Download or read book Electrodeposited Transition Metal Oxides as Electrocatalysts for Methane Partial Oxidation written by Yu-Chao Huang and published by . This book was released on 2021 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The conversion of methane to valuable chemicals via electrochemical approaches is of great interest in the field of catalysis. Conventional catalytic processes utilize extreme conditions (high temperatures or pressures) to provide the energy required to achieve methane activation and require sophisticated heat integration networks to be economically viable. In contrast, catalytic processes via electrification or electrocatalysis offers direct routes of methane activation under ambient conditions, with lower energy requirements and simplified configurations. However, electrochemical oxidation of methane using current electrocatalysts remains challenging due to low energy efficiencies and a seemingly unavoidable trade-off between conversion and selectivity. In this regard, many research efforts have been devoted to the development of efficient and selective electrocatalysts for the activating and transformation of methane into valuable chemicals. Over the last decade, researchers have shown that composite transition metal oxides such as NiO/ZrO2 and Co3O4/ZrO2 can catalyze the electrochemical partial oxidation of methane to value-added chemicals such as methanol, ethanol, and propanol in a carbonate electrolyte. Chemical co-precipitation has been utilized predominantly for the preparation of metal oxide catalysts which involves multiple steps such as centrifugation, collection, drying, and annealing, and result in oxide materials with poor conductivity which are not amenable to electrocatalysis. In this work, a one-step electrodeposition method has been developed for the preparation of CoZrOx electrocatalysts. The electrodeposited CoZrOx material was found to be an active electrocatalyst for the partial oxidation of methane with a simple fabrication method. Furthermore, different electrodeposited unary transition metal oxides (CoOx, NiOx, MnOx, FeOx, and CuOx) were prepared through the same electrodeposition method, and were also studied for the electrochemical oxidation of methane. CoOx, NiOx, CuOx, and the CoZrOx electrocatalysts have been discovered to catalyze the conversion of methane to methanol. The preliminary results in this work demonstrate an additional approach among the available strategies for catalyst fabrication and may provide an efficient strategy of catalyst preparation for further studies of the electrochemical oxidation of methane under ambient conditions.
Download or read book Developing Methods to Inform Catalyst Design for the Electrochemical Oxidation of Methane and Alcohols written by Michael James Boyd and published by . This book was released on 2021 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the production of natural gas and agricultural biomass/energy crops increases, new efficient and sustainable technologies will be required to convert these feedstock molecules into the same fuels and chemical we get from conventional petroleum today. Electrochemistry is a possible tool for the conversion of these species that can be coupled to renewable electricity. The discovery and development of selective and active electrocatalysts is one of the primary challenges in utilizing natural gas and biomass resources. But first there is a lack of fundamental understanding in (1) the reaction mechanism and (2) how operating conditions such as potential, electrolyte pH, mass transport, and time affect the the activity and selectivity of catalysts. To this end platinum was used as a model system to study electrochemical methane oxidation at room temperature and pressure. The experimental results on platinum combined with density functional theory calculations show that methane is first thermally activated at Pt (211) like step sites, then the resulting methyl intermediate is electrochemically oxidized to CO* which is in equilibrium with the final product CO2. The equilibrium can be shifted to favor complete oxidation by adjusting the applied electrochemical potential, specifically at potentials below 0.5 V vs. RHE CO* is the most thermodynamically stable species along the reaction pathway whereas above 0.5 V vs. RHE CO2 is now the most stable species. Important to note however is that since the kinetics for methane activation are very slow (barrier of ~0.95 eV) the platinum surface must be free of other adsorbed species, namely protons or hydroxides. Based on reaction mechanism for electrochemical methane oxidation on platinum it is unlikely that partial oxidation of methane on metallic electrodes well occur. For this reason we probed the activity of several transition metal oxide materials with the hope that they may be active for methane oxidation. Unfortunately our initial results suggest no significant methane oxidation occurs on these materials. In the case of biomass oxidation 1st row transition metal oxides have recently been shown to be quite selective in the conversion of alcohols to their corresponding carboxylic acids. Benzyl alcohol was used as a model molecule to study the reaction mechanism for alcohol oxidation on Ni(OH)2 electrodes as a function of potential and electrolyte pH. It was found that the active phase for alcohol oxidation is the metal oxy-hydroxide. The activity and selectivity were found to be heavily dependent on the electrolyte pH. Under strong alkaline conditions (> pH 13) high current densities and complete oxidation of benzyl alcohol to benzoate was favored whereas at more moderately alkaline conditions low current densities and partial oxidation to benzaldehyde was favored. Based on these results we hypothesize that a significant concentration of OH- in solution is required to activated the intermediate product benzaldehyde. The activity of several novel Ni materials was also probed for benzyl alcohol oxidation. Ni-doped nitrided carbons which have single atom nickel active sites were found to be selective for partial oxidation, however further optimization of the catalyst synthesis is required to increase the activity to compete with the bulk Ni(OH)2 electrodes. In conclusion, this dissertation presents a variety of experimental work focused on identifying the reaction mechanism for several oxidation reactions and provides key understanding that can be used towards the development of new electrocatalysts for the oxidation of hydrocarbons and alcohols.
Download or read book Metal Oxides written by J.L.G. Fierro and published by CRC Press. This book was released on 2005-08-24 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemistry of metals has traditionally been more understood than that of its oxides. As catalytic applications continue to grow in a variety of disciplines, Metal Oxides: Chemistry and Applications offers a timely account of transition-metal oxides (TMO), one of the most important classes of metal oxides, in the context of catalysis. The
Download or read book Metal Oxides and Related Solids for Electrocatalytic Water Splitting written by Junlei Qi and published by Elsevier. This book was released on 2022-05-16 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxides and Related Solids for Electrocatalytic Water Splitting reviews the fundamentals and strategies needed to design and fabricate metal oxide-based electrocatalysts. After an introduction to the key properties of transition metal oxides, materials engineering methods to optimize the performance of metal-oxide based electrocatalysts are discussed. Strategies reviewed include defect engineering, interface engineering and doping engineering. Other sections cover important categories of metal-oxide (and related solids) based catalysts, including layered hydroxides, metal chalcogenides, metal phosphides, metal nitrides, metal borides, and more. Each chapter introduces important properties and material design strategies, including composite and morphology design. There is also an emphasis on cost-effective materials design and fabrication for optimized performance for electrocatalytic water splitting applications. Lastly, the book touches on recently developed in-situ characterization methods applied to observe and control the material synthesis process. Introduces metal oxide-based materials for electrocatalytic water splitting applications, including their key properties, synthesis, design and fabrication strategies Reviews the most relevant materials design strategies, including defect engineering, interface engineering, and doping engineering Discusses the pros and cons of metal oxide-based materials for water splitting applications to aid in materials selection
Download or read book Transition Metal Oxides written by H.H. Kung and published by Elsevier. This book was released on 1989-04-01 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book the author presents an up-to-date summary of existing information on the structure, electronic properties, chemistry and catalytic properties of transition metal oxides. The subjects covered in the book can be divided into three sections. The first (chapters 1 to 3) covers the structural, physical, magnetic, and electronic properties of transition metal oxides. Although the emphasis is on surface properties, relevant bulk properties are also discussed. The second section (chapters 4 to 7) covers surface chemical properties. It includes topics that describe the importance of surface coordinative unsaturation in adsorption, the formation of surface acidity and the role of acidity in determining surface chemical properties, the nature and reactivities of adsorbed oxygen, and the surface chemistry in the reduction of oxides. The third section (chapters 8 to 14) is on the catalytic properties. Various catalytic reactions including decomposition, hydrogenation, isomerization, metathesis, selective oxidation, and reactions involving carbon oxides are discussed. Emphasis is placed more on reaction mechanisms and the role of catalysts than on kinetics and processes. Chapters on the preparation of oxide catalysts and on photo-assisted processes are also included. Whenever appropriate, relationships between various topics are indicated. Written for surface physicists, chemists, and catalytic engineers, the book will serve as a useful source of information for investigators and as a comprehensive overview of the subject for graduate students.
Download or read book Partial Oxidation of Methane and Ethane Over Metal Oxide Catalysts written by Dingjun Wang and published by . This book was released on 1995 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metal Oxides Chalcogenides and Composites written by Aneeya Kumar Samantara and published by Springer. This book was released on 2019-08-09 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the recent development of metal oxides, hydroxides and their carbon composites for electrochemical oxidation of water in the production of hydrogen and oxygen as fuels. It includes a detailed discussion on synthesis methodologies for the metal oxides/hydroxides, structural/morphological characterizations, and the key parameters (Tafel plot, Turnover frequency, Faradic efficiency, overpotential, long cycle life etc.) needed to evaluate the electrocatalytic activity of the materials. Additionally, the mechanism behind the electro oxidation process is presented. Readers will find a comprehensive source on the close correlation between metal oxides, hydroxides, composites, and their properties and importance in the generation of hydrogen and oxygen from water. The depletion of fossil fuels from the earth’s crust, and related environmental issues such as climate change, demand that we search for alternative energy resources to achieve some form of sustainable future. In this regard, much scientific research has been devoted to technologies such as solar cells, wind turbines, fuel cells etc. Among them fuel cells attract much attention because of their versatility and efficiency. In fuel cells, different fuels such as hydrogen, CO2, alcohols, acids, methane, oxygen/air, etc. are used as the fuel, and catalysts are employed to produce a chemical reaction for generating electricity. Hence, it is very important to produce these fuels in an efficient, eco-friendly, and cost effective manner. The electrochemical splitting of water is an environmentally friendly process to produce hydrogen (the greener fuel used in fuel cells), but the efficiencies of these hydrogen evolution reactions (cathodic half reaction) are strongly dependent on the anodic half reaction (oxygen evolution reaction), i.e., the better the anodic half, the better will be the cathodic reaction. Further, this oxygen evolution reaction depends on the types of active electrocatalysts used. Though many more synthetic approaches have been explored and different electrocatalysts developed, oxide and hydroxide-based nanomaterials and composites (with graphene, carbon nanotubes etc.) show better performance. This may be due to the availability of more catalytic surface area and electro active centers to carry out the catalysis process.
Download or read book The Influence of Surface Structure on the Catalytic Activity of Alumina Supported Transition Metal Oxides written by Paul Worn Park and published by . This book was released on 1996 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Understanding Homogeneous and Heterogeneous Transition Metal Oxide Catalytic Systems for Partial Oxidation Reactions written by Ehsan Moharreri and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal oxide-based systems as catalysts for oxidative reactions are studied. Utilizing aerobic oxygen as a cost-efficient and benign oxidant is explored for alcohol oxidation reactions. A detailed magnetic study is performed to understand the active phases of manganese oxide catalysts. The role of a well-known homogeneous copper oxide catalyst in an oxidation reaction is explored for making alcohols from aliphatic hydrocarbons. Finally, virtual screening techniques are explored in a preliminary study for materials discovery. In chapter I, aerobic transformation of alcohols is studied by mesoporous manganese oxide and cobalt oxide species. Catalyst optimization, characterization and substrate scope experimentation is performed for self-esterification of alcohols and aldehydes. In chapter II, a comprehensive magnetic characterization of mesoporous manganese oxide species is provided. While conventional methods do not lead to definitive phase determination, magnetic transitions and spin eco NMR techniques prove the mixed phase of meso MnOx materials. In chapter III, a synthetic copper complex is studied. The complex was modeled after the active site of particulate methane monooxygenase (pMMO). A detailed study of the complex structure, reaction medium and by- products showed that an important side reaction interfered with hydrocarbon oxidation. The nitrile solvent decomposes to amide by nucleophilic interactions from hydrogen peroxide. In the final chapter, preliminary computational screening tools are introduced. Extraction of geometrical features of molecular structures and evaluation of total energy with machine learning algorithms are performed and the ground work for application of such work to crystalline materials is proposed.
Download or read book Physical Electrochemistry written by Noam Eliaz and published by John Wiley & Sons. This book was released on 2019-01-04 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This bestselling textbook on physical electrochemistry caters to the needs of advanced undergraduate and postgraduate students of chemistry, materials engineering, mechanical engineering, and chemical engineering. It is unique in covering both the more fundamental, physical aspects as well as the application-oriented practical aspects in a balanced manner. In addition it serves as a self-study text for scientists in industry and research institutions working in related fields. The book can be divided into three parts: (i) the fundamentals of electrochemistry; (ii) the most important electrochemical measurement techniques; and (iii) applications of electrochemistry in materials science and engineering, nanoscience and nanotechnology, and industry. The second edition has been thoroughly revised, extended and updated to reflect the state-of-the-art in the field, for example, electrochemical printing, batteries, fuels cells, supercapacitors, and hydrogen storage.
Download or read book Transition Metal Doped Rare earth Metal Oxide Catalysts for Dry Reforming of Methane written by Bo Li and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dry reforming of methane (DRM) is an environment-friendly and sustainable chemical technique, since it converts methane and CO2, two most abundant greenhouse gases, into syngas and other high value chemical products. The most common catalyst for DRM reaction is Ni due to its low cost and high catalytic activity but Ni-based catalysts undergo severe deactivation due to coking. transition metal (TM) doped rare earth oxide catalysts have shown promise in the high catalytic activity and coking resistance ability. This thesis applies the first principles calculation method to design Ni and Zr doped CeO2 catalyst model. Density functional theory (DFT+U) method is used to generate the structure-composition-stability relationships. The distribution of Zr with multiple concentrations have been studied in the CeO2 fluorite lattice. The oxygen vacancy effect has also been examined in the bulk and surface Ni-doped CeO2 bulk and surface structure to determine the most stable configuration. The surface chemistry study of Ni-doped CeO2 surface shows that hydrocarbon over the surface is always oxidized and prefers bonding to the oxygen site rather than the Ni site. This result can thermodynamically explain the reason of catalyst coking resistance.
Download or read book Investigating Electronic Structure Effects in Transition Metal Oxides Used as Catalysts for Water Oxidation and CO2 Reduction written by Hongyu Shang and published by . This book was released on 2018 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: In separate studies, Fe-Ni oxide has been tested as a catalyst for electrochemical CO2 reduction. Developing efficient methods to reduce CO2 to a high-energy-density fuel or other value-added products is important to solve pressing issues related to energy conversion and storage. Developing more active catalysts to improve the slow cathode kinetics is essential to improve the conversion efficiency of CO2 reduction. Cu is the only metal showing high selectivity for C-C bond coupling during electrochemical CO2 reduction, and few studies have investigated the use of mixed metal oxides for this reaction. In our group, we have demonstrated that CuFeO2 has the ability to convert CO2 to acetate with high selectivity. To further understand this reaction, we now investigate modified catalysts where Cu has been replaced by Ni. These catalysts are prepared by the same electrodeposition method followed by thermal annealing as previously reported for CuFeO2 catalysts. XRD shows that the catalyst adopts the spinel NiFe2O4 phase compared to the delafossite phase, CuFeO2. Electrolysis is performed to study catalyst performance, and results show that Ni-Fe oxide catalysts produce a comparable or even higher acetate yield compared to CuFeO2. Further XUV spectroscopy experiments are planned to investigate how the electronic structure influences the selectivity and efficiency of the catalyst.
Download or read book Transition Metal Oxides for Electrochemical Energy Storage written by Jagjit Nanda and published by John Wiley & Sons. This book was released on 2022-03-30 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition Metal Oxides for Electrochemical Energy Storage Explore this authoritative handbook on transition metal oxides for energy storage Metal oxides have become one of the most important classes of materials in energy storage and conversion. They continue to have tremendous potential for research into new materials and devices in a wide variety of fields. Transition Metal Oxides for Electrochemical Energy Storage delivers an insightful, concise, and focused exploration of the science and applications of metal oxides in intercalation-based batteries, solid electrolytes for ionic conduction, pseudocapacitive charge storage, transport and 3D architectures and interfacial phenomena and defects. The book serves as a one-stop reference for materials researchers seeking foundational and applied knowledge of the titled material classes. Transition Metal Oxides offers readers in-depth information covering electrochemistry, morphology, and both in situ and in operando characterization. It also provides novel approaches to transition metal oxide-enabled energy storage, like interface engineering and three-dimensional nanoarchitectures. Readers will also benefit from the inclusion of: A thorough introduction to the landscape and solid-state chemistry of transition metal oxides for energy storage An exploration of electrochemical energy storage mechanisms in transition metal oxides, including intercalation, pseudocapacitance, and conversion Practical discussions of the electrochemistry of transition metal oxides, including oxide/electrolyte interfaces and energy storage in aqueous electrolytes An examination of the characterization of transition metal oxides for energy storage Perfect for materials scientists, electrochemists, inorganic chemists, and applied physicists, Transition Metal Oxides for Electrochemical Energy Storage will also earn a place in the libraries of engineers in power technology and professions working in the electrotechnical industry seeking a one-stop reference on transition metal oxides for energy storage.
Download or read book Metal Oxide Catalysis written by S. David Jackson and published by Wiley-VCH. This book was released on 2008-12-23 with total page 887 pages. Available in PDF, EPUB and Kindle. Book excerpt: With its two-volume structure, this handbook and ready reference allows for comprehensive coverage of both characterization and applications, while uniform editing throughout ensures that the structure remains consistent. The result is an up-to-date review of metal oxides in catalysis. The first volume covers a range of techniques that are used to characterize oxides, with each chapter written by an expert in the field. Volume 2 goes on to cover the use of metal oxides in catalytic reactions. For all chemists and engineers working in the field of heterogeneous catalysis.
Download or read book Methane Oxidation Over Dual Redox Catalysts written by and published by . This book was released on 1989 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to develop the scientific background for direct catalytic oxidation of methane over oxides that are doubly doped with transition metal ions. The desired process aims at employing of a double redox mechanism, where one redox couple is utilized for activation of oxygen and another for the conversion of CH3 radicals to carbocations via electron transfer reaction. The latter species can react with surface OH− groups to form methanol or formaldehyde. To establish the foundations for such a process, two groups of the catalysts, one containing dispersed redox centers (Cu{sup I}/Fe{sup III}/ZnO and Cu{sup I}/Sn{sup IV}/ZnO) and a second of delafossite-type oxides containing concentrated redox centers (CuFeO2, CuCoO2) were synthesized and chemically analyzed for composition. For the sake of comparison, undoped ZnO treated in the same way as doped zinc oxide catalysts was also prepared. The samples were characterized by X-ray diffraction, BET surface area measurements and preliminarily by scanning electron microscopy. A catalytic testing unit and reactor to study the title reaction were designed and constructed.
Download or read book Selective Methane Oxidation Over Promoted Oxide Catalysts Quarterly Report March May 1994 written by and published by . This book was released on 1994 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental work aiming at developing active catalysts for selective oxidation of methane to methanol was started in this quarter. Some of the experiments used a double catalyst bed design and with H2O as cofeed. The first catalyst bed, which serves as CH3 radical generator, was chosen to be 1 wt % SO42−/Sr/La2O3, as this catalyst exhibits remarkable activity and selectivity at lower temperature (500°C--550°C). A few transition metal oxides were used as the second catalyst bed to react with CH3 to form CH3O−M species, which was then hydrolyzed to form CH3OH. It was found that unsupported metal oxides ZrO2, Y2O3, SrO; Fe2O3, MnO2, Cr2O3, CaO, and MgO did not produce CH3OH between 430°C and 600°C when used as the only catalysts, while MoO3 supported on silica produced CH30H in the temperature range of 430°C--480°C under the current single-bed reactor configuration. However, when the double-bed configuration was used with the 1 wt % SO42−/Sr/La2O3 as the first methyl radical generating catalyst bed, CH30H was observed when ZrO2and Y2O3 were used as the second bed catalysts. Preliminary quantitative analysis showed that the ability of producing CH3OH was in the order of unsupported Y2O3> unsupported ZrO2> MoO3 on silica. For all of these cases, the CH3OH space time yield was within a dozen grams per kilogram catalyst per hour.
Download or read book Selective Methane Oxidation Over Promoted Oxide Catalysts Quarterly Report December 1 1995 February 29 1996 written by and published by . This book was released on 1996 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a systematic study with a CH4/air reactant mixture at 600 C and 0.1 MPa, it is demonstrated that among eight Cab-O-Sil supported redox transition metal oxide catalysts, a V2O5/SiO2 catalyst exhibited the highest productivities of formaldehyde and methanol. The effect of steam on enhancing the space time yields of the oxygenates was observed with the catalysts that were studied with this third component in the reaction mixture. With the vanadia-containing catalyst, it was shown that a loading of 2 wt% of V2O5 on SiO2 produced the highest conversion of methane from a CH4/air/steam = 4/1/1 reactant mixture and the highest productivities of both CH3OH and HCHO. It was also shown that increasing the reactant flow rate (thereby decreasing the contact time) increased the space time yield of methanol but decreased the overall methane conversion level.
