Download or read book Stable Complete Methane Oxidation Over Rationally Designed Pd Zeolite Catalysts for Emission Control of Natural Gas Engines written by Andrey Valentinovich Petrov and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deactivation Studies of Noble Metal Catalysts for Lean Methane Combustion written by Georgeta M. Istratescu and published by . This book was released on 2014 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: Green House Gases (GHG) contribution to global warming has led to extensive research into reduction of emission of the GHG. Transportation, as a main contributor to GHG, faces a major challenge in researching and developing of new technologies with the aim of reducing the carbon foot print. The use of alternative fuels with lower harmful emissions became obvious as a result of emission control regulations and climate change. Natural gas engines gained popularity due to their ability to burn the fuel almost completely, which recommends them as an environmentally friendly alternative to fossil fuels engines. However, the incomplete combustion of methane in natural gas engines will release methane and carbon monoxide into the atmosphere. The fugitive methane emission problem can be tackled by the development of performant catalytic converters. This project reports on catalytic activity and stability of three sets of catalyst. The first set, palladium only catalysts provided by 15, 80 and 150 g/ft3 loading, were designed for methane combustion but not necessarily for lean burn engines. The second set studied were 2 catalysts: Pt and Pt-Pd (4:1) catalyst, with a loading of 95 g/ft3. Their mainly intend was the use as diesel oxidation catalysts. The third set of catalytic converters was designed for use for lean burn gas engines. The catalysts studied were Pt-Pd (1:5) with a loading of 150 g/ft3, Pd 122 (122 g/ft3), Pd Rh (117.15:2.85) (loading 120 g/ft3) and PtPdRh (19:73:2.85) with a loading of 94.85 g/ft3. The influence of different pretreatments on the catalyst activity (i.e. de-greening temperature, reduction process) were studied through ignition-extinction experiments. The stability of the catalyst was investigated through thermal ageing experiments. The effect of water on the catalytic activity was investigated through hydro-thermal ageing experiments.

Download or read book Complete Methane Oxidation Over Alumina and Zeolite Supported Palladium for Emission Control written by and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Colloidal Design of Active Selective and Stable Catalysts for Methane Utilization written by Emmett Daniel Goodman and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to recent advances in locating and extracting natural gas resources, scientists in academia and industry are looking for new processes to take advantage of methane as a chemical precursor and fuel. However, there remain significant challenges in methane utilization; these are related to the strength of methane's carbon-hydrogen bonds, which makes this molecule difficult to activate and utilize. Without a catalyst, methane activation necessitates very high temperatures (~1000 oC), which lead to high energy costs, advanced infrastructure, toxic by-products, and poor product selectivity. Our work focuses on developing catalysts with well-defined structural properties to understand what makes materials active, selective, and stable for methane transformations. To understand which specific nanostructures are best for methane activation, size- and composition- controlled Pt/Pd nanocrystals were designed and studied to reveal the effect of catalyst structure on methane activation. Here, we discuss the effect of these unexplored parameters on methane activation rates, resistance to common catalytic poisons, and changes in oxidation state -- each of which has an important role in contributing to low-temperature activity. Perhaps the greatest challenge in methane activation is selective product formation. In this area, we studied how tuning catalyst support can help selectively produce valuable products (synthesis gas) rather than typical combustion products (carbon dioxide and water). Additionally, we started looking at even more unique nanostructures, involving both organic and inorganic components, for selective methane transformations. The high temperatures needed to activate methane require stable catalysts. By taking advantage of modular colloidal catalyst assembly, we demonstrated synthetic approaches to tune, and measure, the spatial properties of nanocrystal active sites. We found that in many conditions, the spatial properties of active sites determined catalyst stability. In Pd/Al2O3 materials we observed that closer nanocrystals are more stable, in a distant-dependent degradation process. However, in Pd/SiO2 materials we found the opposite - that stability properties are largely distant-independent. Overall, by developing colloidal approaches to catalyst synthesis, we created well-defined catalysts with precisely-controlled sizes, compositions, and spatial properties, which have helped us uncover important design rules for active, selective, and stable methane transformations.

Download or read book Exhaust Gas After treatment of Lean operated Natural Gas Engines Over Palladium based Methane Oxidation Catalysts written by Patrick Lott and published by . This book was released on 2020* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Methane Conversion by Oxidative Processes written by Wolf and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: A reasonable case could be made that the scientific interest in catalytic oxidation was the basis for the recognition of the phenomenon of catalysis. Davy, in his attempt in 1817 to understand the science associated with the safety lamp he had invented a few years earlier, undertook a series of studies that led him to make the observation that a jet of gas, primarily methane, would cause a platinum wire to continue to glow even though the flame was extinguished and there was no visible flame. Dobereiner reported in 1823 the results of a similar investigation and observed that spongy platina would cause the ignition of a stream of hydrogen in air. Based on this observation Dobereiner invented the first lighter. His lighter employed hydrogen (generated from zinc and sulfuric acid) which passed over finely divided platinum and which ignited the gas. Thousands of these lighters were used over a number of years. Dobereiner refused to file a patent for his lighter, commenting that "I love science more than money." Davy thought the action of platinum was the result of heat while Dobereiner believed the ~ffect ~as a manifestation of electricity. Faraday became interested in the subject and published a paper on it in 1834; he concluded that the cause for this reaction was similar to other reactions.

Download or read book Catalytic Low Temperature Oxidation of Methane Into Methanol Over Copper exchanged Zeolites written by Karthik Narsimhan and published by . This book was released on 2017 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: As production of shale gas has increased greatly in the United States, the amount of stranded shale gas that is flared as carbon dioxide has become significant enough to be considered an environmental hazard and a wasted resource. The conversion of methane, the primary component of natural gas, into methanol, an easily stored liquid, is of practical interest. However, shale wells are generally inaccessible to reforming facilities, and construction of on-site, conventional methanol synthesis plants is cost prohibitive. Capital costs could be reduced by the direct conversion of methane into methanol at low temperature. Existing strategies for the partial oxidation of methane require harsh solvents, need exotic oxidizing agents, or deactivate easily. Copper-exchanged zeolites have emerged as candidates for methanol production due to high methanol selectivity (> 99%), utilization of oxygen, and low reaction temperature (423-473 K). Despite these advantages, three significant shortcomings exist: 1) the location of surface intermediates on the zeolite is not well understood; 2) methane oxidation is stoichiometric, not catalytic; 3) there are few active sites and methanol yield is low. This work addresses all three shortcomings. First, a new reaction pathway is identified for methane oxidation in copper-exchanged mordenite zeolites using tandem methane oxidation and Koch carbonylation reactions. Methoxy species migrate away from the copper active sites and adsorb onto Bronsted acid sites, signifying spillover on the zeolite surface. Second, a process is developed as the first instance of the catalytic oxidation of methane into methanol at low temperature, in the vapor phase, and using oxygen as the oxidant. A variety of commercially available copper-exchanged zeolites are shown to exhibit stable methanol production with high methanol selectivity. Third, catalytic methanol production rates and methane conversion are further improved 100- fold through the synthetic control of copper speciation in chabazite zeolites. Isolated monocopper species, directed through the one-pot synthesis of copper-exchanged chabazite zeolites, correlates with methane oxidation activity and is likely the precursor to the catalytic site. Together, these synthetic methods provide guidelines for catalyst design and further improvements in catalytic activity.

Download or read book Methane Combustion over Lanthanum based Perovskite Mixed Oxides written by Hamidreza Arandiyan and published by Springer. This book was released on 2015-04-30 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents current research into the catalytic combustion of methane using perovskite-type oxides (ABO3). Catalytic combustion has been developed as a method of promoting efficient combustion with minimum pollutant formation as compared to conventional catalytic combustion. Recent theoretical and experimental studies have recommended that noble metals supported on (ABO3) with well-ordered porous networks show promising redox properties. Three-dimensionally ordered macroporous (3DOM) materials with interpenetrated and regular mesoporous systems have recently triggered enormous research activity due to their high surface areas, large pore volumes, uniform pore sizes, low cost, environmental benignity, and good chemical stability. These are all highly relevant in terms of the utilization of natural gas in light of recent catalytic innovations and technological advances. The book is of interest to all researchers active in utilization of natural gas with novel catalysts. The research covered comes from the most important industries and research centers in the field. The book serves not only as a text for researcher into catalytic combustion of methane, 3DOM perovskite mixed oxide, but also explores the field of green technologies by experts in academia and industry. This book will appeal to those interested in research on the environmental impact of combustion, materials and catalysis.

Download or read book Octane Enhancing Zeolitic FCC Catalysts written by Julius Scherzer and published by CRC Press. This book was released on 1990-08-31 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the recent literature on a method of oomphing gasoline that has become important because of the phase-down of lead in gasoline. The treatment is comprehensive rather than specific, but details of a few selected catalysts and zeolites are provided. The classifications of high-silica Y zeo

Download or read book Methane Conversion by Oxidative Processes written by Eduardo E. Wolf and published by Springer. This book was released on 1992 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: A reasonable case could be made that the scientific interest in catalytic oxidation was the basis for the recognition of the phenomenon of catalysis. Davy, in his attempt in 1817 to understand the science associated with the safety lamp he had invented a few years earlier, undertook a series of studies that led him to make the observation that a jet of gas, primarily methane, would cause a platinum wire to continue to glow even though the flame was extinguished and there was no visible flame. Dobereiner reported in 1823 the results of a similar investigation and observed that spongy platina would cause the ignition of a stream of hydrogen in air. Based on this observation Dobereiner invented the first lighter. His lighter employed hydrogen (generated from zinc and sulfuric acid) which passed over finely divided platinum and which ignited the gas. Thousands of these lighters were used over a number of years. Dobereiner refused to file a patent for his lighter, commenting that "I love science more than money." Davy thought the action of platinum was the result of heat while Dobereiner believed the ~ffect ~as a manifestation of electricity. Faraday became interested in the subject and published a paper on it in 1834; he concluded that the cause for this reaction was similar to other reactions.

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 Complete Oxidation of Methane on Palladium Catalysts Final Report written by Fabio H. Ribeiro and published by . This book was released on 2003 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report for grant DE-FG02-00ER15026. It summarizes all the accomplishments in these 8 sections: (1) Adaptations on Existing Unit and Construction of New Unit; (2) Turnover Rate and Reaction Orders for the Complete Oxidation of Methane on a Palladium Foil in Excess Dioxygen; (3) Surface area increase on Pd foils after oxidation in excess methane; (4) UV Raman spectroscopic study of hydrogen bonding in gibbsite and bayerite between 93 and 453 K; (5) Coverage of Palladium Catalysts by Oxidized Silicon During Complete Oxidation of Methane; (6) Kinetics of Methane Oxidation under lean conditions over Pd and PdO; (7) An Explanation for the Hysteresis on the Oxidation of Methane; and (8) Structure of Pd(111) after oxidation in O{sub 2}.

Download or read book Methane Oxidation Over Palladium based Catalyst for Exhaust gas After treatment written by Andreas Gremminger and published by . This book was released on 2020* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Kinetics of Complete Methane Oxidation on Palladium Model Catalysts written by and published by . This book was released on 2004 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Direct Hydroxylation of Methane written by Kazunari Yoshizawa and published by Springer Nature. This book was released on 2020-10-29 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on theoretical and computational studies by the editor’s group on the direct hydroxylation of methane, which is one of the most challenging subjects in catalyst chemistry. These studies of more than 20 years include gas-phase reactions by transition-metal oxide ions, enzymatic reactions by two types of methane monooxygenase (soluble and particulate MMO), catalytic reactions by metal-exchanged zeolites, and methane C–H activation by metal oxide surfaces. Catalyst chemistry has been mostly empirical and based on enormous experimental efforts. The subject of the title has been tackled using the orbital interaction and computations based on extended Hückel, DFT, and band structure calculations. The strength of the theoretical studies is in the synergy between theory and experiment. Therefore, the group has close contacts with experimentalists in physical chemistry, catalyst chemistry, bioinorganic chemistry, inorganic chemistry, and surface chemistry. This resulting book will be useful for the theoretical analysis and design of catalysts.

Download or read book Low temperature Activation and Catalytic Transformation of Methane to Non CO2 Products written by Franklin Tao and published by Wiley. This book was released on 2025-01-13 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sustainably tap one of the world’s most abundant natural resources with this essential guide Methane is among our crucial natural resources, with myriad applications both domestic and industrial. Atmospheric accumulation of methane, however, is one of the major drivers of climate change. The increasingly urgent search for a sustainable world demands methods for the transformation of methane that maximize its potential as a source of energy and chemical production without a harmful effect on the atmosphere and local environment. Low-Temperature Activation and Catalytic Transformation of Methane to Non-CO2 Products introduces a growing field in chemistry, chemical engineering, and energy sciences. Beginning with an overview of methane formation and its significance in chemical production, the book surveys historical transformations of methane to value-added chemicals and explains why a low-temperature route of methane transformation is necessary and significant. It then discusses existing findings in low-temperature activation and catalytic transformation, including activations with free standing single-atom cations, free standing MO+ clusters, and broadly defined M-O clusters encapsulated in zeolite, and catalytic oxidation by molecular catalysts, metal atoms anchored in zeolites, and metal sites openly exposed on alloy nanoparticles. The book concludes with a chapter discussing current challenges and promising solutions to tackle these challenges. Low-Temperature Activation and Catalytic Transformation of Methane to Non-CO2 Products readers will also find: Coverage of concepts, perspectives, and skills required for those working in this important field in catalysis research. Exemplified experimental and computational results throughout, derived from existing research literature. Detailed discussion of low-temperature transformation methods incorporating catalysts including zeolite, gold-palladium, and many more. Low-Temperature Activation and Catalytic Transformation of Methane to Non-CO2 Products is ideal for experimentalists, researchers, scientists, and engineers working in methane transformation, heterogeneous catalysis, homogeneous catalysis, sustainable chemistry, surface science, climate change mitigation, and related fields.

Download or read book Methane Mono oxidation Electrocatalysis by Palladium and Platinum Salts written by Rebecca Soyoung Kim and published by . This book was released on 2020 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Selective oxidation of methane to methanol would enable better utilization of natural gas resources. Many homogeneous metal ions activate methane under mild conditions, but turning this reactivity into catalysis requires a viable oxidation step. Electrochemistry offers unique advantages in this regard, and this thesis demonstrates two mechanistically distinct approaches for methane functionalization electrocatalysis. Following the first approach, a novel high-valent Pd complex with exceptional methane functionalization reaction rates is electrochemically generated in fuming sulfuric acid. We present a structural model of this complex as a Pd[superscript III] dimer with a Pd–Pd bond and a 5-fold O-atom sulfate/bisulfate coordination environment at each Pd atom. We also discover, using EPR spectroscopy, a mixed-valent Pd2[superscript II][superscript III] complex in the electrochemical oxidation sequence. From these and redox potential measurements, a comprehensive thermodynamic landscape for the oxidation of Pd[superscript II] to Pd[superscript III]2 emerge for the first time, and the critical role of M–M and M–L bonding in driving the electrochemical self-assembly of Pd[superscript III]2 is exposed. Building on these structural studies, we arrive at a mechanistic model for methane functionalization by Pd[superscript III]2 that simultaneously yields methyl bisulfate (MBS) and methanesulfonic acid (MSA). Rate-limiting H atom abstraction by Pd[superscript III]2 and product bifurcation from the methyl radical intermediate is proposed based on experimentally determined rate laws and observations with radical scavengers and initiators. DFT calculations likewise support a shared outer-sphere proton-coupled electron transfer (PCET) reaction for the generation of both products. Following the second approach for methane functionalization electrocatalysis, we establish an electrochemical solution to the long-standing oxidant problem of Shilov’s Pt[superscript II] catalyst. Inner-sphere electron transfer facilitates the electrochemical oxidation of Pt[superscript II] to Pt[superscript IV] on Cl-adsorbed platinum electrodes without concomitant methanol oxidation. The favorable catalytic property of this electrode is exploited for the continuous regeneration of the Pt[superscript IV] oxidant during Pt[superscript II]-catalyzed methane functionalization. The critical Pt[superscript II]/[superscript IV] ratio is maintained via dynamic modulation of the electric current and in situ monitoring of the solution redox potential. Thereby, we show stable and sustained turnover of Shilov’s catalyst for the first time.