Study Of Pure Silica Zeolite Nucleation And Growth From Solution

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Study of Pure-silica Zeolite Nucleation and Growth from Solution

Author : Xiang Li
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (761 download)

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Book Synopsis Study of Pure-silica Zeolite Nucleation and Growth from Solution by : Xiang Li

Download or read book Study of Pure-silica Zeolite Nucleation and Growth from Solution written by Xiang Li and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeolites are microporous crystalline materials, which are widely used in catalysis, adsorption, and ion-exchange processes. However, in most cases, the synthesis of novel zeolites as functional materials still relies on trial-and-error methods, which are time consuming and expensive. Therefore, the motivation for this thesis work is to understand the zeolite synthesis mechanismand further develop knowledge for manipulating zeolite properties and ultimately the rational design of porous materials. This work focused on formation of silicalite-1 (pure-silica ZSM-5) from basic aqueous solutions containing tetraorthosilicate (TEOS) as silica source, and tetrapropylammonium (TPA) cations as the organic structure-directing agent. The presence of silica precursor particles with size of 2-5 nm in these mixtures prior to and during hydrothermal treatments have been observed through dynamic light scattering (DLS), small-angle X-ray (SAXS) and transmission electron microscopy (TEM). However, to quantify composition and the molecular structure transformation of these silica precursor particles during zeolite synthesis is still a technical challenge. Another important yet unresolved question is how organocations interact with these nanoparticles and direct zeolite nuclei. Unlike many studies performed analyzing the inorganic phase (silica) present in synthesis mixtures, this study quantified the organocation-silica particle interaction and its ultimate effect on zeolite growth mainly through probing the behavior of the organocations. Pulsed-field gradient (PFG) NMR was used to capture the mobility change of organocations, and was complemented with scattering measurements (DLS, SAXS) on the silica nanoparticles. On the basis of the measurement results, the thermodynamic and kinetic properties of the organic-inorganic interaction were derived. Upon aging at room temperature, this interaction manifested as binding of TPA onto the silica particles due to electrostatic interactions, and such binding behavior can be well described by the Langmuir adsorption model. Upon hydrothermal treatment, a fraction of TPA adsorbed at room temperature dissociates from the growing silica nanoparticles and the corresponding desorption profiles were fitted well by the pseudo-second order kinetic model. The addition of tetramethylammonium (TMA) as "competitors" promoted TPA desorption kinetics and hindered silica nanoparticle growth due to stronger association of TMA with particles than that of TPA. Finally, the TPA adsorption strength increased via addition of monovalent salts with increasing ionic size whereas that of TMA shows an opposite trend. This suggests one potential route for tuning the organic-silica precursor particle interactions and thus possibly affecting some kinetics steps in the synthesis.

High-silica Zeolite Nucleation from Clear Solutions

Author : Chil-Hung Cheng
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (676 download)

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Book Synopsis High-silica Zeolite Nucleation from Clear Solutions by : Chil-Hung Cheng

Download or read book High-silica Zeolite Nucleation from Clear Solutions written by Chil-Hung Cheng and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the mechanism of zeolite nucleation and crystallization will enable the zeolite science community to tune zeolite properties during synthesis in order to accommodate the purposes of various applications. Thus there has been considerable research effort in "deciphering" the mechanism by studying the growth course of tetrapropylammonium (TPA)-mediated silicalite-1 using several techniques, such as dynamic light scattering (DLS), small-angle X-ray/neutron scattering (SAXS/SANS), and nuclear magnetic resonance (NMR). While these studies have generated a more comprehensive picture on the silicalite-1 growth mechanism, the general application of the mechanism and how it could be applied to other zeolite systems have not been addressed. This work initially tried to apply the insights developed from the TPA-silicalite-1 clear solution synthesis by investigating the nanoparticles formation and zeolite growth in several tetraethyl orthosilicate (TEOS)-organocation-water solutions heated at 368 K using SAXS. The results are in contrast to TEOS-TPAOH-water mixtures that rapidly form silicalite-1 at 368 K. These results imply that the developed TPA-silicalite-1 nucleation and crystallization mechanismis not universally applicable to other zeolite systems and TPA-silicalite-1 itself could be a special case. With this in mind, the next goal of this work uses in situ SAXS to revisit silicalite-1 growth kinetics prepared by using several TPA-mimic organocations and some asymmetric geometry organocations. The results clearly show the TPA cation is an extraordinarily efficient structure-directing agent (SDA) due to its moderate hydrophobicity and perfect symmetric geometry. Any perturbation of the hydrophobicity and symmetry of SDA leads to a deterioration of zeolite growth. This work further investigates the influences of alcohol identity and content on silicalite-1 growth from clear solutions at 368 K using in situ SAXS. Several tetraalkyl orthosilicates (Si(OR)4, R = Me, Pr, and Bu) are used as the alternative silica sources to TEOS in synthesizing silicalite-1. Increasing the alcohol identity hydrophobicity or lowering the alcohol content enhances silicalite-1 growth kinetics. This implies that the alcohol identity and content do affect the strength of 1) hydrophobic hydration of the SDA and 2) the water-alcohol interaction, through changing the efficiency of the interchanges between clathrated water molecules and solvated silicate species.

Study of Mechanisms of Nucleation and Growth in Zeolite Crystallization

Author : Juliusz Warzywoda
Publisher :
ISBN 13 :
Total Pages : 738 pages
Book Rating : 4.:/5 (213 download)

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Book Synopsis Study of Mechanisms of Nucleation and Growth in Zeolite Crystallization by : Juliusz Warzywoda

Download or read book Study of Mechanisms of Nucleation and Growth in Zeolite Crystallization written by Juliusz Warzywoda and published by . This book was released on 1989 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Zeolites and Catalysis

Author : Jiri Cejka
Publisher : John Wiley & Sons
ISBN 13 : 9783527630301
Total Pages : 918 pages
Book Rating : 4.6/5 (33 download)

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Book Synopsis Zeolites and Catalysis by : Jiri Cejka

Download or read book Zeolites and Catalysis written by Jiri Cejka and published by John Wiley & Sons. This book was released on 2010-05-27 with total page 918 pages. Available in PDF, EPUB and Kindle. Book excerpt: This indispensable two-volume handbook covers everything on this hot research field. The first part deals with the synthesis, modification, characterization and application of catalytic active zeolites, while the second focuses on such reaction types as cracking, hydrocracking, isomerization, reforming and other industrially important topics. Edited by a highly experienced and internationally renowned team with chapters written by the "Who's Who" of zeolite research.

Zeolite Beta Mechanisms of Nucleation and Growth

Author : Nathan D. Hould
Publisher :
ISBN 13 : 9781267214928
Total Pages : pages
Book Rating : 4.2/5 (149 download)

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Book Synopsis Zeolite Beta Mechanisms of Nucleation and Growth by : Nathan D. Hould

Download or read book Zeolite Beta Mechanisms of Nucleation and Growth written by Nathan D. Hould and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeolites are microporous aluminosilicates widely used in industrial processes as catalysts, supports, and adsorbents. To synthesize zeolite crystal particles with uniform morphology and controlled size the role of structure directing agents (organic and inorganic cations) in zeolite nucleation and growth needs to be understood. Zeolite beta is a model material to study how the interaction between isomorphous trivalent heteroatom substitutions (e.g., [AlO 2] - ) and structure directing agents (e.g., tetraethylammonium (TEA +) and Na +) effect zeolite nucleation and growth because it is can be synthesized having [SiO 2] to [AlO 2] - ratios from oo to 3. Zeolite beta has been prepared in dilute (H 2 O/SiO 2 = 80) and concentrated (H 2 O/SiO 2 = 20) synthesis solutions. The rates of zeolite beta nucleation and growth in dilute colloidal solutions have been characterized using dynamic light scattering and small angle X-ray scattering. By blending TEA + and Na + in dilute solutions at low Al concentration (Si/Al = 50) it has been determined that nucleation rate decreases and growth rate increases (colloidal stability decreases) because of competition between TEA + and Na + for surface adsorption sites and occlusion into the precursor particles. Using more concentrated synthesis solutions the role of ion pairs (e.g., [=-SiO - TEA +], [[AlO 2] - TEA +], and [[AlO 2] - Na +]) in the precursor particles and the zeolite beta product was investigated in detail. Thermal gravimetric analyses have helped determine relation between synthesis condition and the ion pairs formed in the zeolite beta product. On the basis of the energies associated with these ion pairs a state diagram of zeolite beta including surface structure and phase selectivity has been developed. The relative rate of zeolite beta nucleation to growth has also been investigated by changing the ratio of TEA + and Na + . The synergy between these cations and anionic surface adsorption sites has led to synthesis of nearly monodisperse zeolite beta crystal particles having sizes from about 100 to 500 nm.

Chemistry of Zeolites and Related Porous Materials

Author : Ruren Xu
Publisher : John Wiley & Sons
ISBN 13 : 0470822368
Total Pages : 616 pages
Book Rating : 4.4/5 (78 download)

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Book Synopsis Chemistry of Zeolites and Related Porous Materials by : Ruren Xu

Download or read book Chemistry of Zeolites and Related Porous Materials written by Ruren Xu and published by John Wiley & Sons. This book was released on 2009-05-29 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: Widely used in adsorption, catalysis and ion exchange, the family of molecular sieves such as zeolites has been greatly extended and many advances have recently been achieved in the field of molecular sieves synthesis and related porous materials. Chemistry of Zeolites and Related Porous Materials focuses on the synthetic and structural chemistry of the major types of molecular sieves. It offers a systematic introduction to and an in-depth discussion of microporous, mesoporous, and macroporous materials and also includes metal-organic frameworks. Provides focused coverage of the key aspects of molecular sieves Features two frontier subjects: molecular engineering and host-guest advanced materials Comprehensively covers both theory and application with particular emphasis on industrial uses This book is essential reading for researches in the chemical and materials industries and research institutions. The book is also indispensable for researches and engineers in R&D (for catalysis) divisions of companies in petroleum refining and the petrochemical and fine chemical industries.

Synthesis of Zeolite Nanocrystals and Their Application for Mixed Matrix Membranes

Author : Dan Li (Chemical engineer)
Publisher :
ISBN 13 :
Total Pages : 272 pages
Book Rating : 4.:/5 (92 download)

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Book Synopsis Synthesis of Zeolite Nanocrystals and Their Application for Mixed Matrix Membranes by : Dan Li (Chemical engineer)

Download or read book Synthesis of Zeolite Nanocrystals and Their Application for Mixed Matrix Membranes written by Dan Li (Chemical engineer) and published by . This book was released on 2009 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeolites are a class of microporous solids with well-defined crystalline structures. Due to their ability to distinguish molecules on the basis of size and shape, zeolites are often referred to as molecular sieves. There has been considerable interest in the synthesis of zeolite nanocrystals (or nanozeolites), because they can serve as a model system for fundamental understanding of zeolite nucleation and growth mechanisms, as seeds for secondary growth of zeolite films and membranes, as building blocks for construction of hierarchical porous nanostructures, and for preparation of mixed matrix membranes (MMMs). Presently, in the synthesis of zeolite crystals, it is well-known that the addition of organic additives or polymers has an effect on the zeolite nucleation and crystallization. Despite several synthetic strategies of using some polymers (e.g. polyacrylamide and methylcellulose) have been developed to grow zeolites, there has been no research on the synthesis with crosslinked chitosan hydrogels or uncrosslinked chitosan polymers, which is one primary goal of this thesis. Therefore, chitosan (crosslinked or uncrosslinked polymers) was introduced into zeolite crystallization process. The zeolite crystal sizes were significantly affected by formulation of silica-containing crosslinked hydrogels and alkaline solution, and by aging and heating conditions. Importantly, a novel method of using hydrogen peroxide solution was developed to remove crosslinked hydrogels after zeolite synthesis, which was considered as an effective way for removal of hydrogels. The resultant zeolite nanocrystals were readily redispersed in deionized water and some other solvents, and therefore they may be useful for some applications, e.g. in the fabrication of zeolite-polymer mixed matrix membranes (MMMs) and hierarchical porous zeolitic structures. In this thesis, the effect of uncrosslinked chitosan hydrogels on zeolite nucleation and crystallization was also studied. Cubic zeolite with a single crystalline shell and an amorphous core was prepared for the first time by in-situ crystallization of sodium aluminosilicate gel inside the chitosan polymer networks. The TEM characterization further revealed that this formation process of cube-like or rectangular core-shell structures involved particle aggregation and surface-to-core crystallization induced by chitosan networks. It is expected that this work would provide a new model system for understanding and studying complex zeolite nucleation and growth mechanisms. To date, the research into efficient separation of hydrogen has been driven by its potential as an essential component of future energy economies. Despite some materials emerging for this purpose, it is believed that there should be plenty of room to develop mixed matrix membranes (MMMs) with an addition of inorganic particles, such as zeolites, for hydrogen separation or purification. In order to reduce the phase separation between organic and inorganic phases, organic functionalization is suggested as an effective way, which has been applied in my study. Sodalite, whose framework consists of a six-membered ring aperture, was selected as inorganic fillers in MMMs. To functionalize sodalite nanocrystals, organic functional groups were successfully attached to sodalite nanocrystals by the newly developed method - the direct transformation of organic-functionalized silicalite nanocrystals. Organic-functionalized sodalite nanocrystals were incorporated into polyimide membranes to form sodalite MMMs for hydrogen separation. Characterization by SEM showed that zeolite can be well distributed with polyimide phase, as confirmed by the FTIR spectroscopy and XRD results. TG results revealed the temperatures for corresponding major mass loss increased with the increasing inorganic content of MMMs. This was attributed to the interaction between the amino moieties from inorganic nanoparticles and polymer matrix, which restricted the movement of the main chains. The gas permeation results exhibited the significantly improved hydrogen separation property.

Polyoxometalate Chemistry

Author : Francis Secheresse
Publisher : World Scientific
ISBN 13 : 9814458988
Total Pages : 360 pages
Book Rating : 4.8/5 (144 download)

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Book Synopsis Polyoxometalate Chemistry by : Francis Secheresse

Download or read book Polyoxometalate Chemistry written by Francis Secheresse and published by World Scientific. This book was released on 2013 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book highlights recent prominent results in the domain of the synthesis of new polyoxometalates with a specific attention to polyoxothioanions, and provides some novelties and perspectives in selected domains such as magnetism, luminescence and nanochemistry, and macroions self-assembly in solutions. The case of OC one-potOCO syntheses often used and reported in POMs synthesis is studied in terms of more complex solution speciation processes related to highly dynamical situation connected to factors such as pH, ionic strength, reaction time, temperature, counterion nature, concentration of starting materials, presence of electron donors and redox potentials. The behavior of macroions (2nm-6nm size range) in solution is shown to be quite different from the simple ionic solution or colloidal systems (DebyeOCoHuckel model). Their self-assembling into a single-layered, spherical, hollow vesicle structure, namely the OC blackberryOCO structure, is clearly described. Examples of spin clusters with tunable interactions are given and single molecule magnets based on POMs are specifically tackled. Besides paramagnetic transition metal centres and lanthanoid ions encapsulated in archetypal lacunary polyoxoanions, magnetically functionalized Kleperates are described, their discovery tracing back nearly 15 years.

Molecular Sieve Zeolites

Author : Edith M. Flanigen
Publisher :
ISBN 13 :
Total Pages : 546 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Molecular Sieve Zeolites by : Edith M. Flanigen

Download or read book Molecular Sieve Zeolites written by Edith M. Flanigen and published by . This book was released on 1971 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Zeolite Synthesis

Author : Mario L. Occelli
Publisher :
ISBN 13 :
Total Pages : 672 pages
Book Rating : 4.:/5 (44 download)

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Book Synopsis Zeolite Synthesis by : Mario L. Occelli

Download or read book Zeolite Synthesis written by Mario L. Occelli and published by . This book was released on 1989 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is a complete progress report on the various aspects of zeolite synthesis on a molecular level. It provides many examples that illustrate how zeolites can be crystallized and what the important parameters are that control crystallization. Forty-two chapters cover such topics as: crystallization techniques; gel chemistry; crystal size and morphology; the role of organic compounds; and novel synthesis procedures. It offers a complete review of zeolite synthesis as well as the latest finding in this important field. Contains benchmark contributions from many notable pioneers in the field, including R.M. Barrer, H. Robson, and Robert Milton.

Chemistry of Silica and Zeolite-Based Materials

Author : Abderrazzak Douhal
Publisher : Elsevier
ISBN 13 : 0128178140
Total Pages : 464 pages
Book Rating : 4.1/5 (281 download)

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Book Synopsis Chemistry of Silica and Zeolite-Based Materials by : Abderrazzak Douhal

Download or read book Chemistry of Silica and Zeolite-Based Materials written by Abderrazzak Douhal and published by Elsevier. This book was released on 2019-07-04 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemistry of Silica and Zeolite-Based Materials covers a wide range of topics related to silica-based materials from design and synthesis to applications in different fields of science and technology. Since silica is transparent and inert to the light, it is a very attractive host material for constructing artificial photosynthesis systems. As an earth-abundant oxide, silica is an ideal and basic material for application of various oxides, and the science and technology of silica-based materials are fundamentally important for understanding other oxide-based materials. The book examines nanosolvation and confined molecules in silica hosts, catalysis and photocatalysis, photonics, photosensors, photovoltaics, energy, environmental sciences, drug delivery, and health. Written by a highly experienced and internationally renowned team from around the world, Chemistry of Silica and Zeolite-Based Materials is ideal for chemists, materials scientists, chemical engineers, physicists, biologists, biomedical sciences, environmental scientists, toxicologists, and pharma scientists. --- "The enormous versatility of silica for building a large variety of materials with unique properties has been very well illustrated in this book.... The reader will be exposed to numerous potential applications of these materials – from photocatalytic, optical and electronic applications, to chemical reactivity in confined spaces and biological applications. This book is of clear interest not only to PhD students and postdocs, but also to researchers in this field seeking an understanding of the possible applications of meso and microporous silica-derived materials." - Professor Avelino Corma, Institute of Chemical Technology (ITQ-CSIC) and Polytechnical University of Valencia, Spain Discusses the most important advances in various fields using silica materials, including nanosolvation and confined molecules in silica hosts, catalysis and photocatalysis, and other topics Written by a global team of experts from a variety of science and technology disciplines Ideal resource for chemists, materials scientists, and chemical engineers working with oxide-based materials

Synthesis of High-Silica Aluminosilicate Zeolites

Author : J.A. Martens
Publisher : Elsevier
ISBN 13 : 0080960677
Total Pages : 407 pages
Book Rating : 4.0/5 (89 download)

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Book Synopsis Synthesis of High-Silica Aluminosilicate Zeolites by : J.A. Martens

Download or read book Synthesis of High-Silica Aluminosilicate Zeolites written by J.A. Martens and published by Elsevier. This book was released on 1987-05-01 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of all new high-silica zeolites which have been discovered between 1975 and 1985. The first part presents some 25 proven recipes for the preparation of high-silica zeolites and describes the characteristics of the materials obtained. This will allow bench-scale production of these materials for scientific research. In the second part, high-silica zeolites with solved structure type are discussed. This part classifies many proprietary materials according to known structure types, and describes the rules and parameters which govern the formation of these materials. In the third part, the formation and characteristics of high-silica zeolites with unknown structure type are discussed. The book contains a wealth of information for all those scientists who incorporate the use of high-silica zeolites in their work.

Verified Synthesis of Zeolitic Materials

Author : H. Robson
Publisher : Gulf Professional Publishing
ISBN 13 : 9780444507037
Total Pages : 288 pages
Book Rating : 4.5/5 (7 download)

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Book Synopsis Verified Synthesis of Zeolitic Materials by : H. Robson

Download or read book Verified Synthesis of Zeolitic Materials written by H. Robson and published by Gulf Professional Publishing. This book was released on 2001-06-26 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zeolite synthesis is an active field of research. As long as this continues, new phases will be discovered and new techniques for preparing existing phases will appear. This edition of Verified Synthesis of Zeolitic Materials contains all the recipes from the first edition plus 24 new recipes. Five new introductory articles have been included plus those from the first edition, some of which have been substantially revised. The XRD patterns have been recorded using different instrument settings from those in the first edition and are intended to conform to typical X-ray diffraction practice. In most cases, only the XRD pattern for the productas synthesised is printed here. The exceptions are those phases which show marked changes in the XRD pattern upon calcination.

Zeolites

Author : B. Držaj
Publisher : Elsevier
ISBN 13 : 0080960588
Total Pages : 707 pages
Book Rating : 4.0/5 (89 download)

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Book Synopsis Zeolites by : B. Držaj

Download or read book Zeolites written by B. Držaj and published by Elsevier. This book was released on 2011-09-22 with total page 707 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis of zeolites with desired structure and properties is of great importance for the preparation of highly active and selective catalysts for inorganic and organic reactions. The zeolite matrix offers unique possibilities for carrying out molecular shape-selective catalysis and this places the zeolite matrices among the most successful tools used in molecular engineering on a large scale.These proceedings cover the most recent developments in the fields of synthesis, structure determination and technological use of zeolites. The papers give detailed explanations of the processes involved in the mechanisms of zeolite synthesis. Special attention is focussed on complex ionic equilibria which occur in the starting hydrogel, to the ``templating effect'' and to the kinetics of zeolite formation. New powerful methods for structure determination of these materials, which usually consist of small crystals, are presented e.g. neutron diffraction and X-ray diffraction using synchrotron radiation. The distribution of tetrahedrally coordinated framework-constituent elements and their interaction with adsorbates is revealed by using high magnetic field nuclear magnetic resonance with sample spinning at ``magic'' angle (MAS NMR).Quite a number of articles are devoted to the dependence of the physico-chemical properties of zeolites on the parameters set during their synthesis. Descriptions are given of the possible technological use of synthetic zeolites in the fields of adsorption, catalysis, the production of laundry detergents, the removal of radioactive wastes, and the technological use of natural zeolites in the fields of animal feeding, municipal water treatment, paper and cement production, and energy storage. This book will be of interest to scientists working in the fields of catalysis, surface science, inorganic chemistry, materials science, petrochemistry, solid state physics, crystallography and geology.

Zeolite Nanocrystals and Hierarchical Porous Structures: Synthesis, Characterization and Formation Mechanism

Author : Yi Huang
Publisher :
ISBN 13 :
Total Pages : 140 pages
Book Rating : 4.:/5 (11 download)

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Book Synopsis Zeolite Nanocrystals and Hierarchical Porous Structures: Synthesis, Characterization and Formation Mechanism by : Yi Huang

Download or read book Zeolite Nanocrystals and Hierarchical Porous Structures: Synthesis, Characterization and Formation Mechanism written by Yi Huang and published by . This book was released on 2011 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant effort has been made to synthesize zeolite nanocrystals with controllable crystal sizes and high yield. A number of synthetic strategies involving optimization of hydrothermal conditions and/or composition of synthesis solutions (or gels), and phase transformation have been developed so far. However, controlled synthesis of zeolite nanocrystals still remains one of the difficult tasks in many systems due to their very complex crystallization mechanisms. Especially, in a zeolite synthesis system (clear solution or gel) without using a structure-directing agent (SDA), only a limited success has been achieved in controlling crystal sizes. In this dissertation, a novel synthesis method combining space confined synthesis and templating approach has been developed to prepare zeolite nanocrystals with controlled particle size distributions. This synthetic strategy involves the following steps: selection of colloidal silica nanoparticles; formation of silica-mesoporous carbon composite by in situ polymerization of furfuryl alcohol (FA) in the presence of triblock copolymer-Pluronic P123 and colloidal silica nanoparticles and subsequent carbonization; confined space conversion of silica nanoparticles into zeolite nanocrystals; and sample collection via carbon burn-off. This novel synthesis method allows one to control nanocrystal size and size distribution simply by choosing colloidal silica nanoparticles with a desired particle size distribution.Zeolites with hierarchical porous structures and designed shapes are in high demand for new technological as well as traditional applications (for instance as catalysts or highly selective adsorbents). In this study, hierarchical porous particles (150-600 nm) aggregated by primary NaY zeolite nanocrystals (20-80 nm) have been synthesized without using a secondary template via a newly developed three-stage temperature controlled strategy. The mesoporosity of synthesized particles, possessing a globular crystal-like morphology, can be tuned in the range of 30.8-57.6% by simply varying water contents in the synthesis gels. The mechanistic study of zeolite NaY growth in this organic-free system suggested that the formation mechanism that governed the crystallization process was similar to that reported by Valtchev and Bozhilov, i.e., fast spontaneous aggregation of nanoparticles around a crystallization center, followed by crystallization and agglomeration of larger crystals around these centers. This approach to the preparation of hierarchical porous zeolite particles can be applied to a number of zeolite materials.Core-shell/hollow zeolite NaP particles and macroporous NaP monoliths with designed shapes (such as cylinder, rectangular-prism and donut shapes) have been fabricated by combing the ceramic gel-casting technique and in situ vapour phase transport (VPT) method. It has been found that the employment of aged zeolite gel as the starting material is a prerequisite for the successful formation of NaP zeolite structures. However, by incorporating different amounts of silica nanoparticles in the gel-casting process, one can control the mechanical strength and Si/Al ratio of the resulting zeolitic monoliths. Dispersible and individual hollow NaP zeolite particles with relatively lower Si/Al ratios have been produced in the absence of colloidal silica. Careful analyses of the samples collected after a series of crystallization times revealed that the growth of the core-shell/hollow NaP structures possibly followed a surface-to-core formation process. The fabrication of macroporous zeolite monoliths with functional magnetic Fe3O4 has been presented, demonstrating the feasibility of this synthetic approach for zeolite functionalization.It is well known that the addition of organic additives has an effect on zeolite nucleation and crystallization. The role of ethanol in sodalite crystallization was systematically studied in 3.09Na2O: 1.00Al2O3: 1.08SiO2: 45.5H2O: nC2H6O (nethanol = 0, 3.6, 7.2, 14.5, 29 and 43.5) systems. It has been found that the introduction of ethanol into the gel system significantly facilitated phase transformation from LTA to a denser SOD phase. Moreover, the increase in the amount of ethanol in gel systems has led to the morphological evolution of as-synthesized sodalites from clusters of micro-sized discs to nanoplates assembled thread-ball-like particles, and then to globular polyhedral nanocrystals aggregated core-shell/hollow structures. Importantly, in the system with high ethanol contents (nethanol ≥ 14.5), where core-shell/hollow sodalites were formed, extraordinary phenomena including multiple surface nucleation and crystallization followed by surface-to-core growth, have been observed. Supported by experimental evidence obtained in this work, surface nucleation and crystallization is probably a common process, in particular when an appropriate amount of alcohol is involved in zeolite synthesis.

Environmentally Friendly Zeolites

Author : Rafael Chaves Lima
Publisher : Springer
ISBN 13 : 3030199703
Total Pages : 111 pages
Book Rating : 4.0/5 (31 download)

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Book Synopsis Environmentally Friendly Zeolites by : Rafael Chaves Lima

Download or read book Environmentally Friendly Zeolites written by Rafael Chaves Lima and published by Springer. This book was released on 2019-05-24 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book details zeolites, their structures and the parameters that influence their synthesis, providing a new and actual perspective of this field. Following this, the authors show different processes used to synthesize zeolites using residues, natural materials, and other eco-friendly materials such as raw powder glass, clays, aluminum cans, diatomites, rice ashes or coal ashes. Finally, this book gives the reader a wide range of different synthesis methods that they can be applied to several industrial processes.

Zeolite Microporous Solids: Synthesis, Structure, and Reactivity

Author : E.G. Derouane
Publisher : Springer Science & Business Media
ISBN 13 : 9401126046
Total Pages : 635 pages
Book Rating : 4.4/5 (11 download)

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Book Synopsis Zeolite Microporous Solids: Synthesis, Structure, and Reactivity by : E.G. Derouane

Download or read book Zeolite Microporous Solids: Synthesis, Structure, and Reactivity written by E.G. Derouane and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intensive research on zeolites, during the past thirty years, has resulted in a deep understanding of their chemistry and in a true zeolite science, including synthesis, structure, chemical and physical properties, and catalysis. These studies are the basis for the development and growth of several industrial processes applying zeolites for selective sorption, separation, and catalysis. In 1983, a NATO Advanced Study Institute was organized in Alcabideche (portugal) to establish the State-of-the-Art in Zeolite Science and Technology and to contribute to a better understanding of the structural properties of zeolites, the configurational constraints they may exert, and their effects in adsorption, diffusion, and catalysis. Since then, zeolite science has witnessed an almost exponential growth in published papers and patents, dealing with both fundamentals issues and original applications. The proposal of new procedures for zeolite synthesis, the development of novel and sophisticated physical techniques for zeolite characterization, the discovery of new zeolitic and related microporous materials, progresses in quantum chemistry and molecular modeling of zeolites, and the application of zeolites as catalysts for organic reactions have prompted increasing interest among the scientific community. An important and harmonious interaction between various domains of Physics, Chemistry, and Engineering resulted therefrom.