Author: Luis M. AparicioPublisher:
ISBN:
Category :
Languages : en
Pages : 678
Book Description
Transition Metal-exchanged Zeolites as Catalysts for Redox Reactions
Author: Luis M. AparicioExploring Scaling Relations for Chemisorption Energies on Transition-metal-exchanged Zeolites ZSM-22 and ZSM-5
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 6
Book Description
Copper exchange on all the different T sites of ZSM-22 and ZSM-5 is considered and the chemisorption energies of dioxygen, OH, and O species are studied. We show that for different T sites the adsorption energies vary significantly. The oxygen adsorption energy on copper-exchanged zeolites is quite similar to those of the most selective catalysts for oxidation reactions, that is, Ag and Au surfaces. The chemisorption energies of oxygen, carbon-, and nitrogen-containing species on different transition metals exchanged in ZSM-22 are also investigated. The study covers three different oxidation states, that is, 1+, 2+, and 3+ for the transition-metal exchanges. Scaling relations are presented for the corresponding species. Lastly, chemisorption of O scales with chemisorption of OH for all three considered exchanges, whereas there are essentially rough correlations for NH2 and N as well as CH3 and C.
Selective Oxidation of Olefins Over Transition Metal-exchanged Zeolite Y
Author: Pei-Shing DaiPublisher:
ISBN:
Category : Hydrocarbons
Languages : en
Pages : 312
Book Description
Catalysis by Unique Metal Ion Structures in Solid Matrices
Author: Gabriele CentiPublisher: Springer Science & Business Media
ISBN: 9401007829
Category : Science
Languages : en
Pages : 331
Book Description
Atomically dispersed metal cations and small polyatomic cationic structures co-ordinated to the surface of porous matrices exhibit different properties from the same cationic species contained in a bulk oxide or supported on amorphous carriers. This subject is treated to an extensive review, showing how an understanding of it is essential to the development of a new generation of solid catalysts. There are also exciting opportunities to shape the catalytic properties of the transition metal cations in microporous and mesoporous matrices. The book covers both theoretical and experimental aspects, including the distribution of framework Al atoms in Si-rich zeolites, distribution and siting of charge-exchanged metal cations, electronic, adsorptive and catalytic properties of metal cations, and correlation of metal cation structure and siting with catalytic activity.
Catalytic Oxidation by Transition Metal Ions in Zeolites
Author: J. H. LunsfordPublisher:
ISBN:
Category :
Languages : en
Pages : 9
Book Description
The regular cavities within zeolite form a unique environment for carrying out both stoichiometric and catalytic oxidation reactions. Transition metal ions such as molybdenum and cobalt may be introduced into zeolites, where they form complexes with oxidants and substrate ligands. The objectives of the research were (a) to understand oxidation reactions in zeolites at a molecular level and (b) to evaluate the potential of zeolites as catalysts in selective oxidation reactions.
Zeolites: A Refined Tool for Designing Catalytic Sites
Author: L. BonneviotPublisher: Elsevier
ISBN: 008054469X
Category : Technology & Engineering
Languages : en
Pages : 585
Book Description
Formerly, the catalytic use of zeolites was exclusive to the field of acid catalysis. Nowadays, zeolites also find applications as catalysts in a wide array of chemical reactions such as; base catalyzed reactions, Redox reactions and catalytic reactions on transition metals and their complexes in confined environments. The concepts of Brønsted or Lewis acid-base pairs are adequately illustrated in the literature and well-understood in terms of structural and electronic properties of zeolites. By contrast, properties of chemically modified silicates, aluminosilicates and aluminophosphates have not yet been fully explored. The list of oxydo-reduction reactions performed in the presence of these new materials is growing as demonstrated by the selective catalytic reduction of nitrogen oxides or the numerous oxidations employing hydrogen peroxide. Much effort is currently being made to get a better insight into the nature of the sites involved. The zeolite lattice may also be used as a host for encapsulated complexes or metallic clusters allowing the control of nuclearity of these active species and the steric constraints imposed on the reactants. Molecular sieve and shape selectivity effects have also constituted fascinating aspects of zeolite properties. Recent developments leading to increasingly large pore sizes with VPI-5, cloverite and more recently mesoporous molecular sieves have broadened the spectrum of these applications. Indeed, larger and larger reactant and product molecules can be accommodated in these lattices. These new adsorbant/adsorbate systems create additional needs for experimental data and theoretical descriptions of transport properties, in particular of mono- and multi-components diffusion coefficients in the zeolite pore lattice. All these themes, representing the forefront and current trends in zeolite research, were discussed in the submitted papers to the symposium and are widely represented in the selected papers contained in this volume. A feature common to most of these contributions is the combined use of a variety of analytical techniques. Some of these techniques are at the frontier of the latest analytical developments such as multiple scattering EXAFS and bidimensional MAS-NMR.
Catalysis of Reactions of Oxidation by Zeolites Containing Cations of Transition Metals
Author: O. V. AltshulerPublisher:
ISBN:
Category :
Languages : en
Pages : 24
Book Description
The authors have investigated the catalytic activity of Y-type zeolite, containing cations of transition metals of the IV period - Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Cr(3+), and also Ag(+). As reactions for comparing the catalytic activity of zeolites they selected the reactions of hydrogen, carbon monoxide, ammonia, and ethylene oxidation.
Structure and Reactivity of Metals in Zeolite Materials
Author: Joaquín Pérez ParientePublisher: Springer
ISBN: 3319989057
Category : Science
Languages : en
Pages : 316
Book Description
This volume provides the reader with the most up-to-date and relevant knowledge on the reactivity of metals located in zeolite materials, either in framework or extra-framework positions, and the way it is connected with the nature of the chemical environment provided by the host. Since the first report of the isomorphous substitution of titanium in the framework of zeolites giving rise to materials with unusual catalytic properties, the incorporation of many other metals have been investigated with the aim for developing catalysts with improved performance in different reactions. The continuous expansion of the field, both in the variety of metals and zeolite structures, has been accompanied by an increasing focus on the relationship between the reactivity of metal centers and their unique chemical environment. The concepts covered in this volume are of interest to people working in the field of inorganic and physical chemistry, catalysis and chemical engineering, but also for those more interested in theoretical approaches to chemical reactivity. In particular the volume is useful to postgraduate students conducting research in the design, synthesis and catalytic performance of metal-containing zeolites in both academic and application contexts.
Catalysis by Transition-metal Ion-exchanged Zeolites
Author: T. A. DawoodRedox-based Catalytic Chemistry of Transition Metal Complexes
Author: Takahiko KojimaPublisher: Royal Society of Chemistry
ISBN: 183767647X
Category : Science
Languages : en
Pages : 0
Book Description
Transition metal complexes as catalysts play an indispensable role in transformation of chemical substances to value-added products using less energy-consuming processes and with high selectivity and efficiency. In collaboration with the Japan Society of Coordination Chemistry (JSCC), the work is a translation of the original Japanese book focusing on metal complex catalysts that are effective in redox reactions and covers important reactions involving metal complex catalysts. It describes not only what reactions proceed, but also the intermediates they pass through and how the reactions proceed, including computational chemistry approaches. It allows you to gain a deeper understanding of the reaction mechanisms of metal complex catalysts. The scope of this book includes oxidative reactions performed by high-valent metal-oxo species, reductive reactions, bond activation and bond formation, and photocatalytic reactions. Topics in this book will be interest to those studying catalytic chemistry and related fields including coordination chemistry, organometallic chemistry, organic chemistry, bioinorganic chemistry and industrial chemistry.