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Sacerdote-Peronnet, Myriam. "Etude cristallochimique d'interactions adsorbant-adsorbat dans des zéolithes présentant la topologie MFI : applications aux systèmes MFI-P-xylène et MFI-benzène." Lyon 1, 1992. http://www.theses.fr/1992LYO10028.
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Ce travail porte sur la mise en evidence d'interactions adsorbant/adsorbat (adsorbat=p-xylene, benzene) dans des materiaux microporeux zeolithiques polycristallins presentant la topologie mfi (silicalite, zsm-5). Des etudes par diffraction x et neutronique sur poudres et par modelisation theorique (minimisation d'energie basee sur les modeles de buckingham et de lennard-jones) ont abouti aux resultats suivants: dans le cas du systeme mfi/n p-xylene, il existe trois composes definis pour n=2, 4 et 8 molecules/maille, deux domaines diphases (0 n 2 et 4 n 8) et une solution solide (2 n 4). Entre 0 et 4 molecules/maille, les especes adsorbees occupent les intersections des canaux droits et en zig-zag. Dans la phase saturee (n=8), les molecules remplissent l'ensemble des canaux. Dans le cas du systeme mfi/n benzene, il se forme au moins cinq composes definis pour n=4, 6, 7, 7. 2 et 8 molecules/maille, trois domaines diphases (4 n 6, 6 n 7 et 7 n 7. 2) et une solution solide (7. 2 n 8). Jusqu'a n=4, le benzene est situe aux intersections. Dans le complexe mfi/6 benzene, 4 molecules occupent les intersections et 2 les canaux en zig-zag. Dans la phase saturee (n=8), le benzene ne remplit que les intersections et les canaux droits
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Deforth, Uwe. "Beitrag zur trockenen Synthese von MFI-Zeolithen und zeolithanalogen Materialien mit MFI-Struktur." [S.l. : s.n.], 2000. http://ArchiMeD.uni-mainz.de/pub/2000/0028/diss.pdf.
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Andersson, Charlotte. "Factors affecting MFI membrane quality /." Luleå : Division of Chemical Technology, Department of Chemical Engineering and Geosciences, Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1544/2007/41/.
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Öhrman, Olov. "Structured MFI film catalysts and adsorbents." Doctoral thesis, Luleå, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16949.
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A method originally developed at the division of Chemical Technology, Luleå University of Technology was tailored for the preparation of well-defined ZSM-5 films and zoned MFI films on supports suitable for catalysis and adsorption applications. Films were grown on monoliths, ceramic foams, alumina beads, soda glass beads and quartz glass. The supports were seeded with silicalite-1 crystals and hydrothermally treated in a single or several steps. The materials were evaluated by scanning electron microscopy, x-ray diffraction, N2 and NO2 sorption, x-ray photoelectron spectroscopy, ICP-AES, p-xylene isomerization and cracking of 1,3,5-tri-isopropylbenzene. The thickness of the continuous films could be controlled from 110 nm to 9 µm. Zoned MFI films were prepared from precursor ZSM-5 films by overgrowth with silicalite-1. A multi-step synthesis protocol was used to prevent excessive bulk crystallization. Ultrasound treatment was beneficial for removal of loosely attached crystals on top of the zeolite films. Defects such as cracks and open grain boundaries were observed by SEM and in concert, mesopores were observed by N2 sorption. Model parameters were fitted to experimental data from catalytic test reactions and these parameters indicated that thicker films contained more defects, probably in the form of open grain boundaries and cracks (mesopores) as observed by SEM and N2 sorption. Films supported on quartz were more catalytically active than films on alumina and soda glass. This was attributed to partial poisoning of the acid sites in the films on the latter two substrates, probably due to solid-state ion exchange of impurities such as alkali metals from the alumina and soda glass support to the film. As expected, thicker films possessed higher diffusion resistance than thin films. Surprisingly, a higher external activity was observed after zoning. This was attributed to formation of mesopores, migration of aluminum from the precursor ZSM-5 film to the external surface, and increased surface roughness upon zoning. ZSM-5 films supported on monoliths were successfully tested for NO2 sorption. As expected, the adsorption capacity per g zeolite was independent of film thickness. Formation of NO was observed as a result of NO2 adsorption on strong sites. Thicker films resulted in higher diffusion resistance as expected. The present work has resulted in substantial and valuable new fundamental understanding of the performance of thin molecular sieve film catalysts and adsorbents. These findings may facilitate development of novel materials for industrial applications.Godkänd; 2005; 20061004 (ysko)
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Öhrman, Olov G. W. "Structured MFI film catalysts and adsorbents /." Luleå : Luleå University of Technology, 2005. http://epubl.luth.se/1402-1544/2005/07.
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Jareman, Fredrik. "Properties and modeling of MFI membranes /." Luleå, 2004. http://epubl.luth.se/1402-1544/2004/011.
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Lindmark, Jonas. "Tailoring of MFI membranes for enhanced selectivity." Licentiate thesis, Luleå : Luleå tekniska universitet/Tillämpad kemi och geovetenskap/Kemisk teknologi, 2006. http://epubl.ltu.se/1402-1757/2006/56/LTU-LIC-0656-SE.pdf.
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Lindmark, Jonas. "Modification of MFI membranes for enhanced selectivity /." Luleå : Division of Chemical Engineering, Luleå University of Technology, 2009. http://pure.ltu.se/ws/fbspretrieve/3092805.
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Fouladvand, Shahpar. "Study of MFI zeolite membrane for CO2 separation." Licentiate thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59614.
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Nowadays, the need and interest for renewable sources of energy has increased. Biogas is a renewable source of energy that can be considered as a sustainable substitute for natural gas. Biogas is mainly composed of CH4 and CO2, and normally the CO2 content of the gas has to be reduced as it decreases the calorific value of the gas and it may also cause corrosion in pipes and other equipment. Most today’s technologies used for upgrading biogas have been adapted from upgrading of natural gas. However, these technologies are best suited for large scale operation; whereas, production of biogas is typically several orders of magnitude smaller. This leads to high costs for removal of CO2 from biogas and consequently, new efficient technologies for upgrading biogas should be developed. Membrane-based separations are generally considered as energy efficient and are suitable for a wide range in scale of production due to their modular design. Zeolite membranes have been singled out as especially attractive membranes for gas separations. In this work, we therefore study separation of CO2 from CH4 and H2 using zeolite MFI membranes. The performance of a high-silica (Si/Al ca. 139) MFI membrane for CO2/CH4 separation was investigated in a wide temperature range i.e. 245 K to 300 K. The separation factor increased with decreasing temperatures as is typically the case for adsorption governed separations. The highest separation factor observed was about 10 at 245 K. The CO2 permeance was very high in the whole temperature studied, varying from ca. 60 × 10-7 mol s-1 m -2 Pa-1 at the lowest temperature to about 90 × 10-7 mol s-1 m -2 Pa-1 at the highest temperature studied. The CO2 permeance was higher than that reported previously in the open literature for this separation. Modeling of the experimental data revealed that the membrane performance was adversely affected by pressure drop over the support, whereas the effect of concentration polarization was small. Removing the former effect would improve both the permeance and selectivity of the membrane. In order to investigate the impact of the aluminum content on the performance of MFI membranes for the CO2/CH4 separation, MFI membranes with different Si/Al ratios were prepared. Increasing the aluminum content makes the zeolite II more polar which should increase the CO2/CH4 adsorption selectivity. Again the effect of temperature on the performance was investigated by varying the temperature in a range almost similar as above. Altering the Si/Al ratio in MFI zeolite membranes indeed changed the separation performances. At the lower temperatures the separation performance increased with increasing aluminum content in the zeolite as a result of larger adsorption selectivity. However, as the temperature was decreased, the selectivity of the membrane with the highest aluminum content went through a maximum, whereas for the other membranes the selectivity continued to increase with decreasing temperature under the conditions studied. At the same time, the CO2 permeances were high for all membranes studied and for the membrane with the highest selectivity, the CO2 permeance increased from 65 × 10-7 to 100 × 10-7 mol s-1 m -2 Pa-1 with increasing temperature. High-silica MFI membranes were also evaluated for CO2/H2 separation, which is critical for syngas purification and H2 production. The highest CO2 permeance at the feed pressure of 9 bar was about 78 × 10-7 mol s-1 m -2 Pa-1 at around 300 K, which is one or two order of magnitude higher than those reported previously in the literature. By decreasing the temperature, separation factor reached its highest value of 165 at 235 K. In summary, zeolite membranes show great potential for CO2 separation from industrial gases, in particular for CO2 removal from synthesis gas. For the CO2/CH4 separation the selectivity of the MFI membranes should be improved or other frameworks relying on molecular sieving e.g. the CHA framework should be explored.
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Axon, Sean Alexander. "MFI-type zeolites synthesized in non-alkaline media." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240100.
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Kamaloo, Elaheh. "Molecular Modeling of Adsorbed NDMA in MFI Zeolites." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/299.
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N-Nitrosodimethylamine (NDMA), which is a carcinogenic and toxic N-nitrosamine, can be found in water resources associated with a multitude of processes in various industrial facilities or merely as a by-product of water or wastewater treatment. Therefore, the removal of NDMA from drinking water represents an important human safety and public health concern. The present paper presents a density functional theory study of NDMA adsorption in all-silica MFI, Na-ZSM-5 and H-ZSM-5 zeolites. The stability of NDMA inside the zeolite pores was investigated by calculating the amount of energy released during adsorption. Various configurations of adsorbed NDMA to the zeolites were investigated, predominantly at the intersection of straight and sinusoidal channels. The strength of the adsorption energies followed the order H-ZSM5 > Na-ZSM-5 > all-silica MFI. NDMA has a dipole moment and the strongest binding of NDMA occurred through the interactions of the negatively charged O atom of the molecule to positive atoms of the zeolite. Similar calculations were performed for water adsorption in these three zeolites. The adsorption energy of water to these three structures followed the order Na-ZSM5 > H-ZSM-5 > all-silica MFI. We also incorporated van der Waals corrections in the simulations, which had the effect of stabilizing NDMA within the zeolite channels, but did not significantly change the relative stability of the different adsorption geometries. It was concluded that H-ZSM-5 is the best choice to remove NDMA because it is strong enough to adsorb NDMA and it is not too strong in adsorption of water molecules.
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Bourdin, Vincent, Stefano Brandani, Alfeno Gunadi, Hervé Jobic, Cordula Krause, Jörg Kärger, and Wolfgang Schmidt. "Diffusion of n-alkanes in MFI-type zeolites." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196416.
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Takaba, Hiromitsu, Atsushi Yamamoto, Kikuko Hayamizu, and Shin-ichi Nakao. "Gas diffusion in polycrystalline MFI-type zeolite membranes." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-196691.
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Korelskiy, Danil. "Development of permporometry for analysis of MFI membranes." Licentiate thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26311.
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Zeolite membranes exhibiting high flux and high selectivity are of major interest for potential future applications. In order to achieve high flux and high selectivity, the zeolite film must be thin (< 1 µm) and free from flow-through defects. The development of thin defect free zeolite membranes requires powerful tools for characterization of flow-through defects in the membranes. Permporometry is one of the most straightforward and powerful techniques for characterization of flow-through pores in ceramic membranes. In permporometry, the flow of a non-condensable gas, e.g., helium, through the membrane is monitored as a function of the activity of a strongly adsorbing compound, e.g., hydrocarbon.In the present work, MFI membranes prepared by a seeding method were characterized by permporometry using helium as the non-condensable gas and n-hexane or benzene as the adsorbing compound. In order to appreciate permporometry data, the membranes were also characterized by scanning electron microscopy (SEM), single gas permeation and separation experiments. The permporometry data were then compared to the SEM morphology of the membranes, permeances of different probe molecules and membrane separation performance.In order to determine the conditions of the permporometry experiment leading to blocking of zeolite pores, a model describing helium transport in the zeolite pores in the presence of n-hexane or benzene was developed. The model is based on percolation theory and knowledge of the adsorption isotherms and adsorption sites for n-hexane and benzene in the zeolite pores. Parameters needed in the model were estimated by Density Functional Theory (DFT) using a Local-Density Approximation (LDA), the most sophisticated theory yet applied to this system. Based on the permporometry data, it was demonstrated that the model could adequately describe helium transport in zeolite pores in the presence of the hydrocarbons.The sensitivity of the permporometry technique towards the defect size has been improved considerably. It was revealed that high quality MFI membranes prepared in the present work contained mainly micropore defects which are most like the defects in the zeolite crystal lattice (intracrystalline defects).The work has shown how permporometry data could be used to estimate the area distribution of the flow-through defects in the membranes. The results on the defect distribution were corroborated by the SEM observations and the separation experiments. The width of cracks, including support cracks, and open grain boundaries observed by SEM was in excellent agreement with the defect width estimated from permporometry data. A straightforward correlation was observed between separation data and permporometry data, i.e. membranes of higher quality according to permporometry analysis exhibited greater separation performance. Also, the permeance of molecules diffusing through defects in the membrane in the separation experiment was found to scale with the permeance of helium through the defects measured in the permporometry experiment. In addition, this work showed that single gas permeance ratios could not detect slight variations in the membrane quality. For membranes with similar however slightly different amount of defects, the ratios are mainly affected by the membrane thickness and support morphology.To summarise, the present work demonstrates that permporometry data adequately reflect membrane quality and that permporometry is a very powerful technique for MFI membrane characterization.Godkänd; 2011; 20110512 (dankor); LICENTIATSEMINARIUM Ämnesområde: Kemisk teknologi/Chemical Technology Examinator: Professor Jonas Hedlund, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: PhD, senior researcher Olov Öhrman, ETC, Piteå Tid: Fredag den 17 juni 2011 kl 10.00 Plats: C305, Luleå tekniska universitet
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Jareman, Fredrik. "MFI-molecular sieve membranes : synthesis, characterization and modelling." Licentiate thesis, Luleå tekniska universitet, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17718.
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This work concerns evaluation by permeation measurements and modeling of thin (<2µm) MFI molecular sieve membranes and, to a smaller extent, synthesis of such materials. The membranes have been synthesized on graded a-alumina microfiltration filters using The seed film method. Scanning electron microscopy and x-ray diffraction were used for characterization in addition to permeation measurements. Mathematical models describing membrane flux for real membranes and defect distributions were developed. Defect distributions were calculated from porosimetry data and were further used for prediction of single gas permeation characteristics for real membranes. The models confirm the experimental findings, with respect to ideal selectivities as a measurement of membrane quality. Membrane permeation simulations indicate increasing ideal selectivities, with increasing film thickness, for quotients containing SF6. Thereby a high quality membrane could possess low ideal selectivities. This finding was confirmed by comparing experimental data of several membranes with varying thickness. The correlation between multi component separation data and commonly used quality criteria was investigated. It was found that commonly used single gas permeation quotients (ideal selectivity) between light inorganic gases, especially those containing sulphurhexaflouride (SF6), is less appropriate for membrane quality measurement. The porosimetry experiment showed on the other hand a good agreement between experimental data and separation performance of the membranes, as expected. ZSM-5 membranes with low aluminum content and silicalite-1 membranes with similar material properties, such as defect distribution and thickness were evaluated with multi component hydrocarbon isomers permeation. The ZSM-5 membrane had lower permeances and a slightly better butane isomer separation performance than the silicalite-1 membrane. The latter membrane showed a minimum in separation selectivity between two C6 isomers whereas the ZSM-5 membrane showed an almost constant selectivity, independent of temperature, but with lower permeances. ZSM-5 membranes with a high aluminum content catalyzed the formation of diethylether and ethylen at temperatures exceeding 150°C from a water/ethanol mixture. The membrane separated a mixture of C4 isomers with good performance at elevated temperatures. However these membranes suffered from temperature instability problems.Godkänd; 2002; 20070224 (ysko)
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Takaba, Hiromitsu, Atsushi Yamamoto, Kikuko Hayamizu, and Shin-ichi Nakao. "Gas diffusion in polycrystalline MFI-type zeolite membranes." Diffusion fundamentals 2 (2005) 106, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A13393.
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Leroy, Frederic H. R., Hervé Jobic, Bernard Rousseau, and Alain H. Fuchs. "Self-diffusion of n-alkanes in MFI-type zeolites." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194594.
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Novak, Sara. "Síntese de materiais Micro/Mesoporosos hierárquicos com estrutura MFI /." Araraquara, 2018. http://hdl.handle.net/11449/153109.
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Orientador: Celso Valentim SantilliCoorientador: Thiago Faheina Chaves
Banca: Regina Célia Galvão Frem
Banca: Wellington Henrique Cassinelli
Resumo: Este trabalho descreve o estudo de uma nova metodologia de síntese para obtenção de zeólitas MFI contendo uma estrutura hierárquica de poros. A porosidade hierárquica é uma propriedade que aumenta a acessibilidade dos reagentes aos sítios ativos dos cristais zeolíticos, sendo importante na melhora do desempenho desses materiais em diversas aplicações como adsorção, catálise e troca iônica. São vários os métodos que abordam a utilização de organossilanos como geradores de porosidade hierárquica mas poucos são os estudos que abordam esses compostos sendo empregados em sistemas de síntese bifásicos, por exemplo, em sistemas microemulsionados. Neste trabalho, a metodologia de síntese consistiu primeiramente na funcionalização de núcleos zeolíticos com três diferentes organossilanos em uma etapa de pré-cristalização a 40oC: octiltrietoxisilano (C8), dodeciltrietoxisilano (C12) e hexadeciltrimetoxisilano (16). A análise estrutural dos materiais foi feita por meio das técnicas de difração de raios X, RMN no estado sólido, termogravimetria e espectroscopia na região do infravermelho, enquanto as propriedades texturais foram avaliadas por fisissorção de nitrogênio e porosimetria de mercúrio. O organossilano C8 apresentou os resultados mais promissores levando a obtenção de zeólitas MFI contendo poros hierárquicos (Vmicro ~ 0,130 cm3g-1, Vmeso ~ 0,211 cm3g-1) e elevadas área externa específica (Sext ~ 273 m2g-1) e hidrofobicidade (θ ~ 140o). Este organossilano foi então utilizado no es... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This work describes a new approach to the synthesis to obtain MFI zeolites with hierarchical porosity. Hierarchical porosity is a property that improves the accessibility of reactants to active sites in the zeolite crystals, which is important in different technical applications like as adsorptive or catalytic processes. There are many methods using organosilane to create the hierarquical porosity but are few studies that explores this compounds in two-phase systems like a micro-emulsion systems. In this work, the methodology first consisted of zeolite nucleus functionalization with three organosilanes in a temperature at 40 oC: octyltriethoxysilane (C8), dodecyltrietoxisilane (C12) and hexadecyltrimethoxysilane (C16). The structural analysis of the materials was done by the using of X-ray diffraction, solid state NMR, thermogravimetry and infrared spectroscopy, while the textural properties were evaluated by nitrogen physisorption and mercury porosimetry. The octyltriethoxysilane demonstrated the best results to obtainment of MFI zeolites containing hierarchical pores (Vmicro ~ 0,130 cm3g-1, Vmeso ~ 0,211 cm3g-1), large surface area (Sext ~ 273 m2g-1) and hydrophobic profile (θ ~ 140o). This organosilane was used in the study of addition of an oil phase (dodecane) after the nucleus functionalization. The oil phase was stabilized by functionalized and hydrophobic zeolite nucleus around the oil phase during the hydrothermal crystallization process at 150o C. In this stage, the... (Complete abstract click electronic access below)
Mestre
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Brace, Shelley. "Synthetic and structural studies of high silica MFI zeolites." Thesis, Keele University, 2017. http://eprints.keele.ac.uk/3778/.
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A systematic series of high-silica fluoride MFI zeolites were efficiently synthesised using a variety of shape and size structure directing agents. The effects of these structure directing agents on the zeolite synthesised have been studied by the complementary use of X-ray diffraction and solid state NMR. These 14N, 13C and 29Si NMR experiments yield information about the orientation of the structure directing agent within zeolite pores. They also identify covalently bonded fluoride in the form of pentacoordinated silicon whereby the first case of static and dynamic ordering of fluoride in the same zeolite is discovered by changing the structure directing agent. A two-dimensional solid state NMR experiment has also been used to study 13C isotopically labelled silicalite-1 synthesised using n-methyltributylammonium iodide. The double cross polarisation (DCP) experiment allows the distance to be determined between the structure directing agent and silicon framework for the first time in a zeolite system using NMR. This experiment has the potential to be replicated for silicalite-1 zeolites synthesised using alternate structure directing agents or for other zeolites systems.
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Culfaz, Pinar Zeynep. "Synthesis Of Mfi Type Zeolite Membranes In A Continuous System." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606267/index.pdf.
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MFI type zeolites, are the most widely studied zeolites for membrane separations. Conventionally, zeolite membranes are prepared in batch systems by hydrothermal synthesis in autoclaves. This method has several disadvantages for use in industrial scale for the synthesis of membranes with large areas and complex geometries that are commonly used in membrane modules.
The objective of this study is to prepare MFI type zeolite membranes on tubular alumina supports in a continuous system where the synthesis solution is circulated through the tubular supports. Syntheses were carried out using clear solutions, at atmospheric pressure and at temperatures below 100°C. The membranes were characterized by N2, SF6, n-butane and isobutane permeances, X-ray diffraction and scanning electron microscopy. A 2-&
#956
m membrane was synthesized using the composition 80SiO2: 16TPAOH: 1536H2O at 95°
C in the continuous system. The membrane showed N2 permeance of 4.4 x 10-7 mol/m2.s.Pa and N2/SF6 selectivity of 11. The membrane synthesized in the batch system showed a N2 permeance of 3.4 x 10-7 mol/m2.s.Pa and a N2/SF6 selectivity of 27. Both membranes showed n-butane/isobutane mixture (50%-50%) selectivities of about 6 at temperatures of 150 and 200°
C. Among many zeolite membranes reported in literature, these membranes are one of the few zeolite membranes synthesized in a flow system and the first MFI type membranes synthesized in a continuous flow system with circulation of the synthesis solution. The permeances and selectivities of the membranes synthesized in the continuous system are comparable with the MFI type membranes synthesized in batch systems in literature.
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Pal, Prem. "Oxidative amination of propane over gallium modified H-MFI catalysts." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250415.
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Meyer, Horst. "The Modular Flighttest Instrumentation / MFI 90 A Helicopter Measuring System." International Foundation for Telemetering, 1989. http://hdl.handle.net/10150/614643.
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International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, CaliforniaFor investigations in the field of stability and control or handling qualities of helicopters, a Flighttest Instrumentation System is presented which combines some aspects of modern engineering. The aim was to create a system which is easy to understand and easy to handle, furthermore, allows the integration of future techniques and works with a maximum of performance under the given conditions. The system is modular. Good flexibility is guaranteed by the use of microprocessors combined with transducers in the front end modules. To avoid active or passive interference with the systems of the helicopter, the transportation of digital data is done by means of optical waveguides. The technique of processor control and data transmission is designed for future requirements like rising numbers of signals or bitrates. An "intelligent" transducer is shown together with its communication with the main onboard computer. On the other hand an overview is given of the onboard recording systems like Floppy Disc and Winchester, which have the advantage of readable computer data storage. For a quicklook telemetry a computer standardized protocol is also used as a method of online monitoring of digital data in the ground station.
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Harper, Stuart Edward. "Single-dish intensity mapping with the QUIJOTE MFI and GBT." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/singledish-intensity-mapping-with-the-quijote-mfi-and-gbt(3bb4234f-46b7-4191-aec0-408345be1d97).html.
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Today, there are only a limited number of surveys of the sky at 1 to 20 GHz. These frequencies lie below the all-sky surveys of WMAP and Planck, but are critical in constraining the spectral slope of Galactic synchrotron emission. Knowledge of the large-scale spectral morphology of Galactic synchrotron emission is critical in the understanding of the interstellar medium and the weak signal from the polarised cosmic microwave background. Recently, ground based observations from S-PASS, C-BASS and the QUIJOTE Multifrequency Instrument (MFI) have been populating these missing frequencies. This thesis presents the first QUIJOTE MFI maps of the Northern sky in total intensity at 11, 13, 17 and 19 GHz, and the first single-dish mapping observations of Lynds dark cloud, LDN1622 at 5 and 13.7GHz. The observations from both instruments are used to probe the nature of spinning dust emission on degree and arcminute scales within the Galaxy. A full data reduction and calibration pipeline for QUIJOTE MFI time-ordered-data is described. The absolute flux density scale uncertainty of the MFI data is between 2 and 3 per cent. The pipeline characterises key properties of the MFI, such as the RFI sources, beams, bandpasses, 1/f noise and more. A key part of the pipeline was the development of an MPI ready Destriping map-maker and a maximum-likelihood map-maker. The map-making code can be applied to a range of different single-dish instruments and is used to reduce both the QUIJOTE MFI wide-survey maps of the Northern sky, and the GBT arcminute resolution raster observations of LDN 1622. A detailed discussion is given on the simulations used to test the integrity of the map-making implementation. Parametric model fitting to the SEDs of four spinning dust emission regions is performed. The MFI wide-survey maps are used in conjunction with existing multifrequency 1degree survey data. The addition of MFI maps is used to confirm the previously tentative spinning dust emission source LDN 1582/84. The mean peak frequency of spinning dust emission over the four spinning dust sources is found to be ⟨νsp⟩ = 27.2 +/- 0.7 GHz, and the mean ratio of the peak spinning dust brightness over the dust optical depth is ⟨Asp/τ250⟩ = 1.24 +/- 0.18 × 104 Jy/τ250. Spectral index maps are derived from the MFI wide-survey data in combination with 408 MHz and WMAP 23 GHz data. These maps are used to further quantify the ubiquity of spinning dust emission throughout the Galaxy. The results show that the median flux density spectral index within the inner Galactic disk for |b| < 2° is 0.24 +/- 0.07. This implies that at 23 GHz, spinning dust emission contributes 25 +/- 5 per cent of the total integrated emission within the inner disk of the Galaxy.
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Dincer, Eser. "Effect Of Seeding On The Properties Of Mfi Type Zeolite Membranes." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606393/index.pdf.
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The effect of seeding on the properties of alumina supported MFI membranes was investigated in this study. Membranes were synthesized from clear solutions with a molar batch composition of TPAOH:9.80SiO2:0.025NaOH:0.019Al2O3: 602.27H2O:39.16C2H5OH on bare and seeded alumina supports at 130oC in autoclaves. The amount of seed on the support surface was changed between 0.6 mg/cm2 and 6.9 mg/cm2 by vacuum seeding method, which provided uniform and closely packed seed layers.
Membranes were characterized by XRD and SEM, and by measuring single gas permeances of N2, SF6, n-C4H10 and i-C4H10. The quality of membranes was evaluated on the basis of N2/SF6 ideal selectivity. Membranes, which showed N2/SF6 ideal selectivity higher than 40, were considered to be good quality, comprising few defects. Good quality membranes were also used to separate butane isomers.
Membranes synthesized on seeded supports had compact and uniform MFI layer if the seed amount is less than 1.0 mg/cm2 on the support surface. Membranes that were synthesized on the supports coated with higher amount of seed crystals showed an asymmetric structure with a dense and uniform MFI layer at the top, the support at the bottom and a seed layer between.
Half of the membranes synthesized on seeded supports had N2/SF6 ideal selectivity higher than 40. These membranes exhibited n-C4H10/i-C4H10 separation selectivities between 5 and 27 and 8 and 21 at room temperature and at 200oC, respectively. High ideal and separation selectivities showed that membranes did not include non-zeolitic pores.
Membranes synthesized on bare support had non-uniform MFI layer. Those membranes showed N2/SF6 ideal selectivities below Knudsen selectivity, indicating the existence of large non-zeolitic pores in the MFI layer.
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Farzaneh, Amirfarrokh. "Adsorption Properties of MFI-Type Zeolite Films for Upgrading of Biofuels." Doctoral thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-60958.
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With the depleting reservoirs of fossil fuels, increasing environmental concerns for flue-gas emissions from fossil-fuel combustion and growing world population, the need for the development of new sustainable fuels is higher than ever. However, to be able to compete with today’s mature technologies for production of fuels from fossil sources, new efficient processing alternatives for upgrading of biofuels must be developed. Bio-fuels produced by e.g. fermentative processes are promising alternatives to traditional chemicals and fuels produced from fossil sources. Recovery of biofuels by selective membranes and adsorbents has been identified as promising energy efficient recovery routes. In this work, adsorption properties of MFI-type zeolite films were studied using in situ ATR-FTIR spectroscopy in order to understand the adsorption properties of these zeolites. Single component adsorption isotherms of butanol and water vapor were determined at different temperatures using ATR-FTIR spectroscopy. The Langmuir and Sips model were successfully fitted to experimental data, and the fitted parameters obtained in this work were in very good agreement with values reported in the literature. Adsorbed amounts of butanol and water from binary vapor mixtures were extracted from the infrared spectra as well as the adsorption selectivities. The silicalite-1 film prepared in fluoride medium found to be significantly more butanol selective due to the exceptionally low density of defects in the structure. Biogas (methane) is another promising biofuel that is commonly produced by anaerobic degradation of biomass. However, before it may be used, contaminants have to be removed from the gas; two of the most abundant contaminants in biogas are carbon dioxide and water vapor. Adsorption of a ternary mixture of methane, carbon dioxide and water vapor in zeolite Na-ZSM-5 has been studied at various compositions and temperatures using ATR–FTIR spectroscopy. The amount adsorbed determined from experimental data were compared to predictions by the Ideal Adsorbed Solution Theory (IAST). This result confirms that Na-ZSM-5 could be a promising membrane material for upgrading of biogas.
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Laloué, Nicolas, Catherine Laroche, Hervé Jobic, and Alain Méthivier. "Kinetic Monte Carlo study of binary diffusion in MFI-type zeolite." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193418.
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Romanova, Ekaterina, Bärbel C. Krause, Alexander Stepanov, Baten Jasper M. van, Rajamani Krishna, Jörg Kärger, and Dieter Freude. "1 H NMR signal broadening in spectra of MFI type zeolites." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194086.
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Akomas, George Chiagozie. "Effects of geographical location on MFI lending behaviour in developing countries." Thesis, University of Huddersfield, 2018. http://eprints.hud.ac.uk/id/eprint/34683/.
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Ever since the United Nations declared 2005 the year of micro-credit and linked it to the Millennium Development Goals, and especially on poverty reduction, there has been a series of studies looking at factors affecting the flow of credit down the poverty line. This is of particular importance because in spite of the success of Microfinance Institutions such as the Grameen Bank in Bangladesh and BancoSol in Mexico, evidence shows that many Microfinance Institutions do not reach down the poverty line but tend to cluster at the top. Developing several hypotheses using the elements of the neo-institutional theory, this study looks at how geographic location affects how Microfinance Institutions target their clients and the moderating effect that their regional context has on other factors. This is analysed using an unbalanced panel of 6, 645 observations drawn from 443 MFI institutions in 81 countries divided into 5 regions for the time period 2000-2014. An ordered logit regression was run using the target markets as the ordinal dependable variables. Based on the arguments of the neo-institutional theory, this study builds on previous ones by using a larger sample size (and number of years) to examine how the regional context affects the relationship between institutional quality and the selective lending behaviour of MFIs in 81 developing countries. An ordered logit regression was carried out using an unbalanced panel of 6645 observations from 443 MFI institutions across six regions from 2000-2014 against a broad range of company, country, regional and global specific variables. The results indicate that the geographic locations affects how MFIs lend down the poverty line with MFIs in and those in Eastern Europe and Central America less likely to lend to down the poverty line. The study found that the regional context also plays a big role in how institutional factors affect MFI lending practises with certain factors being more relevant in some regions than in others. This study also makes a case for using target markets as a better measure for depth of outreach as opposed to the more popular loan sizes and identifies the role that rural population growth and mobile phone penetration play in increasing depth of outreach of microfinance.
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Laloué, Nicolas, Catherine Laroche, Hervé Jobic, and Alain Méthivier. "Kinetic Monte Carlo study of binary diffusion in MFI-type zeolite." Diffusion fundamentals 6 (2007) 24, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14198.
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Romanova, Ekaterina, Bärbel C. Krause, Alexander Stepanov, Baten Jasper M. van, Rajamani Krishna, Jörg Kärger, and Dieter Freude. "1 H NMR signal broadening in spectra of MFI type zeolites." Diffusion fundamentals 6 (2007) 68, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14248.
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KASIM, ZAINAL ABIDIN. "Aromatisation d'hexanes sur des catalyseurs du type gallium sur zeolithes mfi." Paris 6, 1994. http://www.theses.fr/1994PA066161.
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L'aromatisation du n-hexane a ete realisee sur les catalyseurs h. Zsl. 5 et ga/h. Zsm. 5 pour verifier le mecanisme de formation des aromatiques et le role du gallium. Les reactions ont ete realisees a pression atmospherique entre 723-823 k et a vhsv de 51. 1 a 434. 7 h pour 0,25 g de catalyseur. Une etude cinetique, basee sur les donnees experimentales du schema initial de la reaction a montre que le craquage du nc#6 etait la reaction predominante avec les catalyseurs h. Zsm. 5. Sa vitesse est a peu pres 4 a 5 fois plus rapide que la deshydrogenation entre 723-823 k. Cependant, avec l'introduction du gallium le processus de deshydrogenation est ameliore. Il est environ 5 a 7 fois plus rapide que le craquage lequel n'a pas ete significativement affecte par la presence du gallium. L'autre reaction primaire est l'isomerisation de nc#6 en ic#6 qui a ete legerement augmentee avec l'addition du gallium. Cependant le principal role du gallium est d'augmenter la vitesse du processus de deshydrogenation. Cette etude a aussi montre qu'il y a une teneur maximale en gallium (entre 2. 46 et 3. 90 wt%) au-dessus de laquelle il n'est pas aussi efficace. Sur les catalyseurs h. Zsm. 5, le cracking de nc#6 en propane et propylene via un mecanisme ion carbenium, une scission, un transfert d'hydrogene et l'oligomerisation des olefines legeres, la cyclisation, la deshydrogenation via un transfert d'hydrogene sur les sites acides du catalyseur vers les aromatiques est le chemin prefere d'aromatisation. D'autre part, les catalyseurs contenant du gallium, ameliorent la deshydrogenation de nc#6 en c#6= et la deshydrogenation des produits cycliques d'oligomerisation en aromatiques par les sites de gallium. L'ensemble de ces mecanismes est propose pour la formation d'aromatiques sur les 2 catalyseurs h. Zsm. 5 et ga/h. Zsm. 5
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Munnoch, Alexander Leishman. "Methanol dehydration using MFI : the role of framework composition and binder." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4757/.
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Methanol dehydration is currently of industrial interest as a means of dimethyl ether production. Pertinently, dimethyl ether may be used as an alternative LPG fuel. This reaction is acid catalysed and in this study a number of microporous catalysts, containing the unique MFI framework structure, have been investigated. Attention has also been directed towards the application of binders and their effects. Temperature ranges for selective dimethyl ether formation were found to be 150- 275 °C over H-ZSM-5, 300-350 °C over Na-ZSM-5 and 150-350 °C over γ-Al2O3 catalysts (where ZSM-5 = MFI zeolites). Comparison of commercial ZSM-5 materials with a wide range of SiO2/Al2O3 ratios (23-1500) showed methanol dehydration to increase with increasing framework aluminium content. B-MFI, Fe- MFI and Ga-MFI zeotypes were synthesised for comparison to zeolites. 11B and 71Ga MAS-NMR measurements showed boron and gallium to be tetrahedrally coordinated within their MFI frameworks. The following ranking of methanol dehydration activity: Al > Ga > Fe > B was observed. Large scale zeolite and zeotype applications require the use of binders such as silicas and aluminas to provide desirable physical properties. Despite their necessity in scale-up, zeolite binding and its effects have been largely ignored and there is a general misconception that they are inert components. Silica binders were found to decrease the activity of the catalyst by dilution, alkali metal poisoning and pore filling. Sodium content had a stronger negative effect than binder dilution and pore blockage on the methanol dehydration activity. Furthermore, increasing sodium content resulted in decreasing extra-framework aluminium formation. Arrenhius plots of sodium-exchanged zeolites showed increasing sodium content to decrease the number of zeolite active sites. The methanol dehydration activity of H-ZSM-5 (1500) was increased in the presence of an alumina binder and the method of binding had little effect on the catalytic activity. A small degree of aluminium insertion into the zeolite framework was indicated by 27Al and 29Si MAS-NMR in bound and aluminium impregnated systems. 27Al and 29Si MAS-NMR also showed the change of the nature of active sites in Arrenhius plots of extremely calcined and extremely steamed aluminium-impregnated ZSM-5 (1500) catalysts to be the result of zeolite dealumination.
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Pereira, Elen Maria Feliciano. "Híbridos ureasil-poliéter conjugados com zeólitas MFI para acetilação do glicerol /." Araraquara, 2019. http://hdl.handle.net/11449/183485.
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Orientador: Celso Valentim SantilliBanca: Leila Aparecida Chiavacci Favorin
Banca: Eduardo Ferreira Molina
Resumo: Neste trabalho a metodologia sol-gel foi utilizada para a preparação de materiais híbridos orgânico-inorgânicos (HOI) à base de óxido de poli-etileno (PEO), ligado de forma covalente com o agente acoplador 3(isocianatopropil) - trietoxisilano (IsoTREOS) conjugados com um material zeolítico do tipo MFI, visando aplicações como catalisador para a reação de acetilação do glicerol e assim agregar valor a esse coproduto gerado na produção do biodiesel. O objetivo desta dissertação é demonstrar que o sinergismo entre híbridos do tipo siloxano-poliéter e as zeólitas pode ser explorado na produção de hidrogéis com atividade catalítica. As análises por Microscopia Eletrônica de Varredura (MEV) evidenciaram a homogeneidade na dispersão do material zeolítico na matriz híbrida Os difratogramas de raios-X apresentaram os picos característicos da estrutura cristalina da zeolita ZSM-5 após a conjugação com a matriz U-PEO. Os resultados de Calorimetria Diferencial de Varredura (DSC) revelaram que não ocorre uma mudança significativa na temperatura de transição vítrea (Tg), após a conjugação da matriz híbrida com a zeólita e revelaram uma diminuição do pico endotérmico associado à fusão dos domínios cristalinos do PEO1900, indicando uma possível interação matriz-zeólita. As análises por Espectroscopia no Infravermelho com Transformada de Fourier (FTIR) confirmaram a interação entre a matriz híbrida e a zeólita pelo deslocamento das bandas associadas ao oxigênio tipo éter não coordenado. Medid... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In this work the sol-gel methodology was used for the preparation of organic-inorganic hybrid (HOI) materials based on polyethylene oxide (PEO) - covalently bonded with the coupling agent 3 (isocyanatopropyl) triethoxysilane (IsoTREOS) conjugate with a zeolitic material of the MFI type, aiming at applications as catalyst for glycerol acetylation reaction and thus add value to this byproduct generated in biodiesel production. The objective of this dissertation is to demonstrate that the synergism between siloxane-polyether hybrids and zeolites can be explored in the production of catalytic activity hydrogels. Scanning Electron Microscopy (SEM) analyzes showed homogeneity in the dispersion of zeolite material in the hybrid matrix. XDR patterns showed the characteristic peaks of the ZSM-5 zeolite crystal structure after conjugation with the U-PEO matrix. Differential Scanning Calorimetry (DSC) results revealed that no significant change in glass transition temperature (Tg) occurs after conjugation of hybrid matrix with zeolite and revealed a decrease in endothermic peak associated with fusion of crystalline domains of PEO1900., indicating a possible matrix-zeolite interaction. Fourier Transform Infrared Spectroscopy (FTIR) analyzes confirmed the interaction between the hybrid matrix and zeolite by shifting the bands associated with uncoordinated ether oxygen. Small-angle X-ray Scattering (SAXS) measurements showed that the starting reagents in the solketal production reaction w... (Complete abstract click electronic access below)
Mestre
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Hanebuth, Marc. "Vernetzte Transportpfade für die Simulation des Stofftransports durch Kompositmembranen des MFI-Zeolithtyps." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972029540.
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Kassaee, Mohamad Hadi. "Internal surface modification of zeolite MFI particles and membranes for gas separation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44906.
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Zeolites are a well-known class of crystalline oxide materials with tunable compositions and nanoporous structures, and have been used extensively in catalysis, adsorption, and ion exchange. The zeolite MFI is one of the well-studied zeolites because it has a pore size and structure suitable for separation or chemical conversion of many industrially important molecules. Modification of zeolite structures with organic groups offers a potential new way to change their properties of zeolites, beyond the manipulation of the zeolite framework structure and composition.
The main goals of this thesis research are to study the organic-modification of the MFI pore structure, and to assess the effects of such modification on the adsorption and transport properties of zeolite MFI sorbents and membranes. In this work, the internal pore structure of MFI zeolite particles and membranes has been modified by direct covalent condensation or chemical complexation of different organic molecules with the silanol defect sites existing in the MFI structure. The organic molecules used for pore modification are 1-butanol, 1-hexanol, 3-amino-1-propanol, 1-propaneamine, 1,3-diaminopropane, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. TGA/DSC and 13C/29Si NMR characterizations indicated that the functional groups were chemically bound to the zeolite framework, and that the loading was commensurate with the concentration of internal silanol defects. Gas adsorption isotherms of CO2, CH4, and N2 on the modified zeolite materials show a range of properties different from that of the bare MFI zeolite. The MFI/3-amino-1-propanol, MFI/2-[(2-aminoethyl)amino]ethanol, and MFI/benzenemethanol materials showed the largest differences from bare MFI. These properties were qualitatively explained by the known affinity of amino- and hydroxyl groups for CO2, and of the phenyl group for CH4. The combined influence of adsorption and diffusion changes due to modification can be studied by measuring permeation of different gases on modified MFI membranes.
To study these effects, I synthesized MFI membranes with [h0h] out-of-plane orientation on α-alumina supports. The membranes were modified by the same procedures as used for MFI particles and with 1-butanol, 3-amino-1-propanol, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. The existence of functional groups in the pores of the zeolite was confirmed by PA-FTIR measurements. Permeation measurements of H2, N2, CO2, CH4, and SF6, were performed at room temperature before and after modification. Permeation of n-butane, and i-butane were measured before and after modification with 1-butanol. For all of the studied gases, gas permeances decreased by 1-2 orders of magnitude compared to bare MFI membranes for modified membranes. This is a strong indication that the organic species in the MFI framework are interacting with or blocking the gas molecule transport through the MFI pores.
A detailed fundamental study of the CO2 adsorption mechanism in modified zeolites is necessary to gain a better understating of the adsorption and permeation behavior of such materials. Towards this end, an in situ FTIR study was performe.For the organic molecules with only one functional group (1-butanol, benzenemethanol, and 1-propaneamine), physical adsorption was found - as intuitively expected - to be the only observed mode of attachment of CO2 to the modified zeolite material. Even in the case of MFI modified with 1,3-diaminopropane, only physical adsorption is seen. This is explained by the isolated nature of the amine groups in the material, due to which only a single amine group can interact with a CO2 molecule. On the other hand, chemisorbed CO2 species are clearly observed on bare MFI, and on MFI modified with 3-amino-1-propanol or 2-[(2-aminoethyl)amino]ethanol. Specifically, these are carbonate-like species that arise from the chemisorption of CO2 to the silanol group in bare MFI and the alcohol groups of the modifying molecule. The possibility of significant contributions from external surface silanol groups in adsorbing CO2 chemisorbed species was ruled out by a comparative examination of the FTIR spectra of 10 μm and 900 nm MFI particles modified with 2-[(2-aminoethyl)amino]ethanol.
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Meyer, Horst M. "Helicopter Testing Using the PC-Based MFI 90 Flight Test Instrumentation System." International Foundation for Telemetering, 1995. http://hdl.handle.net/10150/611606.
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International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, NevadaDLR realizes flight testing under the rough environmental conditions on board of helicopters. Beside the necessary data about the behavior of the base helicopter the main interest concerns information about the rotor system. After explaining the measuring technique the computer integrated Rotor data acquisition system is presented which communicates with the Central computer inside the helicopter via serial data line. The Central computer that has to gather and process also the signals from the base is a modified PC-type computer. It is demonstrated how to use office PC components for this purpose. These have the advantage to be inexpensive and always and everywhere available. The Central computer is a 486er type now. Necessary modifications for airworthy certification are explained. This technique includes on board recording and telemetry. An intelligent LC display is presented which gives the test pilots the necessary information about their tasks. It is a simply modified notebook controlled only by handling cursor keys. In addition pilots have the chance to fly "head up" by using an LC display which origins from an LCD projection panel.
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Millot, Benoît. "Étude du transport d'hydrocarbures saturés dans des membranes zéolithiques de structure MFI." Lyon 1, 1998. http://www.theses.fr/1998LYO19008.
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L'objectif de ce travail etait de caracteriser et de modeliser les processus de transport des alcanes dans les membranes zeolithiques de structure mfi. Ce travail a ete mene en deux temps. Tout d'abord, une caracterisation des equilibres d'adsorption des alcanes dans les zeolithes de type mfi a ete necessaire. La mesure directe d'isothermes d'adsorption ainsi que la thermodesorption programmee nous ont permis d'obtenir un grand nombre de donnees : capacite d'adsorption, variations d'enthalpie et d'entropie isosteriques d'adsorption. L'interpretation de ces resultats a l'aide d'un modele d'equilibre a deux types de sites a montre les effets preponderants de l'entropie d'adsorption sur la localisation des molecules dans la structure. Dans un second temps, nous nous sommes consacres a des mesures de permeation des alcanes dans les membranes zeolithes. Il est apparu que ces materiaux presentaient une selectivite importante pour separer les alcanes lineaires des alcanes branchees. Bien que les comportements observes soient tres complexes, l'utilisation de nos donnees d'equilibre couplees avec les equations generalisees de maxwell-stefan a permis de simuler les resultats et d'extraire des coefficients de diffusion pour les hydrocarbures lineaires et monobranches. Nous avons egalement pu obtenir une representation preliminaire du comportement de la permeation en melange.
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Doyemet, Yves-Jean. "Aromatisation de l'éthane et du propane sur des zéolithes du type MFI." Poitiers, 1989. http://www.theses.fr/1989POIT2307.
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Les zeolites les plus appropriees a la deshydrogenation aromatisante des hydrocarbures du titre seraient du type suivant: une zeolite hzsm5 tres acide et presentant de nombreux sites deshydrogenants (oxyde de gallium)
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Seive, Alain. "Synthèse et caractérisation de gallosilicates de type MFI en présence d'ions fluorure." Mulhouse, 1989. http://www.theses.fr/1989MULH0128.
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Le but de ce travail fut d'étudier la synthèse de zéolithes (gallozéolites) de type structure MFI en présence d'ion fluorure (pH8), ou Gaiii substitue partiellement Siiv dans la charpente de tétraèdres de ces matériaux. Les propriétés acides (du type Bronsted) et les dimensions (de l'ordre de 6A) des canaux interconnectés de cette structure cristalline sont utilisés en catalyse acide et notamment pour l'aromatisation des gaz légers C2 et C4 (en présence ou non d'oléfines) en benzène, toluène et xylène. Selon la nature des réactifs engagés dans le milieu réactionnel, l'élément gallium peut être concentré au coeur des cristaux, au réparti de façon quasi-homogène dans le solide. Différentes caractérisations (RMN RAM 29Si, 69Ga, 71Ga) ont permis de montrer que l'élément gallium est incorporé dans un environnement tétraédrique d'oxygène de la charpente. Nous avons également observé (RMN RAM 29Si, 69Ga) l'extraction partielle du gallium hors de la charpente après calcination et réhydratation. Enfin différentes hypothèses concernant la nature du fluor contenu dans les zéolithes du type (Si, Ga)-MFI ont été formulées (RMN RAM 19F) : paires ioniques TPA+F-, NH4+F-, NH4+HF2- ou du type Si-F-Ga ou Si-OH-F-Ga. Les zéolithes de type MFI synthétisés en milieu fluorure et en présence de sels solubles d'au moins deux des éléments Gaiii, Aliii et FEiii et d'une source de silice sont caractérisées par un ordre d'incorporation qui est le suivant : Ga>Fe>Al. Ces incorporations ont été interprétées par les différences de complexations de ces éléments trivalents vis-à-vis des ions fluorures et hydroxyles. Au cours de différentes synthèses mises en œuvre, une phase secondaire du type phyllosilicate (mica) a été recueillie
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Cao, Zishu. "MFI-Type Zeolite Nanosheets Laminated Membranes for Ion Separation in Aqueous Solutions." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1593269786201009.
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Sadat, Rezai Seyed Alireza. "Water selective MFI zeolite membranes for application in the Fischer Tropsch Synthesis." Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/6699.
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Selective removal of water from the Fischer-Tropsch Synthesis (FTS) during reaction may allow the use of a cobalt catalyst with crystal size <6 nm hence increasing the catalyst activity. Zeolite membranes are a potential route to in-situ water removal due to their chemical and thermal stability under FTS reaction conditions. Zeolite membranes with a low Si/ Al ratio are hydrophilic. It has been hypothesised that reducing the Si/ Al ratio will result in increased water selectivity and permeance. It is also hypothesised that the separation process can be modelled using the MaxwellStefan (MS) formulation. MFI zeolite membranes were synthesised on a-alumina supports, of varying Si/ Al ratio. Two synthesis techniques were used: viz. with and without the assistance of structure directing agents. The membrane physical properties were characterised by SEM and XRD. Membrane quality was evaluated using n-hexane porosimetry. Single gas and mixture separations were carried out. A trans-membrane pressure gradient was applied in single gas measurements. Binary and ternary mixture separations were carried out using a model reaction mixture that approximates FTS conditions. This mixture was fed to a Wicke-Kallenbach cell. The total pressure on both sides of the membrane was equal, with a sweep gas applied to remove the permeate. Single gas permeation measurements on a blank support shows that viscous and knudsen flow are the dominant transport mechanisms in the support. A single gas permeation model for the zeolite membranes show that viscous and knudsen flow still dominate in pure component measurements. This due to the high flux through the zeolite films. During mixture separations viscous and knudsen flow are negligible as there is no pressure gradient. Comparing pure component and binary mixture separations the flux of hydrogen decreases by more than two orders of magnitude for the binary case. In the binary system water adsorption results in blockage of pores hence hydrogen permeance is reduced. Binary H20/H2 separation selectivity increases with decreasing Si/ Al ratio. Increasing temperature results in a decrease in this selectivity. Water adsorption decreases with increasing temperature hence hydrogen can permeate faster. With the addition of n-hexane as a third component, permeance of water and hydrogen decrease, however ternary H20/H2 separation selectivity increases. The Maxwell-Stefan model developed does not predict binary hydrogen permeation well. Permeance is much higher than predicted by the model possibly due to defects. Ternary hydrogen permeance is however more accurately predicted. Water and n-hexane permeances are predicted well by the model.
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Darwiche, Ali. "Membranes zéolithiques de type MFI pour l'extraction et la séparation de l'hydrogène." Thesis, Mulhouse, 2010. http://www.theses.fr/2010MULH3174.
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Cette étude se situe dans le cadre des recherches menées par le CEAEA sur la production massive d'hydrogène, sans émission de gaz à effet de serre, via un cycle thermo-chimique de décomposition de l'eau couplé à une source de chaleur à haute température d'origine nucléaire. Dans le cas particulier du cycle dit« Iode-Soufre», on doit extraire H2 à partir d'un mélange H2/HI/H20 très corrosif, opération pour laquelle des procédés membranaires ont été proposés. L'objectif de ce travail est le développement de membranes zéolithiques de type MFI susceptibles d'être utilisées dans ce contexte. Nous présentons les différents matériaux utilisés, la méthodologie de synthèse de couches minces de Silicalite-1 et de ZSM-5 synthétisée sans structurant organique, les techniques de caractérisation des membranes. Une étude cinétique nous a permis d'optimiser et de contrôler les conditions d'obtention de ces couches minces déposées sur des substrats tubulaires en Ti02 et plans en Al2O3-α. De nombreuses expériences de perméation ont été réalisées, pour des gaz simples (H2, He, Ar, N 2, C02, SF6) et des mélanges gazeux (H2/H20/Ar) et (H2/H20/HI/Ar). Les effets de la température, de la pression amont, de l'épaisseur et de la longueur de la couche mince ainsi que du gaz vecteur ont été étudiés en détail. Il apparaît que la présence de molécules d'H20 dans le système joue un rôle prépondérant sur la perméation des autres moléculesIn the general context of massive and "carbon free" hydrogen production studies, the aim of this work was the development of zeolitic MFI membranes for hydrogen extraction and separation. The methodology of synthesis, the membranes characterization techniques as well as the permeation experimental setup are presented. Optimization and control of the elaboration of Ti02 supported Silicalite-1 and template free ZSM-5 membranes have been reached. Details of the full kinetic study that we performed are given. Numerous permeation experiments, involving pure gas (H2, He, Ar, N2, C02, SF6) and mixtures (H2/H20/Ar) and (H2/H 20/HI/Ar) have been carried on. The effects of temperature, feed pressure, thickness and length of the membranes, as well as the role of the sweeping gas have been emphasized. In the case of gas mixtures, the presence of H20 molecules appears to be a predominant factor
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Keung, Michael Pak-On. "The synthesis and characterisation of MFI (template free), MTW and M41S zeolitic materials." Thesis, Brunel University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332804.
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Binder, Tomas, Christian Chmelik, Jörg Kärger, and Wolfgang Schmidt. "Microscopic analysis of phase transition effects during benzene sorption in MFI type zeolites." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185519.
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Binder, Tomas, Christian Chmelik, Jörg Kärger, and Wolfgang Schmidt. "Microscopic analysis of phase transition effects during benzene sorption in MFI type zeolites." Diffusion fundamentals 16 (2011) 64, S. 1-2, 2011. https://ul.qucosa.de/id/qucosa%3A13807.
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Kasula, Medha. "Synthesis and catalytic testing of Sn-MFI zeolite crystallized using different tin precursors." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593185207803411.
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Van, Niekerk Anelia. "Direct crystallisation of hydroxysodalite and MFI membranes on α-alumina supports / Anelia van Niekerk." Thesis, North-West University, 2005. http://hdl.handle.net/10394/4331.
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Humplik, Thomas. "Investigating the adsorption and transport of water in MFI zeolite pores for water desalination." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62533.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71-74).
The permeability of reverse osmosis membranes is limited by the diffusive transport of water across a non-porous polyamide active layer. Alternatively, fabricating a microporous active layer capable of rejecting salt ions while allowing for water transport would increase the permeability while maintaining high salt rejection. Zeolites provide a model porous network which is capable of performing this type of molecular sieve separation. However, a lack of understanding of the mechanisms that govern transport within the zeolite pore network as well as an insufficient control of membrane synthesis has limited the performance of past zeolite-based membranes. In this thesis, we seek to understand the mechanisms of water adsorption and transport in MFI-type zeolite pores through experimentation. Water adsorption on the surface and inside of the pore network was characterized by thermogravimetric analysis for varying Si/Al ratio zeolites. We estimated that the pore volume filled is -71% for a 23 Si/Al ratio MFI zeolite, -25% for an 80 Si/Al ratio MFI zeolite, and 0% for an infinite Si/Al ratio MFI zeolite. In addition, we characterized the transport of water into the MFI zeolite pore network by applying an increasing hydraulic pressure and measuring the change in volumetric displacement. We were able to corroborate the adsorbed pore volume from the TGA experiments and estimated that the pore volume filled was ~72% for a 23 Si/Al ratio MFI zeolite and ~34% for an 80 Si/Al ratio MFI zeolite. We also observed that the volumetric infiltration rate did not have an effect on the infiltration characteristics, which is distinctly different from continuum hydrodynamic behavior. Future work will focus on testing the water permeation and salt rejection of these types of zeolites. We have made significant progress in the fabrication of defect-free zeolite membranes. We also plan on investigating the adsorption and transport of water in MFI zeolite pores by using molecular dynamics simulations.
by Thomas Humplik.
S.M.
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Joshi, Rutuja U. "Synthesis and Catalytic Testing of Lewis Acidic Nano-MFI Zeolites to Overcome Diffusion Limitations." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1511871858531586.
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Courthial, Lucile, Arnaud Baudot, Elsa Jolimaitre, Melaz Tayakout, and Christian Jallut. "Moments method applied to the In-Situ characterisation of normal butane mass transfer in MFI zeolite membranes: Moments method applied to the In-Situ characterisation of normalbutane mass transfer in MFI zeolite membranes." Diffusion fundamentals 2 (2005) 88, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A13373.
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