Rational Design of Non-precious Metal Oxide Catalysts by Means of Advanced Synthetic and Promotional Routes PDF Download
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Author: Michalis Konsolakis
Publisher: Mdpi AG
ISBN: 9783036561646
Category : Science
Languages : en
Pages : 0
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Book Description
This reprinted edition of the Special Issue entitled "Rational Design of Non-Precious Metal Oxide Catalysts by Means of Advanced Synthetic and Promotional Routes" covers some of the recent advances in relation to the fabrication and fine-tuning of metal oxide catalysts by means of advanced synthetic and/or promotional routes. It consists of fourteen high-quality papers on various aspects of catalysis, related to the rational design and fine-tuning strategies during some of the most relevant applications in heterogeneous catalysis, such as N2O decomposition, the dry reforming of methane (DRM), methane combustion and partial oxidation, and selective catalytic reduction (SCR), among others.
Author: Michalis Konsolakis
Publisher: Mdpi AG
ISBN: 9783036561646
Category : Science
Languages : en
Pages : 0
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Book Description
This reprinted edition of the Special Issue entitled "Rational Design of Non-Precious Metal Oxide Catalysts by Means of Advanced Synthetic and Promotional Routes" covers some of the recent advances in relation to the fabrication and fine-tuning of metal oxide catalysts by means of advanced synthetic and/or promotional routes. It consists of fourteen high-quality papers on various aspects of catalysis, related to the rational design and fine-tuning strategies during some of the most relevant applications in heterogeneous catalysis, such as N2O decomposition, the dry reforming of methane (DRM), methane combustion and partial oxidation, and selective catalytic reduction (SCR), among others.
Author: Zhuang Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
ABSTRACT OF THE DISSERTATION Rational Design of Transition Metal-Nitrogen-Carbon Electrocatalysts for Oxygen Reduction Reaction by Zhuang Liu Doctor of Philosophy in Chemical Engineering University of California, Los Angeles, 2018 Professor Yunfeng Lu, Chair The harvest and conversion of energy is of crucial importance for human civilization. Today, the fast growth in energy consumption, together with the environmental problems caused by fossil fuel usage, calls for renewable and clean energy supply, such as solar, wind, geothermal, and tidal energy. However, such energies are not consistent in both time and location, bringing energy storage on request. Intensive research has been focused on the development of electrochemical energy storage (EES) devices. Among these EES devices, hydrogen fuel cells and metal-air batteries have attracted the special attention because of their high theoretical energy densities. Yet, one major issue lies in the sluggish oxygen reduction reaction (ORR) that takes place at the cathodes. For example, the theoretical voltage of a hydrogen-oxygen fuel cell is 1.23 V (standard condition). However, the voltage output obtained under a meaningful current density is only about 0.7 V, where the voltage loss is primarily caused by the overpotential in the cathodes. Developing efficient electro-catalysts, which can lower the overpotential of ORR, is indispensable for achieving high performance devices. The state-of-the-art ORR electro-catalysts are generally based on platinum, which is limited by cost and scarcity. Developing electro-catalysts based on earth abundant metal elements is critical for large-scale application of fuel cells and metal-air batteries. Among the non-precious-metal catalysts (NPMCs) explored in recent decades, pyrolyzed iron-nitrogen-carbon (Fe-N-C) catalysts is widely regarded as the most promising candidate for replacing platinum due to their high activity. However, the traditional method for preparing Fe-N-C catalysts involves high-temperature pyrolysis of the precursors, which is a highly complex and unpredictable process. As-prepared Fe-N-C catalysts usually contain mixed chemical phases (e.g., Fe-based nanoparticles, Fe-N coordination site and various nitrogen species), as well as carbon scaffolds with random morphology. Such complexity makes it difficult to identify the active site and control the porous structure. Though progress has been made in improving their performance through delicate selection of precursors, such process is largely based on test-and-trial method, shedding little light on the understanding of the material. In this dissertation, we designed a novel "post iron decoration" synthetic strategy towards efficient Fe-N-C catalysts, which de-convolutes the growth of iron and nitrogen species, enables the rational design of the catalyst structure, and provides a series of effective model materials for active site probing. Specifically, liquid iron penta-carbonyl was used to wet the surface of mesoporous N-doped carbon spheres (NMC), whose porous structure is determined by the template used for preparation. The obtained Fe(CO)5/NMC complex was then pyrolyzed to generate the Fe/NMC catalysts. Through comparative study and thorough material characterization, we demonstrated that the pyridinic-N of NMC anchors the Fe atoms to form Fe-Nx active sites during pyrolysis, while the graphitic-N remains ORR active. The excessive Fe atoms were aggregated forming fine nanoparticles, which were subsequently oxidized forming amorphous-iron oxide/iron crystal core-shell structure. All the composing elements of Fe/NMC catalysts are uniformly distributed on the NMC scaffold, whose porous structure is shown to be not affected by Fe decoration, guaranteeing the effective exposure of active sites. The best performing Fe/NMC catalysts exhibited a high half-wave potential of 0.862 V, which is close to that of the benchmark 40% Pt/C catalyst. Such high activity is primarily attributed to the Fe-Nx active sites in the catalysts. While the surface oxidized Fe crystallites though not being the major active site, is revealed to catalyze the reduction of HO2-, the 2e ORR product, facilitating the 4e reduction of oxygen. Finally, such synthetic strategy is successfully extended to prepare other Me-N-C materials. Based on the established understanding of the active sites, we then complexed the active Fe(CO)5 molecules with a N-rich metal-organic framework (ZIF-8) to form a precursor, which was subsequently pyrolyzed to form Fe-NC catalysts. During the pyrolysis, Fe(CO)5 reacts homogeneously with the ZIF-8 scaffold, leading to the formation of uniform distribution of Fe-related active sites on the N-rich porous carbon derived from ZIF-8. The zinc atoms in the crystalline structure of ZIF-8 serves as thermo-sacrificial template, resulting in the formation of hierarchical pores that provide abundant easily accessible ORR active sites. In virtue of these advantageous features, the best performing Fe-NC catalyst exhibited a high half-wave potential of 0.91 V in rotating disk electrode experiment in 0.1 M NaOH. Furthermore, zinc-air battery constructed with Fe-NC-900-M as the cathode catalyst exhibited high open-circuit voltage (1.5 V) and a peak power density of 271 mW cm-2, which outperforms those made with 40% Pt/C catalyst (1.48 V, 1.19 V and 242 mW cm-2), and most noble-metal free ORR catalysts reported so far. Finally, such a synthetic method is economic and easily-scalable, offering possibility for further activity and durability improvement.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
The rational design and understanding of supported oxide catalysts requires at least three advancements, in order of increasing complexity: the ability to quantify the number and nature of active sites in a catalytic material, the ability to place external controls on the number and structure of these active sites, and the ability to assemble these active sites so as to carry out more complex functions in tandem. As part of an individual investigator research program that is integrated with the Northwestern University Institute for Catalysis in Energy Processes (ICEP) as of 2015, significant advances were achieved in these three areas. First, phosphonic acids were utilized in the quantitative assessment of the number of active and geometrically-available sites in MOx-SiO2 catalysts, including nanocrystalline composites, co-condensed materials, and grafted structures, for M=Ti, Zr, Hf, Nb, and Ta. That work built off progress in understanding supported Fe, Cu, and Co oxide catalysts from chelating and/or multinuclear precursors to maximize surface reactivity. Secondly, significant progress was made in the new area of using thin oxide overcoats containing 'nanocavities' from organic templates as a method to control the dispersion and thermal stability of subsequently deposited metal nanoparticles or other catalytic domains. Similar methods were used to control surface reactivity in SiO2-Al2O3 acid catalysts and to control reactant selectivity in Al2O3-TiO2 photocatalysts. Finally, knowledge gained from the first two areas has been combined to synthesize a tandem catalyst for hydrotreating reactions and an orthogonal tandem catalyst system where two subsequent reactions in a reaction network are independently controlled by light and heat. Overall, work carried out under this project significantly advanced the knowledge of synthesis-structure-function relationships in supported oxide catalysts for energy applications.
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: Wesley Terrence Hong
Publisher:
ISBN:
Category :
Languages : en
Pages : 160
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Book Description
Understanding and mastering the kinetics of oxygen electrocatalysis is instrumental to enabling solar fuels, fuel cells, electrolyzers, and metal-air batteries. Non-precious transition metal oxides show promise as cost-effective materials in such devices. Leveraging the wealth of solid-state physics understanding developed for this class of materials in the past few decades, new theories and strategies can be explored for designing optimal catalysts. This work presents a framework for the rational design of transition-metal perovskite oxide catalysts that can accelerate the development of highly active catalysts for more efficient energy storage and conversion systems. We describe a method for the synthesis of X-ray emission, absorption, and photoelectron spectroscopy data to experimentally determine the electronic structure of oxides on an absolute energy scale, as well as extract key electronic parameters associated with the material. Using this approach, we show that the charge-transfer energy - a parameter that captures the energy configuration of oxygen and transition-metal valence electrons - is a central descriptor capable of modifying both the oxygen evolution kinetics and mechanism. Its role in determining the absolute band energies of a catalyst can rationalize the differences in the electron-transfer and proton-transfer kinetics across oxide chemistries. Furthermore, we corroborate that the charge-transfer energy is one of the most influential parameters on the oxygen evolution reaction through a statistical analysis of a multitude of structure-activity relationships. The quantitative models generated by this analysis can then be used to rapidly screen oxide materials across a wide chemical space for highthroughput materials discovery.
Author: Zhongqi Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 392
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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: Yayun Pu
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: S. Paddison
Publisher: The Electrochemical Society
ISBN: 1607686511
Category : Science
Languages : en
Pages : 49
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Author: Andrew James Neel
Publisher:
ISBN:
Category :
Languages : en
Pages : 406
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Author: Stephanie Mavilla
Publisher:
ISBN:
Category :
Languages : en
Pages :
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