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

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3 Experimental 3 Experimental The material synthesis and layer preparation methods are outlined in this chapter. First, the support and the supporting membrane layer formation are discussed. Next, the preparation of zeolite materials, post treatments and zeolite layer formations are described. In section 3.3 the sol-gel synthesis and the coating steps are outlined. The last section includes the characterisation techniques used to study the bulk material and the microporous membranes. 3.1 Supports and intermediate layers 3.1.1 Support formation Macroporous supports are the basis of graded porous membranes. Macroporous α-Al2O3 discs were prepared by colloidal filtration of ultra pure alumina powder (AKP30 Sumitomo Chemical Co., Tokyo, Japan) in HNO3. Alumina powder was mixed with equal amounts of grams of 0.02 M HNO3 by ultrasonic vibration for 14 min at 200 Watt (Model 450 Sonifier, Branson Ultrasonics Corp., Danbury, CT). This suspension was sieved with a 200 µm metal filter. Next, the mixture was filtrated by a Schleicher & Schuell 800 nm membrane sieve using a vacuum pump for 3 to 5 hours. After drying overnight, a ‘green’ substrate was obtained (Figure 16). AKP30 Suspension HNO 3 Sinter oven 1100ºC 1100ºC 2h +2ºC/min powder mixture Ultrasonic Grind in 36Øx2.4d in mm 37 Polish filter Vacuum filitration filitration Vacuum >3h Drying > 12h 12h Figure 16 Schematic drawing of support formation by means of vacuum filtration
3 Experimental Finally, the substrates were sintered at 1100°C for 2 hours with a heating and cooling rate of 2°C/min. Fired substrates were then grinded into dimensions of 36 mm Ø and 2.0-2.4 mm thickness. The surface roughness was decreased by polishing to avoid pinhole in the membrane layers. First, the α-Al2O3 supports were roughly polished with a 74 µm diamond in a metal polishing plate (Ecomet 4 Buehler, Germany) with a pressure of 12.5- 25 kPa for 15 minutes. This step was repeated with a 30 µm diamond in a paraffin plate with identical pressure and duration. The polished supports were ultrasonically cleaned in ethanol and fired at 800ºC for 2 hours with a heating and cooling ramp of 2ºC/min. This resulted in a vague mirror like disc with a thickness in the range of 1.90-2.35 mm. 3.1.2 Intermediate layer material characterisation and layer formation 0.5 M Boehmite sols were coated on the supports under clean-room conditions. Boehmite sols were prepared by reacting 0.5 mol of aluminum-tri-sec-butoxide (ATSB; 97% purity, Aldrich) with 70 mol H2O at >90ºC. The ATSB was added drop wise under argon-gas flow to avoid premature hydrolysis. The temperature of the reaction mixture was kept >80°C to avoid the formation of bayerite (Al(OH)3). After the ATSB was added, the mixture was kept at 90°C for 1 h to evaporate the formed butanol. The mixture was subsequently cooled to 60°C. The acidity was adjusted with 1 M HNO3 (E. Merck, Darmstadt, Germany) to a pH of 2.8 to break down and prevent agglomeration. 5 During the synthesis, the sol was stirred vigorously. The peptized mixture was refluxed for 20 h at 90°C, resulting in a 0.5 M Boehmite sol with a clear white/blue appearance. These sols remained stable for several weeks. The Boehmite sol coating in clean-room conditions was performed by dip or spin coating. The dip coating procedures were similar as those reported by Nijmeijer et al. A dipcoating solution of 0.5 M Boehmite sol and 3 wt% poly(vinyl-alcohol) (hereafter referred as PVA, Aldrich) in 0.05 M HNO3 with a 2/3 volume ratio was stirred carefully to prevent air bubbles. PVA acted as a drying chemical controlling additive and was dissolved in 0.05 M HNO3 to avoid agglomeration of the Boehmite particles in the Boehmite sol/PVA mixture. Both solutions were filtered with 800 nm filters (Model FP030/50, Green Rim, Schleicher and Schuell GmbH, Dassel, Germany) to avoid large agglomerates. The polished and cleaned surface of α-Al2O3 supports were coated by bringing it in contact with the Boehmite sol for a certain time, using an automated dedicated dipcoating apparatus that includes electronic height adjustment (Nima technologies UK) under clean-room conditions, see Figure 17. The fixation of the support was performed by mechanical clips or by a vacuum positioning system. Spin coating procedures are performed similarly. An excessive amount of Boehmite sol was applied on the polished surface of α-Al2O3 supports, which is fixed by an integrated 38
Page 1 and 2: Mitglied der Helmholtz-Gemeinschaft
Page 4 and 5: Forschungszentrum Jülich GmbH Inst
Page 6 and 7: List of Abbreviations Ac Acetyl Ace
Page 8 and 9: Summary CO2 capture and storage mig
Page 10 and 11: Zusammenfassung Die Abtrennung und
Page 12 and 13: 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
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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
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Page 56 and 57: 3 Experimental 3.4 Characterisation
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4 Results and discussion 20 30 40 5
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4 Results and discussion V micro /V
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4 Results and discussion In pure Ti
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4 Results and discussion In summary
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4 Results and discussion Intensity
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4 Results and discussion nanonic YS
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4 Results and discussion ~50nm TiO2
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4 Results and discussion Raman Inte
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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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