Evidence For The Active Phase Of Heterogeneous Catalysts Through In Situ Reaction Product Imaging And Multiscale Modeling
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Evidence For The Active Phase Of Heterogeneous Catalysts Through In Situ Reaction Product Imaging And Multiscale Modeling
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Author :
language : en
Publisher:
Release Date : 2016
Evidence For The Active Phase Of Heterogeneous Catalysts Through In Situ Reaction Product Imaging And Multiscale Modeling written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Preparation Of Catalysts Ii
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Author : G. Poncelet
language : en
Publisher: Elsevier
Release Date : 1977-12-01
Preparation Of Catalysts Ii written by G. Poncelet and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977-12-01 with Technology & Engineering categories.
Preparation of Catalysts II
Theoretical Studies In Heterogenous Catalysis
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Author :
language : en
Publisher:
Release Date : 2008
Theoretical Studies In Heterogenous Catalysis written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Traditionally, knowledge in heterogeneous catalysis has come through empirical research. Nowadays, there is a clear interest to change this since millions of dollars in products are generated every year in the chemical and petrochemical industries through catalytic processes. To obtain a fundamental knowledge of the factors that determine the activity of heterogeneous catalysts is a challenge for modern science since many of these systems are very complex in nature. In principle, when a molecule adsorbs on the surface of a heterogeneous catalyst, it can interact with a large number of bonding sites. It is known that the chemical properties of these bonding sites depend strongly on the chemical environment around them. Thus, there can be big variations in chemical reactivity when going from one region to another in the surface of a heterogeneous catalyst. A main objective is to understand how the structural and electronic properties of a surface affect the energetics for adsorption processes and the paths for dissociation and chemical reactions. In recent years, advances in instrumentation and experimental procedures have allowed a large series of detailed works on the surface chemistry of heterogeneous catalysts. In many cases, these experimental studies have shown interesting and unique phenomena. Theory is needed to unravel the basic interactions behind these phenomena and to provide a general framework for the interpretation of experimental results. Ideally, theoretical calculations based on density-functional theory have evolved to the point that one should be able to predict patterns in the activity of catalytic surfaces. As in the case of experimental techniques, no single theoretical approach is able to address the large diversity of phenomena occurring on a catalyst. Catalytic surfaces are usually modeled using either a finite cluster or a two-dimensionally periodic slab. Many articles have been published comparing the results of these two approaches. An important advantage of the cluster approach is that one can use the whole spectrum of quantum-chemical methods developed for small molecules with relatively minor modifications. On the other hand, the numerical effort involved in cluster calculations increases rather quickly with the size of the cluster. This problem does not exist when using slab models. Due to the explicit incorporation of the periodicity of the crystal lattice through the Bloch theorem, the actual dimension of a slab calculation depends only on the size of the unit cell. In practical terms, the slab approach is mainly useful for investigating the behavior of adsorbates at medium and high coverages. Very large unit cells are required at the limit of low to zero coverage, or when examining the properties and chemical behavior of isolated defect sites in a surface. In these cases, from a computational viewpoint, the cluster approach can be much more cost effective than the slab approach. Slab and cluster calculations can be performed at different levels of sophistication: semi-empirical methods, simple ab initio Hartree-Fock, ab initio post-Hartree-Fock (CI, MP2, etc), and density functional theory. Density-functional (DF) based calculations frequently give adsorption geometries with a high degree of accuracy and predict reliable trends for the energetics of adsorption reactions. This article provides a review of recent theoretical studies that deal with the behavior of novel catalysts used for hydrodesulfurization (HDS) reactions and the production of hydrogen (i.e. catalytic processes employed in the generation of clean fuels). These studies involve a strong coupling of theory and experiment. A significant fraction of the review is focused on the importance of size-effects and correlations between the electronic and chemical properties of catalytic materials. The article begins with a discussion of results for the desulfurization of thiophene on metal carbides and phosphides, systems which have the potential to become the next generation of industrial HDS catalysts. Then, systematic studies concerned with the hydrogen-evolution reaction (HER) on extended surfaces, organometallic complexes and enzymes are presented. Finally, the reasons for the high catalytic activity of Au-CeO2 and Cu-CeO2 in the production of hydrogen through the water-gas shift reaction (CO + H2O --> H2 + CO2) are analyzed. It is shown that theoretical methods are very valuable tools for helping in the rational design of heterogeneous catalysts.
Heterogeneous Catalysts
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Author : Kurt Jensen
language : en
Publisher: Nova Publishers
Release Date : 2016
Heterogeneous Catalysts written by Kurt Jensen and has been published by Nova Publishers this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Science categories.
This book provides new research on the design, applications and research insights of heterogeneous catalysts. Chapter One discusses the assembly of nanocatalytic structures by the molecular layer epitaxy method. Chapter Two presents a comprehensive review of different solid acids used for biodiesel synthesis. Chapter Three examines process optimization of refined palm oil biodiesel production using calcium methoxide obtained from quick lime as a heterogeneous catalyst. Chapter Four studies the cyclization of pseudoionone over USY zeolites.
Finite Volumes For Complex Applications X Volume 1 Elliptic And Parabolic Problems
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Author : Emmanuel Franck
language : en
Publisher: Springer Nature
Release Date : 2023-11-01
Finite Volumes For Complex Applications X Volume 1 Elliptic And Parabolic Problems written by Emmanuel Franck and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-11-01 with Mathematics categories.
This volume comprises the first part of the proceedings of the 10th International Conference on Finite Volumes for Complex Applications, FVCA, held in Strasbourg, France, during October 30 to November 3, 2023. The Finite Volume method, and several of its variants, is a spatial discretization technique for partial differential equations based on the fundamental physical principle of conservation. Recent decades have brought significant success in the theoretical understanding of the method. Many finite volume methods are also built to preserve some properties of the continuous equations, including maximum principles, dissipativity, monotone decay of the free energy, asymptotic stability, or stationary solutions. Due to these properties, finite volume methods belong to the wider class of compatible discretization methods, which preserve qualitative properties of continuous problems at the discrete level. This structural approach to the discretization of partial differential equations becomes particularly important for multiphysics and multiscale applications. In recent years, the efficient implementation of these methods in numerical software packages, more specifically to be used in supercomputers, has drawn some attention. This volume contains all invited papers, as well as the contributed papers focusing on finite volume schemes for elliptic and parabolic problems. They include structure-preserving schemes, convergence proofs, and error estimates for problems governed by elliptic and parabolic partial differential equations. The second volume is focused on finite volume methods for hyperbolic and related problems, such as methods compatible with the low Mach number limit or able to exactly preserve steady solutions, the development and analysis of high order methods, or the discretization of kinetic equations.
Computational Modelling Of Nanomaterials
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Author : Panagiotis Grammatikopoulos
language : en
Publisher: Elsevier
Release Date : 2020-09-30
Computational Modelling Of Nanomaterials written by Panagiotis Grammatikopoulos and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-09-30 with Technology & Engineering categories.
Due to their small size and their dependence on very fast phenomena, nanomaterials are ideal systems for computational modelling. This book provides an overview of various nanosystems classified by their dimensions: 0D (nanoparticles, QDs, etc.), 1D (nanowires, nanotubes), 2D (thin films, graphene, etc.), 3D (nanostructured bulk materials, devices). Fractal dimensions, such as nanoparticle agglomerates, percolating films and combinations of materials of different dimensionalities are also covered (e.g. epitaxial decoration of nanowires by nanoparticles, i.e. 0D+1D nanomaterials). For each class, the focus will be on growth, structure, and physical/chemical properties. The book presents a broad range of techniques, including density functional theory, molecular dynamics, non-equilibrium molecular dynamics, finite element modelling (FEM), numerical modelling and meso-scale modelling. The focus is on each method’s relevance and suitability for the study of materials and phenomena in the nanoscale. This book is an important resource for understanding the mechanisms behind basic properties of nanomaterials, and the major techniques for computational modelling of nanomaterials. Explores the major modelling techniques used for different classes of nanomaterial Assesses the best modelling technique to use for each different type of nanomaterials Discusses the challenges of using certain modelling techniques with specific nanomaterials
Catalysis Science Initiative
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Author :
language : en
Publisher:
Release Date : 2016
Catalysis Science Initiative written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Characterisation Of Catalysts
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Author : John Meurig Thomas
language : en
Publisher: John Wiley & Sons
Release Date : 1980
Characterisation Of Catalysts written by John Meurig Thomas and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 1980 with Science categories.
Lincoln scholar Ronald C. White, Jr., describes Lincoln as a man of integrity whose moral compass holds the key to understanding his life.
Studies Of Heterogeneous Catalyst Selectivity And Stability For Biorefining Applications
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Author :
language : en
Publisher:
Release Date : 2014
Studies Of Heterogeneous Catalyst Selectivity And Stability For Biorefining Applications written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
The conversion of raw resources into value-added end products has long underlain the importance of catalysts in economic and scientific development. In particular, the development of selective and stable heterogeneous catalysts is a challenge that continues to grow in importance as environmental, sociological, and economic concerns have motivated an interest in sustainability and the use of renewable raw materials. Within this context, biomass has been identified as the only realistic source of renewable carbon for the foreseeable future. The development of processes to utilize biomass feedstocks will require breakthroughs in fundamental understanding and practical solutions to the challenges related to selectivity and stability of the catalysts employed. Selectivity is addressed on multiple fronts. First, the selectivity for C-O bond scission reactions of a bifunctional, bimetallic RhRe/C catalyst is investigated. Using multiple techniques, the origin of Bronsted acidity in the catalyst and the role of pretreatment on the activity, selectivity, and stability are explored. In addition, reaction kinetics experiments and kinetic modeling are utilized to understand the role of chemical functional group (i.e. carboxylic acid versus formate ester) in determining the decarbonylation versus decarboxylation selectivity over a Pd/C catalyst. Finally, kinetic studies over Pd/C and Cu/gamma-Al2O3 were performed so that that may be paired with density functional theory calculations and microkinetic modeling to elucidate the elementary reaction mechanism, identify the active site, and provide a basis for future rational catalyst design. Next, the issue of catalyst stability, important in the high-temperature, liquid-phase conditions of biomass processing, is examined, and a method for stabilizing the base-metal nanoparticles of a Cu/gamma-Al2O3 catalyst using atomic layer deposition (ALD) is developed. This advancement may facilitate the development of biorefining by enabling the replacement of precious-metal catalysts (e.g. Pd, Pt, etc.) with less expensive, but previously unstable, base-metal catalysts. Using myriad techniques, the mechanisms of catalyst deactivation and stabilization of the nanoparticles by the ALD overcoat are elucidated. Finally, the use of ALD unlocks the potential for novel catalysts architectures, and the ability to physically and chemically tune the properties of the overcoat is examined with the goals of reducing catalyst deactivation and introducing bifunctional activity.
High Throughput Screening In Chemical Heterogeneous Catalysis Technologies Strategies And Applications
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Author :
language : en
Publisher:
Release Date : 2004
High Throughput Screening In Chemical Heterogeneous Catalysis Technologies Strategies And Applications written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.