Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(MFI zeolites). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters

1. Margeriat, Alexandre. Conversion catalytique des vapeurs de pyrolyse et molécules modèles : Catalytic conversion of pyrolytic vapors and model molecules.

Degree: Docteur es, Chimie, 2017, Lyon

La pyrolyse rapide de biomasse lignocellulosique produit des bio-huiles avec des rendements élevés mais ces liquides contiennent de nombreux composés oxygénés, une acidité élevée et de ce fait sont instables. Un hydrotraitement poussé de ces huiles est nécessaire avant qu'elles puissent être utilisées comme combustibles liquides. Afin de réduire le coût et d'améliorer les performances de l'hydrotraitement ultérieur, plusieurs stratégies ont été proposées pour réduire les teneurs en oxygène et en acides, comme l'ajout d'un lit catalytique après la pyrolyse. La conversion catalytique des vapeurs de pyrolyse permet une désoxygénation partielle avant la condensation des vapeurs. Dans ce contexte, nous avons étudié la conversion de molécules modèles, l'acide acétique et le gaïacol, sur différents catalyseurs acides afin d'identifier des phases actives performantes et de comprendre les mécanismes réactionnels. Dans un deuxième temps, un test de pyrolyse semi-continu combiné avec un réacteur catalytique a été conçu et mis en place et les meilleurs catalyseurs acides sélectionnés pour les molécules modèles ont été testés pour la conversion de bois de hêtre. Après conversion, un protocole de séparation des fractions a été appliqué et les fractions gaz, liquide et solide ont été caractérisées par différentes méthodes (?-GC, GC×GC, GPC, RMN…). Une attention particulière a été portée à la quantification des monomères dans la fraction liquide par GC×GC. Les bilans massiques atteignent plus de 90% et des bilans carbones ont été également réalisés dans les différentes fractions. L'ensemble des caractérisations et la comparaison entre pyrolyse avec et sans étape catalytique permet d'améliorer la compréhension du rôle du catalyseur dans la conversion des vapeurs de pyrolyse

Fast pyrolysis of biomass yields bio-oils with high levels of oxygen-containing components, high acidity and low stability. Further upgrading of these oils is necessary before they can be used as liquid fuels. Several low-cost strategies have been proposed for reducing the oxygen and acid contents including the catalytic conversion of pyrolytic vapors before vapor condensation. In this context, a first step in this work was the study of model molecules conversion, acetic acid and guaiacol, on different acid catalyst to understand reaction mechanisms and determine the best catalyst. In a second time, a semi-continuous pyrolysis test combined with a catalytic reactor was built and use to test the best acid catalysts found on model molecules, for the conversion of beech wood chips. A product recovery protocol was implanted to recover all the gas, liquid and solid fractions. Those fractions were characterized in depth by various techniques (?-GC, GC×GC, GPC, RMN…). A special focus was made on the quantification of monomers in the bio-oils by GC×GC. Mass balance reached 90% and carbon balance were established for some experiments. The performed characterizations as well as the comparison between catalytic and thermal experiments allowed to get more insights in the…

Advisors/Committee Members: Schuurman, Yves (thesis director), Laurenti, Dorothée (thesis director).

Subjects/Keywords: Pyrolyse rapide; Catalyse; Bio-huiles; Zéolithes MFI; Analyse GCxGC; Acide acétique; Gaïacol; Fast pyrolysis; Catalysis; Bio oil; MFI zeolites; GCxGC analysis; Acetic acid; Guaiacol; 541

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Margeriat, A. (2017). Conversion catalytique des vapeurs de pyrolyse et molécules modèles : Catalytic conversion of pyrolytic vapors and model molecules. (Doctoral Dissertation). Lyon. Retrieved from http://www.theses.fr/2017LYSE1340

Chicago Manual of Style (16th Edition):

Margeriat, Alexandre. “Conversion catalytique des vapeurs de pyrolyse et molécules modèles : Catalytic conversion of pyrolytic vapors and model molecules.” 2017. Doctoral Dissertation, Lyon. Accessed October 16, 2019. http://www.theses.fr/2017LYSE1340.

MLA Handbook (7th Edition):

Margeriat, Alexandre. “Conversion catalytique des vapeurs de pyrolyse et molécules modèles : Catalytic conversion of pyrolytic vapors and model molecules.” 2017. Web. 16 Oct 2019.

Vancouver:

Margeriat A. Conversion catalytique des vapeurs de pyrolyse et molécules modèles : Catalytic conversion of pyrolytic vapors and model molecules. [Internet] [Doctoral dissertation]. Lyon; 2017. [cited 2019 Oct 16]. Available from: http://www.theses.fr/2017LYSE1340.

Council of Science Editors:

Margeriat A. Conversion catalytique des vapeurs de pyrolyse et molécules modèles : Catalytic conversion of pyrolytic vapors and model molecules. [Doctoral Dissertation]. Lyon; 2017. Available from: http://www.theses.fr/2017LYSE1340

2. Kassaee, Mohamad Hadi. Internal surface modification of zeolite MFI particles and membranes for gas separation.

Degree: PhD, Chemical Engineering, 2012, Georgia Tech

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… Advisors/Committee Members: Nair, Sankar (Committee Chair), Sholl, David S. (Committee Co-Chair), Beckham, Haskell (Committee Member), Chance, Ronald R. (Committee Member), Jones, Christopher W. (Committee Member).

Subjects/Keywords: Organic functionalized zeolite; Zeolite MFI; Gas separation; Nanopourous materials; CO2 separation; Membrane separation; Zeolites

…adsorption, and ion exchange.11,12 The zeolite MFI is one of the well-studied zeolites because it… …cannot withstand. 1.2. Zeolite MFI Among different zeolites, a large effort in the literature… …are in Ångstrom.(Reproduced with permission from Cejka et al 3) MFI type zeolites… …are highly siliceous with Si/Al ratios from about 10 to infinity. MFI zeolites are reported… …technique. Zeolites such as MFI are known to contain silanol defects in their structure. The… 

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Kassaee, M. H. (2012). Internal surface modification of zeolite MFI particles and membranes for gas separation. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/44906

Chicago Manual of Style (16th Edition):

Kassaee, Mohamad Hadi. “Internal surface modification of zeolite MFI particles and membranes for gas separation.” 2012. Doctoral Dissertation, Georgia Tech. Accessed October 16, 2019. http://hdl.handle.net/1853/44906.

MLA Handbook (7th Edition):

Kassaee, Mohamad Hadi. “Internal surface modification of zeolite MFI particles and membranes for gas separation.” 2012. Web. 16 Oct 2019.

Vancouver:

Kassaee MH. Internal surface modification of zeolite MFI particles and membranes for gas separation. [Internet] [Doctoral dissertation]. Georgia Tech; 2012. [cited 2019 Oct 16]. Available from: http://hdl.handle.net/1853/44906.

Council of Science Editors:

Kassaee MH. Internal surface modification of zeolite MFI particles and membranes for gas separation. [Doctoral Dissertation]. Georgia Tech; 2012. Available from: http://hdl.handle.net/1853/44906


Delft University of Technology

3. Taboada, J.B. Direct Oxidation of Benzene to Phenol: investigation of the active iron species in [Fe,Al]MFI catalysts by 57Fe Mössbauer spectroscopy.

Degree: 2006, Delft University of Technology

Steam-treated isomorphously substituted [Fe,Al]MFI zeolite is known to exhibit superior catalytic performance in the direct oxidation of benzene to phenol, using N2O as oxidant (BTOP). However, despite extensive efforts, the nature of the active sites in the [Fe,Al]MFI catalyst for the BTOP reaction is still largely unknown. However, recent investigations have shown strong indication that extra-framework iron species in the [Fe,Al]MFI zeolite are the catalytically active constituents in the BTOP reaction. To elucidate the active sites, this study investigates the relationship between the structure and activity of [Fe,Al]MFI catalysts in the BTOP reaction. Several isomorphously substituted [Fe,Al]MFI zeolites, varying in iron and aluminum concentrations, were successfully prepared via hydrothermal synthesis. All as-synthesized [Fe,Al]MFI zeolites were enriched with 57Fe isotope to enhance the Mauer effect, and thus providing an excellent signal-to-noise ratio. The evolution of iron from framework to extra-framework position during sequential post-activation treatments is investigated with 57Fe Mauer spectroscopy. In addition, the redox property of the extra-framework iron species formed after steam-treatment is studied by in situ Fe K-edge XANES. The catalytic performance of steam-treated [Fe,Al]MFI zeolites, with varying iron and aluminum concentrations, is evaluated in the direct oxidation of benzene to phenol, using N2O as oxidant, as well as in the N2O decomposition. From characterization and activity data, it can be inferred that (i) not all extra-framework iron species formed after steam-treatment of the [Fe,Al]MFI zeolites are active in the BTOP reaction; (ii) active iron species in BTOP reaction are preferably formed in samples with low iron concentration, while higher N2O conversions were achieved for [Fe,Al]MFI catalysts with increasing iron loading; (iii) the occurrence of catalyst deactivation, most likely due to coke formation, is more favorable in the presence of aluminum; while in the N2O decomposition, catalysts with higher aluminum concentration exhibit superior performance; and, (iv) aluminum does not play a role in the BTOP catalysis. Finally, in situ 57Fe Mauer studies show that there are several active sites for the direct oxidation of benzene to phenol. These active sites are most likely small clusters of iron species with low nuclearity (e.g. enzyme-like systems). Thus, this heterogeneous catalyst is simply heterogeneous in terms of the extra-framework iron species formed after steam-treatment, which makes it difficult to establish a direct relationship between structure and activity in the BTOP reaction. Advisors/Committee Members: de Schepper, I.M..

Subjects/Keywords: al]mfi zeolites; isomorphous substitution; steam-treatment; benzene to phenol; extra-framework iron species; 57fe mössbauer spectroscopy

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Taboada, J. B. (2006). Direct Oxidation of Benzene to Phenol: investigation of the active iron species in [Fe,Al]MFI catalysts by 57Fe Mössbauer spectroscopy. (Doctoral Dissertation). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21

Chicago Manual of Style (16th Edition):

Taboada, J B. “Direct Oxidation of Benzene to Phenol: investigation of the active iron species in [Fe,Al]MFI catalysts by 57Fe Mössbauer spectroscopy.” 2006. Doctoral Dissertation, Delft University of Technology. Accessed October 16, 2019. http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21.

MLA Handbook (7th Edition):

Taboada, J B. “Direct Oxidation of Benzene to Phenol: investigation of the active iron species in [Fe,Al]MFI catalysts by 57Fe Mössbauer spectroscopy.” 2006. Web. 16 Oct 2019.

Vancouver:

Taboada JB. Direct Oxidation of Benzene to Phenol: investigation of the active iron species in [Fe,Al]MFI catalysts by 57Fe Mössbauer spectroscopy. [Internet] [Doctoral dissertation]. Delft University of Technology; 2006. [cited 2019 Oct 16]. Available from: http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21.

Council of Science Editors:

Taboada JB. Direct Oxidation of Benzene to Phenol: investigation of the active iron species in [Fe,Al]MFI catalysts by 57Fe Mössbauer spectroscopy. [Doctoral Dissertation]. Delft University of Technology; 2006. Available from: http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; urn:NBN:nl:ui:24-uuid:f4eb5c04-ae43-4e42-9947-e9829593de21 ; http://resolver.tudelft.nl/uuid:f4eb5c04-ae43-4e42-9947-e9829593de21

.