Transition Metal Doped Rare-earth Metal Oxide Catalysts for Dry Reforming of Methane PDF Download

Author: Bo Li
Publisher:
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Category :
Languages : en
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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.

Author: Changyi Jiang
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Category :
Languages : en
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Author: Arvind Karkal Bhat
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Category :
Languages : en
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Author: Carly Byron
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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The work outlined in this dissertation is dedicated to the surface chemistry of promoted metal nanoparticle catalysts for dry reforming of methane (DRM). The main part of this work focuses on the effect of promoters on platinum and nickel active catalysts and understanding how the change in surface chemistry affects the mechanism of the DRM reaction. We have identified several promoters that improve the DRM activity by tuning the surface chemistry; boron promoter with platinum catalyst and transition metal promoters with nickel catalyst. The addition of promoter sites led to the migration of coke deposits away from active sites, improved surface activation of CO2, and morphological control over the coke deposits. This work is necessary because growing concern over the effects of climate change has necessitated research into potential fossil fuel replacements. The current energy infrastructure already supports hydrocarbon fuel sources. However, researchers' current challenge is the ability to produce fuel in a carbon-neutral process using inexpensive catalytic materials. Heterogeneous catalysis is paramount to solving the energy problem, and the chemistry of catalytic surfaces must be optimized to achieve carbon-based fuel production that can replace fossil fuels long term. Noble metals and transition metals are highly active to hydrocarbon conversion. The dry reforming of methane (DRM) is a promising reaction because it converts methane and carbon dioxide into a "synthesis gas", or syngas, which can be processed to produce fuels and other value-added chemicals. When in the form of a nanoparticle supported on metal oxide, the active surface area of the metal is maximized, and less metal is required for catalysis. However, nanoparticle catalysts are readily deactivated by coking (carbon deposits) and sintering (nanoparticle agglomeration). Noble metals are highly active to DRM due to their high selectivity and resistance to deactivation, but they are typically too costly for practical use. Nickel is a promising DRM catalyst because of its low cost and high activity but is more susceptible to deactivation, therefore nickel is often paired with a second "promoter" metal to optimize the material and prevent deactivation. The development of active, stable bimetallic catalysts requires a detailed understanding of the chemistry at the surface during the reaction. In this work, we have identified the role of promoter sites using surface characterization techniques which provide better understanding of the catalytic mechanism.

Author: Murtadha Almousawi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Air pollution is one of the most substantial challenges of our era. It is a major contributor to climate change and a significant health hazard contributing to increased mortality or severe illness. Environmental catalysis is one of the most sustainable and effective solutions for reducing the emissions of undesirable pollutants in the atmosphere. Nonetheless, the effectiveness of pollutant removal greatly hinges upon the catalyst employed, necessitating the urgent development of exceptionally efficient catalysts. In comparison to the commonly employed precious metal catalysts, there has been a notable surge of interest in non-noble transition metal catalysts, such as copper and nickel-based catalysts. This interest is primarily due to their abundant availability, lower cost, and their considerable activities in environmental related reactions that are comparable to those of noble metal catalysts. However, there is still a pressing need to significantly enhance their low-temperature activity to meet application requirements. Increasing the metal dispersion to create more active sites and establishing a strong interaction between metals and supports are effective strategies to improve the catalytic performance of supported metal catalysts. However, achieving these improvements using simple and scalable preparation methods has posed a considerable challenge in the material science and environmental catalysis field. In this work, using hydroxyl-rich (OH-rich) CeO2 and ZrO2 as supports and a facile incipient wetness impregnation (IWI) method, we report the successful preparation of three sets of catalysts, including CuO/CeO2, CuO/ZrO2, and Ni/CeO2, with high metal dispersion and enhanced metal-support interactions. Our findings show that these catalysts prepared using OH-rich supports exhibited superior catalytic performance in environmental-related reactions, including CO oxidation, NO reduction by CO, selective catalytic oxidation of NH3 (NH3-SCO), and dry reforming of methane (DRM), respectively. Using various experimental techniques, including X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), N2 physisorption, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), the effect of hydroxyls on Ce(OH)x and Zr(OH)x supports on the physicochemical properties of the catalysts was characterized in detail. Additionally, the structure-activity relationship and reaction mechanism on these newly developed catalysts were revealed. This study showcases the utilization of OH-rich supports to improve metal dispersion and strengthen the metal-support interaction, thereby improving the catalytic performance of supported transition metal catalysts. This research suggests that utilizing OH-rich supports holds great promise as an approach to designing highly efficient catalysts for important environmental catalysis applications.

Author: Dushyant Shekhawat
Publisher: Elsevier
ISBN: 0444535640
Category : Technology & Engineering
Languages : en
Pages : 569

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Fuel Cells: Technologies for Fuel Processing provides an overview of the most important aspects of fuel reforming to the generally interested reader, researcher, technologist, teacher, student, or engineer. The topics covered include all aspects of fuel reforming: fundamental chemistry, different modes of reforming, catalysts, catalyst deactivation, fuel desulfurization, reaction engineering, novel reforming concepts, thermodynamics, heat and mass transfer issues, system design, and recent research and development. While no attempt is made to describe the fuel cell itself, there is sufficient description of the fuel cell to show how it affects the fuel reformer. By focusing on the fundamentals, this book aims to be a source of information now and in the future. By avoiding time-sensitive information/analysis (e.g., economics) it serves as a single source of information for scientists and engineers in fuel processing technology. The material is presented in such a way that this book will serve as a reference for graduate level courses, fuel cell developers, and fuel cell researchers. - Chapters written by experts in each area - Extensive bibliography supporting each chapter - Detailed index - Up-to-date diagrams and full colour illustrations

Author: Wenqiao Song
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages :

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Nowadays, environmental concerns and the global energy crisis have become two of our greatest challenges. The main purpose of this dissertation research is to design highly active mesoporous materials that can efficiently catalyze environmental and energy related reactions. Surface properties can be easily tuned by thermal treatment and cation doping, resulting in improved catalytic activities. Synthesis and characterization of the materials, catalytic activities for carbon monoxide oxidation, oxygen reduction and oxygen evolution reactions, and mechanistic studies are covered in this thesis. The first part describes the synthesis of mesoporous cobalt oxides through an inverse micelle route for low temperature carbon monoxide oxidation applications. The prepared material showed much better activity and stability compared with commercial cobalt oxide due to its nanoparticle nature and porous structure. The catalytic performance under both dry and moisture rich conditions were tested. Detailed characterization of the materials suggested that high surface areas and the presence of surface oxygen vacancies were critical for enhanced activities. In real systems, structured catalysts such as monolithic substrates coated with a layer of active material are used instead of powder form catalysts. To evaluate the potential of our catalysts to be used in practical catalytic devices, mesoporous metal oxides (MnOx, Co3O4, CeO2) were coated on cordierite substrate by dip coating and in-situ growth and were used as low temperature diesel oxidation catalysts. The resulting materials showed promising catalytic performance. The effect of particle size, loading amount and Cu doping on the catalytic performance are discussed in detail. In the last part, mesoporous cobalt oxides were used as bifunctional catalysts for oxygen reduction and oxygen evolution reactions. If a catalyst can catalyze both reactions, it will have great potential in the application of rechargeable metal air batteries. Ni and Mn doping were introduced into the cobalt oxide material to increase the conductivity and active site population. The Ni incorporated cobalt oxide exhibited the best activity, which can be considered as a potential substituent for precious metal catalysts (Pt, Ir, Ru). Furthermore, the intrinsic structure-property relationships of the materials were established.

Author: Ravneet Bhullar
Publisher:
ISBN:
Category :
Languages : en
Pages : 167

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Fossil fuels constitute 86% of global energy consumption. Even though fossil fuels have satisfied our energy needs for decades, they are non-renewable source of energy, and burning of fossil fuels is detrimental for the environment. Mining and extraction release toxic and heavy metals in the environment. The burning of fossil fuels release greenhouse carbon dioxide, SO2, NOX and volatile organic compounds into the atmosphere. Hence, the development of non-fossil fuel based alternative sources of energy is a logical solution to address these concerns. This thesis work primarily focused on design, development and understanding the chemistry of two-dimensional (2D) layered materials, particularly transition metal oxides, birnessite and lithium cobalt oxide as catalytic materials for the conversion of renewable energy into fuels and. In order to accomplish this, we principally studied the energy intensive oxygen evolution reaction (OER) in water splitting, and Fischer-Tropsch synthesis (FTS) to generate synthetic fuels. Birnessite is a 2D layered manganese dioxide material with intercalated Lewis cations and water molecules. Birnessites have been extensively investigated for their catalytic activity towards oxygen evolution reaction. In this work, we studied the influence of interstitial hydration structure on the catalytic efficiency of birnessite towards OER. The results of this study facilitated the development of upgraded, low-cost and, earth abundant catalyst for the OER. We demonstrated that the layered materials constructed from the same batch of nanosheets, but with different interlayer hydration structure exhibited significant differences in catalytic activity for chemical and electrochemical water oxidation. The dominant factor in these differences was the enhancement of relevant water fluctuations due to geometric frustration leading to enhanced electron transfer rate in the oxidation step of water splitting. Furthermore, lithium cobalt oxide (LiCoO2) and Co-doped birnessite were explored for their competence as precatalysts for Fischer-Tropsch synthesis (FTS). FTS is a commercial technology that allows converting synthesis gas, a mixture of CO and H2, into fuels and chemicals. This process is fundamentally important in the reduction of fossil fuel dependency for the energy needs. It has a great potential for generating synthetic fuels from renewable sources, such as biomass, after its gasification into synthesis gas. The synthetic fuels produced via this technology have a lower local environmental impact as compared to the conventional fuel, since it is practically free of sulfur and nitrogen impurities and yields lower exhaust emissions of hydrocarbons. The present study focused on the use of cobalt-based catalysts for the production of small to medium chain hydrocarbons (paraffins and olefins). In particular, the correlation between product selectivity and varying catalyst properties and reaction parameters was studied. In-situ studies revealed that LiCoO2 was reduced to metastable Co(hcp) and Co(fcc) nanoparticles during the activation process, providing a high surface area medium for the adsorption and hydrogenation of CO. The catalyst exhibited a high %CO conversion with small to medium chain hydrocarbon products (C2-C7). Co-doped birnessited was reduced to Co(hcp) and MnO(ccp) phases during the activation step of the FTS reaction. MnO provided an excellent medium for the dispersion and stabilization of the cobalt nanoparticles to catalyze CO-hydrogenation. Lower olefins and paraffins (C2-C4) were selectively synthesized in conjunction with low CO2 production and methane selectivity. These studies suggested that transition metal oxide based layered heterogeneous catalysts are capable of producing chemicals and fuels directly from H2-rich synthesis gas. This gas-to-chemicals process can greatly reduce CO2 emissions, thereby contributing to the mitigation of climate change and the energy needs of the future generations.

Author: Catherine Azzaro-Pantel
Publisher: Academic Press
ISBN: 0128111984
Category : Technology & Engineering
Languages : en
Pages : 590

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Design, Deployment and Operation of a Hydrogen Supply Chain introduces current energy system and the challenges that may hinder the large-scale adoption of hydrogen as an energy carrier. It covers the different aspects of a methodological framework for designing a HSC, including production, storage, transportation and infrastructure. Each technology's advantages and drawbacks are evaluated, including their technology readiness level (TRL). The multiple applications of hydrogen for energy are presented, including use in fuel cells, combustion engines, as an alternative to natural gas and power to gas. Through analysis and forecasting, the authors explore deployment scenarios, considering the dynamic aspect of HSCs. In addition, the book proposes methods and tools that can be selected for a multi-criteria optimal design, including performance drivers and economic, environmental and societal metrics. Due to its systems-based approach, this book is ideal for engineering professionals, researchers and graduate students in the field of energy systems, energy supply and management, process systems and even policymakers. - Explores the key drivers of hydrogen supply chain design and performance evaluation, including production and storage facilities, transportation, information, sourcing, pricing and sustainability - Presents multi-criteria tools for the optimization of hydrogen supply chains and their integration in the overall energy system - Examines the available technology, their strengths and weaknesses, and their technology readiness levels (TRL), to draw future perspectives of hydrogen markets and propose deployment scenarios - Includes international case studies of hydrogen supply chains at various scales

Author: Inamuddin
Publisher: Springer Nature
ISBN: 3030728773
Category : Science
Languages : en
Pages : 354

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This edited book provides an in-depth overview of carbon dioxide (CO2) transformations to sustainable power technologies. It also discusses the wide scope of issues in engineering avenues, key designs, device fabrication, characterizations, various types of conversions and related topics. It includes studies focusing on the applications in catalysis, energy conversion and conversion technologies, etc. This is a unique reference guide, and one of the detailed works is on this technology. The book is the result of commitments by leading researchers from various backgrounds and expertise. The book is well structured and is an essential resource for scientists, undergraduate, postgraduate students, faculty, R&D professionals, energy chemists and industrial experts.