Theoreti
Page 20 and 21: 2 Theoretical background Despite th
Page 22 and 23: 2 Theoretical background Table 2 Ox
Page 24 and 25: 2 Theoretical background 2.1.2 Micr
Page 26 and 27: 2 Theoretical background Poly-cryst
Page 28 and 29: 2 Theoretical background membranes
Page 30 and 31: 2 Theoretical background Dry or wet
Page 32 and 33: 2 Theoretical background the materi
Page 34 and 35: 2 Theoretical background Figure 9 D
Page 36 and 37: 2 Theoretical background Figure 11
Page 38 and 39: 2 Theoretical background due to its
Page 40 and 41: 2 Theoretical background 2.3.3.2 Mi
Page 42 and 43: 2 Theoretical background 2.4 Microp
Page 44 and 45: 2 Theoretical background Figure 15
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 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
Page 74 and 75: 4 Results and discussion DOH crysta
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Page 78 and 79: 4 Results and discussion characteri
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Page 82 and 83: 4 Results and discussion 4.3.1.1 Ke
Page 84 and 85: 4 Results and discussion Solid Cont
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Page 88 and 89: 4 Results and discussion V [cm ads
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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
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4 Results and discussion Tungsten 5
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4 Results and discussion Mol% Carbo
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4 Results and discussion Permeance
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4 Results and discussion He Permean
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5 Conclusions and recommendations m
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5 Conclusions and recommendations m
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6 References 22. Shao, Z., Dong, H.
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6 References 65. Van den Berg, A. W
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6 References 108. Wen, T. L., Heber
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Curriculum Vitae - George van der D
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Last but not least, I would like to
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Band | Volume 8 ISBN 978-3-89336-52
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