2 edition of Cation self-diffusion in zeolites. found in the catalog.
Cation self-diffusion in zeolites.
A. B. Ogden
MSc thesis, Chemistry.
The influence of the compensating cation (Na+, Li+, Mg2+) nature on the water adsorption properties of LTA and FAU-type zeolites was investigated. Cation exchanges were performed at 80 °C for 2 h using 1 M aqueous solutions of lithium chloride (LiCl) or magnesium chloride (MgCl2). XRF and ICP-OES analyses indicate that the cation exchange yields reach values between 59 to 89% depending on the. cracking catalyst. In Grace described the ﬁ rst modiﬁ cation chemistry based on steaming zeolite Y to form an “ ultrastable ” Y. In – Mobil Oil reported the synthesis of the high silica zeolites beta and ZSM - 5. In Henkel introduced zeolite A in detergents as a replacement for the environmentally suspect phos-phates.
The idealized, stoichiometric formula, given to zeolites is: M x/n [Al x Si y O 2(x + y)]pH 2 O, where M - (Na, K, Li); (Ca, Mg, Ba, Sr); n - charge of a cation; y/x = ; p/x = The oxide formula of zeolites is: M 2/n O Al 2 O 3 xSiO 2 yH 2 O.. The pore size refers to a two-dimensional “window” within the zeolite structure and is determined by the number of tetrahedral units. H. Jobic's research works with 3, citations and 4, reads, including: Exploration of the Long-Chain N-Alkanes Adsorption and Diffusion in the MOF-Type MIL (V) Material by Combining.
Cation exchange isotherms have been constructed for three high silica zeolites: *BEA (beta), EUO (EU-1) and TON (NU).The zeolites were converted to their homoionic sodium forms and exchanges with Li, K, Rb, Cs, Mg, Sr, Ba, Ni and Zn carried out. From the isotherms thermodynamic parameters were calculated and used to suggest ion exchange mechanisms. Comparisons to similar processes in other. Rh ion-exchanged MFI-type aluminosilicate zeolites with different Al distributions were prepared for controlling the location, state, and size of Rh MFI-type aluminosilicate zeolite with the framework Al atoms predominantly located inside the channel intersections leads to the formation of relatively large Rh species, which were confirmed by ultraviolet-visible (UV-vis) and.
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Self-diffusion parameters have been measured for Ca 2+, Sr 2+ and Ba 2+ cations in the synthetic zeolite ZK4. The anomalous nature of Ba 2+ migration is discussed and comparisons are made to ionic movements in A and X zeolites and in chabazite.
Cited by: 7. Journals & Books; Register Sign in. Sign in Register. Journals & Books; Help; COVID campus closures: see options for getting or retaining Remote Access to subscribed content Cited by: 7.
Self-diffusion measurements A weighed quantity of hydrated homoionic zeolite was rotated for 24 hr at a temperature of Cation self-diffusion in zeolites.
book in contact with a known volume of solution. This solution contained a suitable amount of a radio- isotope of the cation whose diffusion was to be studied. The activity of this solution was known (C1).Cited by: When cation movements are followed in the absence of an external chemical potential, progress through the zeolite structure is generally slower, which could be anticipated.
The energy barrier to sodium self-diffusion estimated by Ames  is much lower than any quoted here and cannot be explained except to point out that it was estimated from measurements at only two by: Beyond Lattice Models of Activated Transport in Zeolites: High-Temperature Molecular Dynamics of Self-Diffusion and Cooperative Diffusion of Benzene in NaX.
The Journal of Physical Chemistry B(44), DOI: /jp Pradip by: INTRODUCTION THE INVESTIGATION of the properties of zeolites and of cations in the zeolite framework by measurement of self-diffusion kinetics is a well-established tech- nique and has been extensively used in the past.
Authored by an international team of renowned scientists, the seven chapters of this book present a comprehensive overview of the application of zeolites in industrial catalysis, while also providing a true scientific understanding of how zeolites are synthesized, modified and characterized, and providing special emphasis on shape-selective catalysis, which is a unique feature of zeolites.
Contents VII Multi-Technique Methodology 86 Identiﬁ cation of the Structure of a Newly Invented Zeolite 86 X-Ray Powder Diffraction Characterization of Zeolitic Systems 91 Interpretation of Powder Diffraction Data for Zeolites 91 Phase Identiﬁ cation and Quantiﬁ cation 92 Unit Cell Size Determination 94 Crystallite Size About this book.
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.
published more than peer-reviewed scientiﬁc articles and ﬁve books. He is the organic cation into the zeolite can be controlled precisely and.
the self-diffusion of methanol in the. Zeolite A, also known as LTA (Linde Type A), belongs to the family of aluminosilicate molecular sieves. It is characterized by the formula |(Na + 12 (H 2 O) 27 | 8 [Al 12 Si 12 O 48] 8 which corresponds to its most common hydrated sodium form (International Zeolite Association -IZA).
Sodium ions in zeolite A can be exchanged with other cations such as lithium (Li-LTA), potassium (K-LTA), or. We have studied a lattice model of self-diffusion in nanopores, to explore how loading, temperature, and adsorbate coupling influence benzene self-diffusion in Na–X and Na–Y zeolites.
The cation exchange capacity of the zeolite is distinctly dependent on its original cationic composition, because not all the cationic sites in the zeolite structure are available for cation exchange. Removal efficiency of ions from water solution increases with higher portion of the main component of natural zeolite.
Intensive studies of natural and synthetic zeolites properties are being held from the middle of ies. Among the various examples of zeolites application it is sufficient to mention emission and purification of normal paraffin hydrocarbons, catalytic reactions of hydrocarbons, extraction of radioactive isotopes, obtaining carriers for catalysts, release of enzymes and removal of.
Back to book. chapter Chapter 2. 23 Pages. Modern Theories of Ion Exchange and Ion Exchange Selectivity with Particular Reference to Zeolites. The fully La-exchanged form of the large pore zeolite L, La Al Si O 72, has been prepared by repeated aqueous ion exchange and internal cation exchange resulting from calcination to give a low silica zeolite (Si/Al = 3) with all cations hidden from available results from the migration of La 3+ from sites in the large membered ring (12R) channel (exchangeable via.
Natural zeolites have a high cation exchange capacity and selectivity due to their high porosity and sieving properties (Zhao et al. Clinoptilolite and mordenite zeolite materials have a theoretical cation exchange capacity (CEC) of mEq/ g (Pabalan and Bertetti ) (Fig. The self-diffusion of cations in synthetic zeolite ZK4.
Journal of Inorganic and Nuclear Chemistry,32 (1), (70) A. Dyer, R.B. Gettins, A. Molyneux. Stability and cation self-diffusion in barium Type A zeolite. Self-diffusion parameters of zinc into zeolites X and Y, of Si:Al atios of 126, 187 and 262 respectively, have been determined at low and high temperatures.
Cation sieving may be due to the inability of the negative charge distribution on the zeolite structure to accommodate a given cation. Table 1. Representative formulae, chemical composition, and selected physical properties of important zeolites [ 25, 26 ]. This article is cited by 11 publications.
HOWARD S. SHERRY. Cation Exchange on Zeolites.Zeolite softening does not reduce alkalinity, and demineralization is too costly. For these situations, a dealkalization process is used.
Sodium zeolite/hydrogen zeolite (split stream) dealkalization, chloride-anion dealkalization, and weak acid cation dealkalization are the most frequently used processes.The H2O self-diffusion in hydrated fibrous zeolites (natrolite, mesolite, and scolecite) at hydrostatic pressure up to GPa was investigated using nuclear magnetic resonance.