Mechanistic Studies of Water Oxidation and Carbon Dioxide Reduction Using Transition Metal Catalysts with Protic Ligands PDF Download
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Author: Dalton Bodine Burks
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 292
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Book Description
The majority of energy produced in the world is derived from fossil fuels which are finite and have deleterious environmental effects. For a sustainable and environmentally-friendly energy future, alternative, renewable energy sources are desired. Two reactions that could have applications towards developing renewable energy sources are water oxidation to produce hydrogen and carbon dioxide reduction to form various products (e.g. formic acid or carbon monoxide); however, these reactions require catalysts to efficiently produce the desired products. Efforts to synthesize, characterize, and study catalysts for these reactions are discussed in this dissertation. The first chapter serves as an introduction to energy-related catalytic reactions. In Chapter 2, 6,6ʹ-dihydroxybipyridine (6,6ʹ-dhbp)-a protic ligand used with several metals to produce catalysts for energy-related reactions-is studied to determine its thermodynamic acidity. In the following chapter, 6,6ʹ-dhbp is used as a ligand with copper to form complexes that are water oxidation catalysts. Chapters 4 and 5 focus on iridium and ruthenium complexes containing new bidentate ligands composed of pyridinol and N-heterocyclic carbenes (NHCs). These complexes, along with an iridium complex of 6,6ʹ-dhbp, were used as catalysts for the hydrogenation of carbon dioxide to formate and the reverse dehydrogenation of formic acid to carbon dioxide and hydrogen. However, the complexes containing the new bidentate pyridinol-NHC ligands were found to be precatalysts as they undergo transformations and decomposition during the course of the reaction. A nickel-pincer complex with a protic CNC-pincer derived of pyridinol and NHCs was used as a photocatalyst for carbon dioxide reduction in Chapter 6. The protic state of the hydroxy group in the 4-position of the pyridine ring was determined to be important for catalysis, as the deprotonated hydroxy group results in 10 times the catalytic ability as the protonated form. In the penultimate chapter, ruthenium-pincer complexes that are active carbon dioxide photoreduction catalysts are studied mechanistically by UV/vis and IR spectroscopies. The most active catalyst was studied in greater detail with real-time IR spectroscopy to help elucidate potential reaction pathways. The final chapter serves as a conclusion to summarize the results discussed in the dissertation.
Author: Dalton Bodine Burks
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 292
Get Book Here
Book Description
The majority of energy produced in the world is derived from fossil fuels which are finite and have deleterious environmental effects. For a sustainable and environmentally-friendly energy future, alternative, renewable energy sources are desired. Two reactions that could have applications towards developing renewable energy sources are water oxidation to produce hydrogen and carbon dioxide reduction to form various products (e.g. formic acid or carbon monoxide); however, these reactions require catalysts to efficiently produce the desired products. Efforts to synthesize, characterize, and study catalysts for these reactions are discussed in this dissertation. The first chapter serves as an introduction to energy-related catalytic reactions. In Chapter 2, 6,6ʹ-dihydroxybipyridine (6,6ʹ-dhbp)-a protic ligand used with several metals to produce catalysts for energy-related reactions-is studied to determine its thermodynamic acidity. In the following chapter, 6,6ʹ-dhbp is used as a ligand with copper to form complexes that are water oxidation catalysts. Chapters 4 and 5 focus on iridium and ruthenium complexes containing new bidentate ligands composed of pyridinol and N-heterocyclic carbenes (NHCs). These complexes, along with an iridium complex of 6,6ʹ-dhbp, were used as catalysts for the hydrogenation of carbon dioxide to formate and the reverse dehydrogenation of formic acid to carbon dioxide and hydrogen. However, the complexes containing the new bidentate pyridinol-NHC ligands were found to be precatalysts as they undergo transformations and decomposition during the course of the reaction. A nickel-pincer complex with a protic CNC-pincer derived of pyridinol and NHCs was used as a photocatalyst for carbon dioxide reduction in Chapter 6. The protic state of the hydroxy group in the 4-position of the pyridine ring was determined to be important for catalysis, as the deprotonated hydroxy group results in 10 times the catalytic ability as the protonated form. In the penultimate chapter, ruthenium-pincer complexes that are active carbon dioxide photoreduction catalysts are studied mechanistically by UV/vis and IR spectroscopies. The most active catalyst was studied in greater detail with real-time IR spectroscopy to help elucidate potential reaction pathways. The final chapter serves as a conclusion to summarize the results discussed in the dissertation.
Author: Zaheer Masood
Publisher:
ISBN:
Category : Carbon dioxide mitigation
Languages : en
Pages : 0
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Book Description
A major contribution to global warming is CO2 emitted from the combustion of fossil fuels. Electrochemical processes can help to mitigate the elevated CO2 emissions through either the conversion of CO2 into value-added chemicals or the replacement of fossil fuels with clean fuels such as hydrogen produced from water oxidation. The present dissertation focuses on the mechanistic aspects of electrochemical processes. Electrochemical water oxidation is hindered by the low efficiency of oxygen evolution reaction (OER) at the anode whereas electrochemical reduction of CO2 (ERCO2) is hampered by high overpotentials and poor product selectivity. In this dissertation, we studied the catalytic activity of transition metal-based catalysts, including FeNi spinels, metal-oxide/copper, and d metal cyclam complexes, for both OER and ERCO2 using the density functional theory (DFT) computational approach. We report a combined effort of fabricating FeNi oxide catalysts and identifying the active component of the catalyst for OER. Our collaborators at the University of California, Santa Cruze fabricated a series of FeNi spinels-based materials including Ni(OH)Fe2O4(Cl), Ni(OH)Fe2O4, Fe(OH)Fe2O4(Cl), Fe(OH)Fe2O4, Ni(OH)O(Cl), Ni(OH)O and some show exceptional activity for OER. Combined experimental characterization and computational mechanistic study based on the computational hydrogen electrode (CHE) model revealed that Ni(OH)Fe2O4(Cl) is the active ensemble for exceptional OER performance. We also investigated CO2 reduction to C1 products at the metal-oxide/copper interfaces ((MO)4/Cu(100), M = Fe, Co and Ni) based on the CHE model. The effect of tuning metal-oxide/copper interfaces on product selectivity and limiting potential was clearly demonstrated. This study showed that the catalyst/electrode interface and solvent can be regulated to optimize product selectivity and lower the limiting potential for ERCO2. Applied potential affects the stability of species on the surface of the electrode. The proton-coupled electron transfer (PCET) equilibrium assumed in the CHE model does not capture the change in free energy under the influence of the applied potential. In contrast, the constant electrode potential (CEP) model captures changes in free energy due to applied potential, we applied the CEP model to ERCO2 and OER on (MO)4/Cu(100) and compared the results with those from the CHE model. The results demonstrate that the CHE and the CEP models predict different limiting potentials and product selectivity for ERCO2, but they predict similar limiting potentials for OER. The results demonstrate the importance of accounting for the applied potential effect in the study of more complex multi-step electrochemical processes. We also studied transition metal-based homogeneous catalysts for ERCO2. We examined the performance of transition metal(M)--cyclam(L) complexes as molecular catalysts for the reduction of CO2 to HCOO- and CO, focusing on the effect of changing the metal ions in cyclam on product selectivity (either HCOO- or CO), limiting potential and competitive hydrogen evolution reaction. Our results show that among the complexes, [LNi]2+ and [LPd]2+ can catalyze CO2 reduction to CO, and [LMo]2+ and [LW]3+ can reduce CO2 to HCOO-. Notably, [LMo]2+, [LW]3+, [LW]2+ and [LCo]2+ have a limiting potential less negative than -1.6 V and are based on earth-abundant elements, making them attractive for practical application. In summary, the dissertation demonstrates high-performance catalysts can be designed from earth-abundant transition metals for electrochemical processes that would alleviate the high CO2 level in the environment. On the other hand, completely reversing the increasing trend of CO2 level in the atmosphere requires a collective human effort.
Author:
Publisher: Academic Press
ISBN: 0128160837
Category : Science
Languages : en
Pages : 380
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Book Description
Water Oxidation Catalysts, Volume 74, the latest release in the Advances in Inorganic Chemistry series, presents timely and informative summaries on current progress in a variety of subject areas. This acclaimed serial features reviews written by experts in the field, serving as an indispensable reference to advanced researchers. Users will find this to be a comprehensive overview of recent findings and trends from the last decade that covers various kinds of inorganic topics, ranging from theoretical oriented supramolecular chemistry, to the quest for accurate calculations of spin states in transition metals. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Advances in Inorganic Chemistry series Includes the latest information on water oxidation catalysts
Author: Linbin Yao
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author:
Publisher:
ISBN: 9789174476262
Category :
Languages : en
Pages : 80
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Book Description
Author: Pierre Dixneuf
Publisher: John Wiley & Sons
ISBN: 3527656812
Category : Technology & Engineering
Languages : en
Pages : 438
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Book Description
Water is abundant in nature, non-toxic, non-flammable and renewable and could therefore be safer and economical for the chemical industry wherever it is used as a solvent. This book provides a comprehensive overview of developments in the use of water as a solvent for metal catalysis, illustrating the enormous potential of water in developing new catalytic transformations for fi ne chemicals and molecular materials synthesis. A group of international experts cover the most important metalcatalyzed reactions in water and bring together cutting-edge results from recent literature with the first-hand knowledge gained by the chapter authors. This is a must-have book for scientists in academia and industry involved in the fi eld of catalysis, greener organic synthetic methods, water soluble ligands and catalyst design, as well as for teachers and students interested in innovative and sustainable chemistry.
Author: Francesca Cardona
Publisher: Royal Society of Chemistry
ISBN: 1849738238
Category : Science
Languages : en
Pages : 304
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Book Description
This book deals with the search for environmentally benign procedures for the oxidation of alcohols and gives an overview of their transition-metal-catalyzed aerobic oxidation.
Author:
Publisher:
ISBN: 9789463326445
Category :
Languages : en
Pages : 160
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Author: Suyash Singh
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Over the past century, heterogeneous catalysis has played a central role in the development of efficient chemical processes for the conversion of fossil resources to fuels and chemicals, and identification of new, sustainable routes to upgrade renewable carbon sources that minimize the ecological footprint. More recently, unprecedented advances in electronic structure theory and related computational methods have provided a major thrust to the efforts that utilize density function theory (DFT) calculations for developing fundamental atomic-level understanding of these processes, and subsequently designing new and improved catalysts. In this dissertation, a combined theoretical and experimental approach is presented to study the reaction mechanisms for the catalytic conversion of formic acid (FA) and propylene oxide on transition metals. An iterative methodology comprising of DFT calculations, reaction kinetics measurements, and mean-field microkinetic modeling is employed to determine the nature of active sites on supported catalysts, explain the experimentally observed trends, and obtain predictions for the surface environment under reaction conditions. A detailed analysis of the DFT derived thermochemistry and kinetics parameters over a wide range of transition metal surfaces is performed to identify the key reactivity descriptors for FA decomposition on transition metal catalysts, and develop semi-empirical linear correlations that are then used to develop a microkinetic modeling based framework for the identification and design of improved (active and selective) bimetallic alloy catalysts. Finally, the possible utilization and applications of these methods and ideas in other key chemical transformations are proposed, and suggestions for future work are included.
Author: Jean-Michel Savéant
Publisher: John Wiley & Sons
ISBN: 047175806X
Category : Science
Languages : en
Pages : 505
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Book Description
This book is based on the George Fisher Baker Lecture given by Jean-Michel Savéant at Cornell University in Fall 2002. * The first book focusing on molecular electrochemistry * Relates to other fields, including photochemistry and biochemistry * Outlines clearly the connection between concepts, experimental illustrations, proofs and supporting methods * Appendixes to provide rigorous demonstrations to prevent an overload of algebra in the main text * Applications-oriented, focused on analyzing the results obtained rather than the methodology
