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

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1 Introduction and aims Candidate materials include polymer (organic) membranes as well as ceramic (inorganic) membrane systems with tailored properties and operational characteristics. 2. Precombustion capture Gasification processes of fossil fuel with a subsequent CO-shift reaction offer high potential for CO2-removal. The CO-shift reaction results in the formation of CO2 and H2 (180-550ºC 1 ). If H2 can be continuously removed from the gas mixture, CO2 can easily be separated and stored. H2 can be used for generating electricity in gas turbines and fuel cells, and for the production of chemicals and synthetic fuels based on fossils and biomass. Physical absorption for H2/CO2 separation (net efficiency losses approx. 10 % points) will be the major competing technology for molecular sieving (porous ceramic membranes) or proton conducting membranes. 3. Oxyfuel combustion processes Combustion of fossil fuels and biomass in pure O2 results in formation of CO2 and H2O as combustion products. H2O can easily be separated from the combustion gas by condensation at low temperatures. Conventional O2-production by air liquefaction requires high investment costs and results in a significant efficiency drop of about 10 % points for a power plant. Membrane systems offer a high potential for the supply of pure oxygen for combustion processes while providing a drop in efficiency penalties. High temperature (>800ºC) ceramic membrane systems with both ionic and electronic conductivity are attractive materials due to the high selectivity of these systems for oxygen separation. 1.3 Object and outline of this thesis Object of this thesis Inorganic membranes are promising candidates for the gas separation in the above mentioned power plant concepts to capture CO2. Mixed oxygen ion and electronic conductive membranes have potential for the oxyfuel process (O2/N2 separation) and microporous inorganic membranes have high prospects for both pre- and postcombustion concepts. Microporous inorganic membranes will be the topic of this thesis. The general aim is to prepare inorganic microporous hydrothermal stable membranes for separating power plant gasses such as H2/CO2 or CO2/N2. These aims can be subdivided into: 5
1 Introduction and aims Selection of membrane material The selection of the membrane materials must fulfil the requirements of chemical, mechanical and hydrothermal stability in combination with high permeation of one of the species and a high separation factor. o Zeolite material with narrow pore size distributions will be selected for the separation of H2/CO2 or CO2/N2. All silica pore free dodecasil 1H and decadodecasil 3R zeolite types may fulfil this role. The focus on zeolites in this thesis is mainly on the material research. o Sol-gel derived TiO2 and ZrO2 materials can be alternatives to state of the art SiO2 membranes for both pre- and postcombustion applications. Preparation of sol-gel derived membranes The primary aim of these sol-gel derived TiO2 and ZrO2 materials is to prepare functional membrane layers with significant permselectivity for the above mentioned applications. Characterisation of membranes Characterisation of the Sol-gel derived membranes will be studied through gas permeance measurements. The membrane permeability setup must be designed and build-up to study the single gas permeation and selectivity performance. The hydrothermal stability must be investigated in order to evaluate the applicability of such membranes for pre- and postcombustion CO2 capture. Outline In Chapter 2 “Theoretical background”, the inorganic gas separation membranes are discussed. These inorganic membranes are subdivided in to dense and porous membranes based on the transport mechanism. The selection of the membrane materials is based on the properties of microporous membranes found in literature. This is followed by the characterisation methods to study microporous materials and membranes. In Chapter 3 “Experimental”, the material synthesis, the membrane preparation and the characterisation procedures of the equipment are described. Chapter 4 “Results and discussion” contains chemical and physical properties of the selected zeolites and sol-gel based materials, the microstructural properties of membrane layers and membrane permeation performance. The aims will be correlated with the final results and the future prospective is given in Chapter 5 “Conclusions and recommendations”. 6
Page 1 and 2: Mitglied der Helmholtz-Gemeinschaft
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4 Results and discussion Intensity
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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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