Computational Studies of Water Adsorption in Zeolites PDF Download
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Author:
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Languages : en
Pages : 9
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Book Description
We have performed high-level ab initio calculations using Hartree-Fock (HF) theory, Moller-Plesset perturbation theory (MP2), and density-functional theory (DFT) to study the geometry and energetics of the adsorption complex involving H2O and the Bronsted acid site in the zeolite H-ZSM-5. These calculations use aluminosilicate cluster models for the zeolite framework with as many as 28 T atoms (T=Si, Al). We included geometry optimization in the local vicinity of the acid site at the MP2 and DFT levels of theory for the smallest cluster, while in the larger clusters this was done at the HF/6-31G(d) level of theory. We have also calculated corrections for zero-point energies, extensions to higher basis sets, and higher levels of electron correlation. Results for the adsorption energy and geometry of this complex are reported and compared with previous theoretical and experimental values.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
We have performed high-level ab initio calculations using Hartree-Fock (HF) theory, Moller-Plesset perturbation theory (MP2), and density-functional theory (DFT) to study the geometry and energetics of the adsorption complex involving H2O and the Bronsted acid site in the zeolite H-ZSM-5. These calculations use aluminosilicate cluster models for the zeolite framework with as many as 28 T atoms (T=Si, Al). We included geometry optimization in the local vicinity of the acid site at the MP2 and DFT levels of theory for the smallest cluster, while in the larger clusters this was done at the HF/6-31G(d) level of theory. We have also calculated corrections for zero-point energies, extensions to higher basis sets, and higher levels of electron correlation. Results for the adsorption energy and geometry of this complex are reported and compared with previous theoretical and experimental values.
Author: G. Öhlmann
Publisher: Elsevier
ISBN: 0080887503
Category : Science
Languages : en
Pages : 733
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Book Description
The proceedings of ZEOCAT 90 reflect the wide-ranging aspects of the rapidly expanding field of zeolite science and technology. The invited plenary lectures given by eminent zeolite scientists summarize current knowledge and address topical areas of zeolite research, including a contribution on the use of zeolites as membranes. The field of investigations described in the submitted articles in this volume covers a wide area of problems ranging from the influence of the synthesis process on the properties to questions of acidity, adsorption, diffusion, and catalysis. Of special interest are the newly developed applications of zeolites in the synthesis of fine chemicals, the use of zeolites for sensors and solid electrolytes, and the sophisticated zeolite-based separation processes.
Author: Mark Jeremy Rice
Publisher:
ISBN:
Category :
Languages : en
Pages : 246
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Book Description
Author: L. Bonneviot
Publisher: Elsevier
ISBN: 008054469X
Category : Technology & Engineering
Languages : en
Pages : 585
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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.
Author: A. Galarneau
Publisher: Elsevier
ISBN: 008054391X
Category : Technology & Engineering
Languages : en
Pages : 525
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Book Description
The Zeolites and Mesporous Materials at the Dawn of the 21st Century Proceedings are the expression of the oral and poster communications which where presented during the 13th International Zeolite Conference (IZC). They are subdivided into 32 thematic sessions starting from the genesis of materials to their applications through their characterisation. The paper volume contains the full texts of the 5 plenary and 6 keynote lectures and informative summaries of 150 oral and 540 poster presentations. These contributions have been selected among the 903 submissions received from a total of 57 countries! In order to gather all the communications in a handy document, the full texts of oral and poster presentations are available in CD-ROM. Besides the fields of zeolite science always represented at IZC (synthesis, characterisation, catalysis, etc¿), some subjects strengthened their position (mesoporous materials, theory and modelling), new areas emerge (advanced materials, environmental and life sciences) and older ones regain interest (natural zeolites). The understanding and development of the unique properties of porous materials relies on a unique blend of multidisciplinary knowledge: material science, with the implication of organic and colloid chemistry, to prepare micro- and mesoporous materials, surface and adsorption science sustained by theory and modelling to understand the peculiar behaviour of molecules in confined systems, special branches of catalysis, physics, chemical engineering and life science to design novel applications. The gathering of these elements is at the basis of a fruitful and evolutionary zeolite science, as it is hopefully reflected by these proceedings.
Author: Daan Frenkel
Publisher: Elsevier
ISBN: 0080519989
Category : Science
Languages : en
Pages : 661
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Book Description
Understanding Molecular Simulation: From Algorithms to Applications explains the physics behind the "recipes" of molecular simulation for materials science. Computer simulators are continuously confronted with questions concerning the choice of a particular technique for a given application. A wide variety of tools exist, so the choice of technique requires a good understanding of the basic principles. More importantly, such understanding may greatly improve the efficiency of a simulation program. The implementation of simulation methods is illustrated in pseudocodes and their practical use in the case studies used in the text. Since the first edition only five years ago, the simulation world has changed significantly -- current techniques have matured and new ones have appeared. This new edition deals with these new developments; in particular, there are sections on: - Transition path sampling and diffusive barrier crossing to simulaterare events - Dissipative particle dynamic as a course-grained simulation technique - Novel schemes to compute the long-ranged forces - Hamiltonian and non-Hamiltonian dynamics in the context constant-temperature and constant-pressure molecular dynamics simulations - Multiple-time step algorithms as an alternative for constraints - Defects in solids - The pruned-enriched Rosenbluth sampling, recoil-growth, and concerted rotations for complex molecules - Parallel tempering for glassy Hamiltonians Examples are included that highlight current applications and the codes of case studies are available on the World Wide Web. Several new examples have been added since the first edition to illustrate recent applications. Questions are included in this new edition. No prior knowledge of computer simulation is assumed.
Author: Hellmut G. Karge
Publisher: Springer Science & Business Media
ISBN: 3540739661
Category : Science
Languages : en
Pages : 411
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Book Description
"Molecular Sieves - Science and Technology" covers, in a comprehensive manner, the science and technology of zeolites and all related microporous and mesoporous materials. The contributions are grouped together topically in such a way that each volume deals with a specific sub-field. Volume 7 treats fundamentals and analyses of adsorption and diffusion in zeolites including single-file diffusion. Various methods of measuring adsorption and diffusion are described and discussed.
Author: Thijs Joseph Henk Vlugt
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Author: C. Claeys
Publisher: Gulf Professional Publishing
ISBN: 0444518266
Category : Science
Languages : en
Pages : 946
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Book Description
Recent Advances in Science and Technology of Zeolites and Related Materials is a collection of oral and poster communications, presented during the 14th International Zeolite Conference (IZC). The conference was hosted by the Catalysis Society of South Africa. In the tradition of the IZC series, this Conference provides a forum for the presentation of new knowledge in the science and technology of zeolites and related materials. Papers presented cover a wide range of topics that include synthesis, structure determination, characterisation, modelling, and catalysis. This highly visual book is a must for readers looking to stay up-to-date on zeolite science. * This three-part volume provides valuable information on zeolites and related materials* Includes papers that cover topics such as structure determination, modelling and separation processes* Contains new and exciting developments in the field
Author: Lawrence J. Dunne
Publisher: Springer Science & Business Media
ISBN: 9048124816
Category : Technology & Engineering
Languages : en
Pages : 301
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Book Description
Channels of nanotubular dimensions exist in a variety of materials (examples are carbon nanotubes and the nanotubular channels of zeolites and zeotypes) and show promise for numerous applications due to their unique properties. One of their most important properties is their capacity to adsorb molecules and these may exist in a variety of phases. "Adsorption and Phase Behaviour in Nanochannels and Nanotubes" provides an excellent review of recent and current work on adsorption on nanometerials. It is an impressive collection of papers dealing with the adsorption and phase behaviour in nanoporous materials from both experimental and theoretical perspectives. "Adsorption and Phase Behaviour in Nanochannels and Nanotubes" focuses on carbon nanotubes as well as zeolites and related materials.
