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You searched for subject:(Methanol dehydration). Showing records 1 – 2 of 2 total matches.

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1. Jiang, Qian. Direct dimethyl ether synthesis from CO2/H2 : Synthèse directe de diméthyle éther à partir de CO2/H2.

Degree: Docteur es, Catalyse hétérogène, 2017, Université de Strasbourg

DME est un carburant propre qui contribue à diminuer les émissions de gaz à effet de serre; il est aussi une molécule plate-forme pour le stockage d'énergie. L'objectif de la thèse est le développement de matériaux catalytiques bifonctionnels pour la synthèse directe de DME à partir de CO2/H2 à partir de Cu/ZnO/ZrO2 comme le catalyseur de la synthèse de méthanol à partir de CO2/H2 et Al-TUD-1 comme le catalyseur de déshydratation du méthanol en DME. Dans cette thèse, Al-TUD-1 a été étudiée comme un catalyseur de la déshydratation du méthanol en DME pour la première fois. Son activité en déshydratation du méthanol en DME augmente avec la diminution du rapport Si/Al. Les catalyseurs bifonctionnels ont été préparés par un procédé de dépôt par co-précipitation. Le SMSI a été démontré et était bénéfique pour la dispersion de cuivre métallique, la surface de cuivre métallique augmente avec le rapport Si/Al. Dans le même temps, on a observé le blocage des sites acides d'Al-TUD-1 par le cuivre. Afin d'exposer les sites acides d'Al-TUD-1, la méthode de « core-shell » a été adoptée pour préparer le catalyseur bifonctionnel. Elle aide à libérer la fonction acide en empêchant son blocage par le cuivre. Cette méthode de synthèse a été bénéfique pour la stabilité des particules de cuivre métalliques, mais des faibles conversions de CO2/H2 ont été observées en raison de l'inaccessibilité du noyau. Un autre catalyseur bifonctionnel a été préparé par une méthode de mélange physique pour comparaison. L'optimisation du catalyseur bifonctionnel Cu/ZnO/[email protected] pour la synthèse directe de DME à partir de CO2/H2 a permis d'éclairer les principaux paramètres affectant le contact intime de deux fonctions catalytiques: surface et dispersion du cuivre, les propriétés acide et basic, la présence d'eau et l'accessibilité des sites actifs pour les réactifs.

DME is a clean fuel that helps to diminish the emissions of green house gases; it is as well a platform molecule for the energy storage. The objective of the thesis is the development of bifunctional catalytic materials for the direct DME synthesis from CO2/H2 based on Cu/ZnO/ZrO2 as the methanol synthesis from CO2/H2 catalyst and Al-TUD-1 as the methanol dehydration to DME catalyst. In this thesis, Al-TUD-1 was investigated as the methanol dehydration to DME catalyst for the first time. The methanol dehydration to DME performance increases with the decrease of Si/Al ratio. The bifunctional catalysts were prepared by co-precipitation deposition method. The SMSI was demonstrated and was beneficial for the metallic copper dispersion, the metallic copper surface area increases with the Si/Al ratio. In the same time the blockage of acid sites of Al-TUD-1 by copper was observed. In order to expose the acid sites of Al-TUD-1, the core shell method was adopted to prepare the bifunctional catalyst. It helps to free the acid function preventing its blockage by copper. This method of synthesis was beneficial for the stability of metallic copper particles, but performed low conversions of CO2/H2…

Advisors/Committee Members: Roger, Anne-Cécile (thesis director).

Subjects/Keywords: DME; Hydrogénation du CO2; Déshydratation du méthanol; Al-TUD-1; DME; CO2 hydrogenation; Methanol dehydration; Al-TUD-1; 541.39

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

APA (6th Edition):

Jiang, Q. (2017). Direct dimethyl ether synthesis from CO2/H2 : Synthèse directe de diméthyle éther à partir de CO2/H2. (Doctoral Dissertation). Université de Strasbourg. Retrieved from http://www.theses.fr/2017STRAF041

Chicago Manual of Style (16th Edition):

Jiang, Qian. “Direct dimethyl ether synthesis from CO2/H2 : Synthèse directe de diméthyle éther à partir de CO2/H2.” 2017. Doctoral Dissertation, Université de Strasbourg. Accessed November 12, 2019. http://www.theses.fr/2017STRAF041.

MLA Handbook (7th Edition):

Jiang, Qian. “Direct dimethyl ether synthesis from CO2/H2 : Synthèse directe de diméthyle éther à partir de CO2/H2.” 2017. Web. 12 Nov 2019.

Vancouver:

Jiang Q. Direct dimethyl ether synthesis from CO2/H2 : Synthèse directe de diméthyle éther à partir de CO2/H2. [Internet] [Doctoral dissertation]. Université de Strasbourg; 2017. [cited 2019 Nov 12]. Available from: http://www.theses.fr/2017STRAF041.

Council of Science Editors:

Jiang Q. Direct dimethyl ether synthesis from CO2/H2 : Synthèse directe de diméthyle éther à partir de CO2/H2. [Doctoral Dissertation]. Université de Strasbourg; 2017. Available from: http://www.theses.fr/2017STRAF041


University of Michigan

2. Wilke, Trenton. Catalysis with Dispersed Cation-Exchanged Polyoxometalates.

Degree: PhD, Chemical Engineering, 2018, University of Michigan

Heterogeneous catalysts are complex materials that present challenges in understanding their physical and chemical properties as well as improving their performance in chemical processes. The pursuit of catalysts with well-defined active sites that are stable under practical reaction conditions may lead to the improved fundamental understanding of catalyst function at the molecular level and enable the development of catalysts tailored for a specific reaction. Polyoxometalates (POMs) supported on a high surface area support are model transition-metal oxide catalysts possessing well-defined, isolated, and tunable catalytic sites that are active for both selective oxidation and acid catalysis. POM acid and redox properties may be systematically varied by the replacement of a portion of POM protons with other cations, such as copper or sodium. The model catalyst system phosphomolybdic acid (H3PMo12O40) supported on fumed silica was used to evaluate the effects of cation exchange on POM properties and reactivity, for both oxidation and acid-catalyzed reactions. The as-prepared catalysts were characterized by a variety of techniques to confirm that the POMs were intact and well-dispersed on the silica surface and to quantify changes in POM reducibility and acid properties with cation addition. The interaction of POMs and the cations was evident by the variation of many POM properties with the incremental addition of counter-cations. The effect of cation addition on the POM catalytic activity was evaluated using parallel pathways of methanol dehydration to dimethyl ether and oxidation to formaldehyde and its derivatives as probe reactions. The catalytic activity of POMs for both the dehydration and oxidation of methanol decreased dramatically as cations (Na, Mg, Cu, or Al) replaced protons. The measured oxidation and dehydration rates over Na, Mg, and Cu exchanged POMs were remarkably similar, and the differences in the cation charge had little impact. Al-exchanged POMs tended to have a higher quantity of acid sites and higher TOF at comparable extents of cation exchange compared to the other cations. The perturbation of POM acid sites, via the introduction of counter-cations, was determined to be responsible for the decrease in the rates for both dehydration and oxidation of methanol. Although cation exchange was demonstrated to alter the POM reducibility, this had no observable effect on the oxidation activity of the cation-exchanged catalysts. Rather, the quantity of acid sites per POM was the primary reactivity descriptor for both the dehydration and oxidation of methanol over POMs, perhaps due to the presence of a proton-mediated intermediate in both the methanol dehydration and oxidation pathways over POMs. While cation addition does not result in the production of a more active catalyst, there are many exciting applications for a model catalyst with a well-defined and tunable structure. For example, activity coefficients were developed to describe the non-ideal behavior of POM acid sites with cation addition.… Advisors/Committee Members: Barteau, Mark A (committee member), Thompson, Levi Theodore (committee member), Bartlett, Bart (committee member), Linic, Suljo (committee member).

Subjects/Keywords: Polyoxometalate; Methanol oxidation and dehydration; Counter cation exchange; Acid site strength and quantity; Activity coefficients for heterogeneous catalysts; Chemical Engineering; Engineering

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

APA (6th Edition):

Wilke, T. (2018). Catalysis with Dispersed Cation-Exchanged Polyoxometalates. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/147603

Chicago Manual of Style (16th Edition):

Wilke, Trenton. “Catalysis with Dispersed Cation-Exchanged Polyoxometalates.” 2018. Doctoral Dissertation, University of Michigan. Accessed November 12, 2019. http://hdl.handle.net/2027.42/147603.

MLA Handbook (7th Edition):

Wilke, Trenton. “Catalysis with Dispersed Cation-Exchanged Polyoxometalates.” 2018. Web. 12 Nov 2019.

Vancouver:

Wilke T. Catalysis with Dispersed Cation-Exchanged Polyoxometalates. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2019 Nov 12]. Available from: http://hdl.handle.net/2027.42/147603.

Council of Science Editors:

Wilke T. Catalysis with Dispersed Cation-Exchanged Polyoxometalates. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/147603

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