Investigation and Rational Design of the Catalyst-support Interface in Redox Catalysis by Ceria PDF Download
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Author: Zhongqi Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 392
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Book Description
Investigating and controlling the catalyst-support interfacial interaction/structure and their effects on catalytic performance are crucial for optimizing the activity, selectivity, and durability of catalytic materials, as the heterogeneous catalytic reactions typically take place on the catalyst surface and/or at the interface between the catalyst and support. Ceria (CeO2), due to its remarkable redox activity, has been widely adopted as an active support material or promoter in a multitude of redox catalytic reactions and is the focus of this research. With the goal of bridging the predictable catalyst design-fundamental understanding of performance-practical application, we expect to develop uniform and well-defined CeO2 nanostructures as model supports to investigate the underlying mechanism of the catalyst-support interactions, and furthermore establish the correlation between interfacial structure and catalytically active sites. In Chapter 2, reducible CeO2 nanorods and nanocubes, as well as irreducible SiO2 nanospheres supported cobalt oxides (CoOx) catalysts were synthesized and comparatively studied to understand the effects of support morphology, surface defect, support reducibility, in addition to the CoOx-support interactions on their redox and catalytic properties. Chapter 3 focuses on exploring the role of “bimetallic catalysts-support interaction” over highly active CeO2 nanorods supported pure cobalt oxides and cobalt-based bimetallic oxides nanoparticles (Fe-Co, Ni-Co and Cu-Co). The interactions between cobalt with the second transition metals (Fe, Ni and Cu) are discussed as well. Nanoparticle agglomeration issue always exists when using wet-chemical methods to synthesize CeO2 nanomaterials, which is harmful for catalytic applications due to decreased surface area. Therefore, Chapter 4 presents a scalable and facile electrospinning process for designing novel fibrous structured CeO2 and one-pot synthesis of high-surface-area, thermally stable and low-temperature active Ru-CeO2 nanofiber catalysts. Besides, attracted by the great interest of three-dimensional (3D) nanoarray structures fabrication towards novel and high-performance catalyst design, as well as nanodevice applications, electrochemical deposition technique was adopted for fabricating CeO2 nanoarrays in Chapter 5. Processing factors on growing controllable CeO2 nanoarrays, including the current density, reaction temperature, stirring rate, anode and substrate types were comprehensively investigated. A scale-up synthetic strategy for CeO2 nanoarrays fabrication is developed. Besides, possible mechanisms for morphological evolution and growth of CeO2 nanoarrays are discussed.
Author: Zhongqi Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 392
Get Book Here
Book Description
Investigating and controlling the catalyst-support interfacial interaction/structure and their effects on catalytic performance are crucial for optimizing the activity, selectivity, and durability of catalytic materials, as the heterogeneous catalytic reactions typically take place on the catalyst surface and/or at the interface between the catalyst and support. Ceria (CeO2), due to its remarkable redox activity, has been widely adopted as an active support material or promoter in a multitude of redox catalytic reactions and is the focus of this research. With the goal of bridging the predictable catalyst design-fundamental understanding of performance-practical application, we expect to develop uniform and well-defined CeO2 nanostructures as model supports to investigate the underlying mechanism of the catalyst-support interactions, and furthermore establish the correlation between interfacial structure and catalytically active sites. In Chapter 2, reducible CeO2 nanorods and nanocubes, as well as irreducible SiO2 nanospheres supported cobalt oxides (CoOx) catalysts were synthesized and comparatively studied to understand the effects of support morphology, surface defect, support reducibility, in addition to the CoOx-support interactions on their redox and catalytic properties. Chapter 3 focuses on exploring the role of “bimetallic catalysts-support interaction” over highly active CeO2 nanorods supported pure cobalt oxides and cobalt-based bimetallic oxides nanoparticles (Fe-Co, Ni-Co and Cu-Co). The interactions between cobalt with the second transition metals (Fe, Ni and Cu) are discussed as well. Nanoparticle agglomeration issue always exists when using wet-chemical methods to synthesize CeO2 nanomaterials, which is harmful for catalytic applications due to decreased surface area. Therefore, Chapter 4 presents a scalable and facile electrospinning process for designing novel fibrous structured CeO2 and one-pot synthesis of high-surface-area, thermally stable and low-temperature active Ru-CeO2 nanofiber catalysts. Besides, attracted by the great interest of three-dimensional (3D) nanoarray structures fabrication towards novel and high-performance catalyst design, as well as nanodevice applications, electrochemical deposition technique was adopted for fabricating CeO2 nanoarrays in Chapter 5. Processing factors on growing controllable CeO2 nanoarrays, including the current density, reaction temperature, stirring rate, anode and substrate types were comprehensively investigated. A scale-up synthetic strategy for CeO2 nanoarrays fabrication is developed. Besides, possible mechanisms for morphological evolution and growth of CeO2 nanoarrays are discussed.
Author: Alessandro Trovarelli
Publisher: World Scientific
ISBN: 1848169655
Category : Science
Languages : en
Pages : 909
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Book Description
This book follows the 2002 edition of Catalysis by Ceria and Related Materials, which was the first book entirely devoted to ceria and its catalytic properties. In the ten years since the first edition a massive amount of work has been carried out in the field, and ceria has gained a prominent position in catalysis as one of the most valuable material for several applications. This second edition covers fundamental and applied aspects of the latest advances in ceria-based materials with a special focus on structural, redox and catalytic features. Special emphasis is given to nano-engineered and nano-shaped systems which are a key factor in the predictive and rational design of ceria with novel properties.In addition, the book presents recent advances in emerging and traditional large-scale applications of ceria in catalysis, such as the treatment of emissions from mobile sources (including diesel and gasoline engines). The primary readership includes catalysis and material science researchers from academy and industry and postdoctorate and graduate students in chemistry, chemical engineering and physics.
Author: Alessandro Trovarelli
Publisher: World Scientific
ISBN: 1848169647
Category : Science
Languages : en
Pages : 909
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Book Description
This book follows the 2002 edition of Catalysis by Ceria and Related Materials, which was the first book entirely devoted to ceria and its catalytic properties. In the ten years since the first edition a massive amount of work has been carried out in the field, and ceria has gained a prominent position in catalysis as one of the most valuable material for several applications. This second edition covers fundamental and applied aspects of the latest advances in ceria-based materials with a special focus on structural, redox and catalytic features. Special emphasis is given to nano-engineered and nano-shaped systems which are a key factor in the predictive and rational design of ceria with novel properties.In addition, the book presents recent advances in emerging and traditional large-scale applications of ceria in catalysis, such as the treatment of emissions from mobile sources (including diesel and gasoline engines). The primary readership includes catalysis and material science researchers from academy and industry and postdoctorate and graduate students in chemistry, chemical engineering and physics.
Author: Shyam Deo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The enhancement of catalytic activity is often attributed to special sites along a metal-oxide boundary, where an adsorbed species interacts with both the metal and the support. Indeed, such "dual" reaction sites often with emergent chemical properties have been implicated as the active sites for many chemical reactions, whether it be simpler molecular reactions such as CO oxidation and water-gas shift or far more complex reaction pathways such as de-oxygenation of multi-oxygenated reactants like furfuryl alcohol, m-cresol etc. Moreover, close connections of synthesis, characterization, kinetic testing, and computational modeling can enable researchers to tailor metal/metal-oxide catalytic systems towards such complex catalytic requirements. In this thesis, computational catalysis techniques are integrated with experimental efforts of collaborators to investigate two catalytic reactions: furfural hydrodeoxygenation (HDO) to methyl furan and CO oxidation. Experimental works motivate a series of research questions and hypotheses, towards connecting multi-component (oxide-metal) catalytic site properties to catalytic performance. In particular, Density Functional Theory (DFT) has been used in combination with experimental characterization and reactivity studies to underline the principles governing the potentials and design of multi-component catalytic systems. HDO of furfuryl alcohol was examined using a DFT model of a metal/TiO2 nanowire interface. Redox functionality of the metal oxide aids in breaking the C-O bond of the alcohol, while the metal facilitates C-H formation to the final product, 2-methylfuran. In addition to this "bifunctionality", electron transfer between the oxide and the metal alters reactivity, suggesting emergent chemical properties unique to the interface. Our DFT results were used to explain experimental observations of enhanced selectivity for TiO2-coated Pd nanoparticles. We have also successfully extended our TiO2/Pd interface model, altering the composition of this interface to develop a set of descriptors that predict optimal HDO activity at the metal oxide/metal interface. Low-temperature CO oxidation was examined over CeO2 supported single atoms, a probe for determining the synergetic roles of single metal atom catalysts (SACs) and redox active supports. The redox states involved in catalytic oxidation cycles on SACs are not well-determined and limit rational design of these catalytic systems. Experimental characterization observes only "resting states" of SACs, whereas DFT and microkinetic studies can be used to reconcile a full redox cycle. We addressed these challenges by developing a first principles microkinetic model and reconciling elementary step reaction kinetics with experimentally measured reaction orders and activation barriers. We calibrated the microkinetic model through Bayesian statistical inference approach to include the error in both DFT calculated energetics and experimental measurements in mechanism determination. This approach successfully elucidated reaction mechanisms and identified dominant reaction networks to directly match experimental reaction orders and barriers. Combining experiment and modeling, we demonstrated role of metal oxidation states with their reactivity for oxidation catalysis, indicating that the unique oxidation activity of these catalysts arises from the relatively close stability of the wide range of oxidation states achieved through synergistic interaction with metal oxides. In addition, to achieve proper active site environment over the oxide supports, a careful and controlled adsorption of ionic and/or hydrated metal precursors over the surface is essential during synthesis, therefore we also briefly examine synthesis rules for catalysts with precise control over size and uniformity in dispersion with specific potential to generate singly adsorbed metal catalysts over oxides. In short, these works combinedly demonstrate how metal/metal oxide catalytic systems can be used to improve heterogeneous catalytic activity and selectivity for important energy conversion processes, and further on, the broader perspective of active sites design along the metal and oxide boundaries for oxidation and reduction catalysis.
Author: Alessandro Trovarelli
Publisher:
ISBN: 9781848169630
Category : Science
Languages : en
Pages : 888
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Book Description
The book follows the 2002 edition of Catalysis by Ceria and Related Materials, which was the first book entirely devoted to ceria and its catalytic properties. It covers fundamental and applied aspects of the latest advances in ceria-based materials with a special focus on structural, redox and catalytic features of nano-engineered systems. In addition, it presents recent advances of traditional large-scale applications of ceria in catalysis, such as the treatment of emissions from mobile sources (including diesel and gasoline engines).
Author: Berlin James Sudduth
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 0
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Book Description
Catalysts with well-defined surfaces are used to enhance the fundamental understanding of structure-function relationships which are hard to develop with polycrystalline materials whose surfaces are a complex mixture of various facets and defects. This dissertation reports the synthesis of ceria nanoshapes, (100) dominant cubes and (111) dominant octahedra, along with grafting techniques used to improve the control of supported oxides and reduce the impact of defects. These ceria nanoshapes were used to investigate how surface structure influences acid-base properties and defects were minimized by tuning calcination conditions. The (111) facet displayed a higher density of stronger acidic sites in comparison to the (100) facet which facilitated 2-propanol dehydration to propene. The (100) facet had a similar density of basic sites but dehydrogenation to acetone was enhanced by stronger basic sites. Supported vanadium oxides are excellent catalysts for redox reactions such as methanol oxidative dehydrogenation (ODH) to produce formaldehyde. Vanadia was deposited on ceria nanocubes using traditional incipient wetness impregnation and a liquid-phase chemical grafting technique to study the influence of loading and deposition method on vanadia structure and methanol ODH activity. Both methods generated well-dispersed vanadia monomers at low loadings but, as vanadia loadings approached monolayer coverage, samples synthesized using chemical grafting showed enhanced dispersion. Bare ceria is responsible for the undesired complete oxidation of methanol to form CO and CO2 which was minimized using chemical grafting of vanadia. Smaller vanadia species expressed greater activity during methanol ODH and improved dispersion at high loadings using chemical grafting increased methanol conversion and selectivity to formaldehyde. This grafting technique was extended to depositing silica on ceria nanoshapes to selectively titrate defect sites with less redox-active material and subsequently depositing vanadia on the remaining pristine ceria facets. After silica deposition, methanol ODH catalysis was no longer governed by differences in ceria defect density and was instead consistent with surface science and theoretical studies which predict (100) to be more active than (111) due to the coordination environments of the intrinsic facets. The knowledge gained using these materials are important in enabling the rational, informed design and improvement of catalysts.
Author: James J. Spivey
Publisher: Royal Society of Chemistry
ISBN: 1782629564
Category : Science
Languages : en
Pages : 367
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Book Description
Catalysts are required for a variety of applications and industrialists and academics are increasingly challenged to find cost effective and environmentally benign catalysts to use. This volume looks at modern approaches to catalysis and reviews the extensive literature on areas such as electrochemical promotion of catalysis, biodiesel-based metals on emission control devices, deoxygenation of fatty acids and transitioning rationally designed catalytic materials to real world catalysts produced on a commercial scale.
Author: Joseph Spanjaard Elias
Publisher:
ISBN:
Category :
Languages : en
Pages : 185
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Book Description
The low-temperature and cost-effective oxidation of carbon monoxide to carbon dioxide remains a fundamental challenge in heterogeneous catalysis that would enable a diverse range of technologies for electrochemical storage and respiratory health. The development of new catalysts is often driven by high-throughput screening and many of the resulting compounds are mixed-phase, which obscures a rigorous identification of active sites and mechanisms at play for catalysis. In this thesis, the preparation of substituted ceria nanoparticles is described to bring about a fundamental understanding of the structure of the active sites, mechanism and design descriptors for CO oxidation on ceria-based catalysts. Monodisperse, single-phase nanoparticles of late first-row transition-metal-substituted ceria (MyCe1.yO2-x, M = Mn, Fe, Co, Ni and Cu) are prepared from the controlled pyrolysis of heterobimetallic precursors in amine surfactant solutions. By means of kinetic analyses, X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM), the active site for CO oxidation catalysis is identified as atomically-dispersed, square-planar M3+ and M2+ moieties substituted into the surface of the ceria lattice. The introduction of CuO does not contribute to the catalytic activity of CuyCe1.yO2-x, lending support to the hypothesis that the substituted ceria itself is responsible for the catalytic rate enhancement in mixed-phased catalysts like CuO/CeO2 Under oxygen-rich conditions, the kinetic parameters for CO oxidation are consistent with lattice oxygen from the dispersed copper sites contributing directly to the oxidation of CO in the rate-determining step. In-situ X-ray photoelectron spectroscopy (XPS) and FTIR studies indicate that adsorbed CO can be directly oxidized to CO2 in the absence of gaseous O2, while in-situ XAS confirms that electron transfer is localized to the copper sites. XAS studies demonstrate that the reversible reducibility of dispersed copper ions is a contributing factor for the special catalytic activity of CuO/CeO2 catalysts. The oxygen-ion vacancy formation energy is introduced as an activity descriptor to rationalize trends in the catalytic activities measured for MyCe1-yO2-x nanoparticles that span over three orders of magnitude. As such, the DFT-calculated vacancy formation energy serves to guide in the rational design of catalysts through computational, rather than experimental, screening of candidate compounds for CO oxidation catalysis.
Author: Zili Wu
Publisher: Academic Press
ISBN: 0128013400
Category : Technology & Engineering
Languages : en
Pages : 393
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Book Description
Catalysis by Materials with Well-Defined Structures examines the latest developments in the use of model systems in fundamental catalytic science. A team of prominent experts provides authoritative, first-hand information, helping readers better understand heterogeneous catalysis by utilizing model catalysts based on uniformly nanostructured materials. The text addresses topics and issues related to material synthesis, characterization, catalytic reactions, surface chemistry, mechanism, and theoretical modeling, and features a comprehensive review of recent advances in catalytic studies on nanomaterials with well-defined structures, including nanoshaped metals and metal oxides, nanoclusters, and single sites in the areas of heterogeneous thermal catalysis, photocatalysis, and electrocatalysis. Users will find this book to be an invaluable, authoritative source of information for both the surface scientist and the catalysis practitioner Outlines the importance of nanomaterials and their potential as catalysts Provides detailed information on synthesis and characterization of nanomaterials with well-defined structures, relating surface activity to catalytic activity Details how to establish the structure-catalysis relationship and how to reveal the surface chemistry and surface structure of catalysts Offers examples on various in situ characterization instrumental techniques Includes in-depth theoretical modeling utilizing advanced Density Functional Theory (DFT) methods
Author: Changlin Zhang
Publisher:
ISBN:
Category : Electrocatalysis
Languages : en
Pages : 237
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Book Description
To provide alternative electrocatalysts for energy conversion and storage applications, the catalysts development including materials design, synthesis and growth mechanism, electrochemical diagnose, and reaction mechanism have been investigated and analyzed. Based on the research results in this dissertation, 8 first-authored journal papers have been published/submitted or in preparation. The research results here demonstrate a generic solid-state chemistry method for mass production of platinum group metal/alloy nanoparticles with size/shape/composition control, which could be used in multiple applications such as ammonia electro oxidation, oxygen reduction reaction, hydrazine decomposition, and carbon monoxide preferential oxidations. A highly ordered mesoporous carbon-based nanostructures as non-noble metal catalysts were also studied for oxygen reduction reaction and water splitting. To better understand the surface and interface behavior of platinum alloy catalyst under realistic reaction conditions, in-situ transmission electron microscopy was applied to dynamically investigate the real-time structure evolutions. The findings here also provide insights for establishing realistic structures-properties-applications relationships for materials science, catalysis and electrochemistry.
