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Sieving, molecular

Molecular sieving is the dominating transport mechanism when the pore size is comparable to the molecular dimensions, 3-5 A hence the smallest molecule will permeate, and the larger will be retained. The dimensions of a molecule are usually described with either the Lennard-Jones radii or the Van der Waal radii. Eor separation by molecular sieving, this is not a satisfactory way of stating the molecular size a shape factor should also be included [9]. [Pg.72]

The sorption selectivity has little influence on the separation when molecular sieving is considered. An Arrhenius type of equation is still valid for the activated transport, but attention should be drawn to the pre-exponential term, Dq (see Equation 4.7). From transition state theory this factor may be expressed as shown in Equation 4.15 [32]  [Pg.72]

A change in entropy will thus have a significant effect on the selectivity when molecular sieving is considered. This is thoroughly discussed by Singh and Koros [9]. The flux may be described as in Equation 4.16 where Eq.ms is the activation energy for diffusion in the molecular sieving media. [Pg.73]

The selectivity for separation will normally decrease with increasing temperature because of increased diffusion rate for permeating components, and the sorption will be of minor importance. [Pg.73]


Gel permeation chromatography, exclusion chromatography. gel filtration chromatography. A technique for separating the components of a mixture according to molecular volume differences. A porous solid phase (a polymer, molecular sieve) is used which can physically entrap small molecules in the pores whilst large molecules pass down the column more rapidly. A solvent pressure up to 1000 psi may be used. [Pg.98]

For physical processes, two examples are the elimination of normal paraffins from a mixture by their adsorption on 5 A molecular sieves or by their selective formation of solids with urea (clathrates)... [Pg.26]

This type of analysis requires several chromatographic columns and detectors. Hydrocarbons are measured with the aid of a flame ionization detector FID, while the other gases are analyzed using a katharometer. A large number of combinations of columns is possible considering the commutations between columns and, potentially, backflushing of the carrier gas. As an example, the hydrocarbons can be separated by a column packed with silicone or alumina while O2, N2 and CO will require a molecular sieve column. H2S is a special case because this gas is fixed irreversibly on a number of chromatographic supports. Its separation can be achieved on certain kinds of supports such as Porapak which are styrene-divinylbenzene copolymers. This type of phase is also used to analyze CO2 and water. [Pg.71]

Feedstocks are natural gas, refinery fuel gas, LPG and paraffinic naphthas. After elimination of CO2, the last traces of contaminants are converted to methane (methanation) or eliminated by adsorption on molecular sieves (PSA process). [Pg.391]

Gases which are high in FIjS are subject to a de-sulphurisation process in which H2S is converted into elemental sulphur or a metal sulphide. There are a number of processes based on absorption in contactors, adsorption (to a surface) in molecular sieves or chemical reaction (e.g. with zinc oxide). [Pg.254]

Electron Spin Resonance Spectroscopy. Several ESR studies have been reported for adsorption systems [85-90]. ESR signals are strong enough to allow the detection of quite small amounts of unpaired electrons, and the shape of the signal can, in the case of adsorbed transition metal ions, give an indication of the geometry of the adsorption site. Ref. 91 provides a contemporary example of the use of ESR and of electron spin echo modulation (ESEM) to locate the environment of Cu(II) relative to in a microporous aluminophosphate molecular sieve. [Pg.586]

D. W. Breck, Zeolite Molecular Sieves, Wiley-Interscience, New York, 1974. [Pg.676]

W. H. Flank and T. Whyte, Perspective in Molecular Sieve Science, ACS Symposium Series, No. 135, American Chemical Society, Washington, DC, 1980. [Pg.676]

Zeolites (section C2.13) are unique because they have regular pores as part of their crystalline stmctures. The pores are so small (about 1 nm in diameter) that zeolites are molecular sieves, allowing small molecules to enter the pores, whereas larger ones are sieved out. The stmctures are built up of linked SiO and AlO tetrahedra that share O ions. The faujasites (zeolite X and zeolite Y) and ZSM-5 are important industrial catalysts. The stmcture of faujasite is represented in figure C2.7.11 and that of ZSM-5 in figure C2.7.12. The points of intersection of the lines represent Si or A1 ions oxygen is present at the centre of each line. This depiction emphasizes the zeolite framework stmcture and shows the presence of the intracrystalline pore stmcture. In the centre of the faujasite stmcture is an open space (supercage) with a diameter of about 1.2 nm. The pore stmcture is three dimensional. [Pg.2710]

Sumelius I G 1992 Attempted translation of the original old-Swedish paper by Cronstedt Molecular Sieves ed M L Ocelli and H E Robson (New York Van Nostrand Reinhold) pp 1-5... [Pg.2791]

Casci J L 1994 The preparation and potential applications of ultra-large pore molecular sieves a review Stud. Surf. Sc/. Catai. 85 329-56... [Pg.2791]

Kresge C T, Leonowicz M E, Roth W J, Vartuli J C and Beck J S 1992 Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism Nature 359 710-12... [Pg.2791]

Flanigen E M, Bennet J M, Grose R W, Cohen J P, Patton R L, Kirchner R M and Smith J V 1978 Silicalite a new hydrophobic crystalline silica molecular sieve Nature 271 512-16... [Pg.2791]

Perego G, Millini R and Bellussi G 1998 Synthesis and characterization of molecular sieves containing transition metals in the framework Moiecuiar Sieves Science and Technoiogy vol 1, ed FI G Karge and J Weitkamp (Berlin ... [Pg.2791]

Schunk S A and Schuth F 1998 Synthesis of zeolite-like inorganic compounds Molecular Sieves Science and Technology vo 1, ed H G Karge and J Weitkamp (Berlin Springer) pp 229-63... [Pg.2792]

Martens J A and Jacobs P A 1999 Phosphate-based zeolites and molecular sieves Catalysis and Zeolites, Fundamentals and Applications ed J Weitkamp and L Puppe (Berlin Springer) pp 53-80... [Pg.2792]

McDaniel C V and Maher P K 1968 New ultra-stable form of fau]asite Molecular Sieves (London Society of Chemical Industry) pp 186-95... [Pg.2792]

Nadimi S, Oliver S, Kuperman A, Lough A, Ozin G A, Garces J M, Olken M M and Rudolf P 1994 Nonaqueous synthesis of large zeolite and molecular sieve crystals Stud. Surf. Sol. Catal. 84 93-100... [Pg.2792]

This book concentrates on synthesis and identification methods for molecular sieves including nonaluminosilicate molecular sieves and gives a good overview of structures and patented materials. [Pg.2793]

Catalytic system addition of molecular sieves to "soak" up any water with 3A sieves, 5-10 mol % catalyst is used,... [Pg.26]

The reaction of a halide with 2-butene-1,4-diol (104) affords the aldehyde 105, which is converted into the 4-substituted 2-hydroxytetrahydrofuran 106, and oxidized to the 3-aryl-7-butyrolactone 107[94], Asymmetric arylation of the cyclic acetal 108 with phenyl triflate[95] using Pd-BINAP afforded 109, which was converted into the 3-phenyllactone 110 in 72% ee[96]. Addition of a molecular sieve (MS3A) shows a favorable effect on this arylation. The reaction of the 3-siloxycyclopentene 111 with an alkenyl iodide affords the. silyl... [Pg.143]

The carbonylation of some alkyl halides such as iodocyclohexane (911) can be carried out under neutral conditions in the presence of N,N,N.N-tetre,-methylurea (TMU), which is a neutral compound, but catches generated hydrogen halide. Molecular sieves (MS-4A) are used for the same pur-pose[768]. Very reactive ethyl 3-iodobutyrate (912) is carbonylated to give ethyl methylsuccinate (913) in the presence of TMU. The expected elimination of HI to form crotonate, followed by carbonylation, does not occur. [Pg.262]

Molecular sieves 4X Molecules with effective diameter >4A 0.001 0.18 250... [Pg.1082]

R. M. Barrer, Zeolites and Clay Minerals as Sorbents and Molecular Sieves , p. 174, Academic Press, London and New York (1978). [Pg.39]

Fig. 4.20 DR plots for carbon dioxide adsorbed at 293 K on Linde molecular sieves. O, powder SA , powder 4A. (Reduced from the original diagram of Lamond and Marsh. )... Fig. 4.20 DR plots for carbon dioxide adsorbed at 293 K on Linde molecular sieves. O, powder SA , powder 4A. (Reduced from the original diagram of Lamond and Marsh. )...
The lower pressure sub-region is characterized by a considerable enhancement of the interaction potential (Chapter 1) and therefore of the enthalpy of adsorption consequently the pore becomes completely full at very low relative pressure (sometimes 0 01 or less), so that the isotherm rises steeply from the origin. This behaviour is observed with molecular sieve zeolites, the enhancement of the adsorption energy and the steepness of the isotherm being dependent on the nature of the adsorbent-adsorbate interaction and the polarizability of the adsorbate. -... [Pg.242]

A vast amount of research has been undertaken on adsorption phenomena and the nature of solid surfaces over the fifteen years since the first edition was published, but for the most part this work has resulted in the refinement of existing theoretical principles and experimental procedures rather than in the formulation of entirely new concepts. In spite of the acknowledged weakness of its theoretical foundations, the Brunauer-Emmett-Teller (BET) method still remains the most widely used procedure for the determination of surface area similarly, methods based on the Kelvin equation are still generally applied for the computation of mesopore size distribution from gas adsorption data. However, the more recent studies, especially those carried out on well defined surfaces, have led to a clearer understanding of the scope and limitations of these methods furthermore, the growing awareness of the importance of molecular sieve carbons and zeolites has generated considerable interest in the properties of microporous solids and the mechanism of micropore filling. [Pg.290]


See other pages where Sieving, molecular is mentioned: [Pg.264]    [Pg.432]    [Pg.76]    [Pg.199]    [Pg.255]    [Pg.662]    [Pg.662]    [Pg.2777]    [Pg.2779]    [Pg.2782]    [Pg.2788]    [Pg.2789]    [Pg.188]    [Pg.26]    [Pg.191]    [Pg.197]    [Pg.201]    [Pg.240]    [Pg.196]    [Pg.18]   
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18-membered ring structures, large pore zeolite molecular sieves

4 A Molecular sieves: Zeolites

4-A molecular sieves

5 A molecular sieve trap

Acid molecular sieves, reactions

Acrylic acid molecular sieves

Activity of Alkaline Earth-Modified Mesoporous Molecular Sieves

Adsorbent molecular sieve

Adsorbents molecular sieve carbons

Adsorbents molecular sieve zeolites

Adsorption by Carbon Molecular Sieves

Adsorption molecular sieve

Adsorption molecular sieve zeolites

Adsorption properties, aluminophosphate molecular sieves

Alcohols, secondary, oxidation molecular sieves

Allyl alcohols molecular sieves

Allylic oxidation molecular sieves

Aluminophosphate molecular sieves

Aluminophosphate-based molecular sieves

Aluminosilicate Zeolites and Silica Molecular Sieves

Aluminosilicate and Aluminophosphate Molecular-Sieve Catalysts

Aluminum phosphate molecular sieve

Anhydrous ethanol molecular sieves

Application of Molecular Sieves

Applications molecular sieves

Asymmetric epoxidation molecular sieves

Benzene into molecular sieves

Borosilicate molecular sieves

Calixarenes, Cyclodextrins, Molecular Sieves and Boxes

Capillary sieving electrophoresis protein molecular weight determination

Carbon activation molecular sieve

Carbon fiber composite molecular sieve

Carbon molecular sieve Knudsen diffusion

Carbon molecular sieve Subject

Carbon molecular sieve air separation

Carbon molecular sieve carbonization

Carbon molecular sieve characterization

Carbon molecular sieve high-temperature

Carbon molecular sieve hydrogen separation

Carbon molecular sieve industrial applications

Carbon molecular sieve material functionalization

Carbon molecular sieve material selection

Carbon molecular sieve membranes for gas separation

Carbon molecular sieve membranes permeance

Carbon molecular sieve membranes permeation

Carbon molecular sieve membranes polymeric membrane

Carbon molecular sieve membranes pores size

Carbon molecular sieve membranes selectivity

Carbon molecular sieve membranes separation factor with

Carbon molecular sieve membranes separation performance

Carbon molecular sieve microscopy

Carbon molecular sieve post-treatment

Carbon molecular sieve precursor preparation

Carbon molecular sieve pretreatment

Carbon molecular sieve production

Carbon molecular sieve selective surface flow

Carbon molecular sieve spectroscopy

Carbon molecular sieve transport mechanisms

Carbon molecular sieves

Carbon molecular sieves adsorption

Carbon molecular sieves catalysis

Carbon molecular sieves catalyst preparation

Carbon molecular sieves for air separation

Carbon molecular sieves isotherms

Carbon molecular sieves kinetic separation

Carbon molecular sieves manufacture

Carbon molecular sieves materials

Carbon molecular sieves reactor

Carbon molecular sieves results

Carbon molecular sieving membranes

Carbon molecular sieving membranes production process

Catalysis by zeolites and molecular sieves

Catalyst characterization, SAPO molecular sieves

Catalyst materials molecular sieves

Catalyst preparation, SAPO molecular sieves

Catalyst silicalite-1 molecular sieves synthesis

Catalysts titanosilicate molecular sieves

Changing the molecular sieve

Characterization of Carbon Molecular Sieve Carbons

Chromium-containing molecular sieves

Cloverite zeolites large pore zeolite molecular sieves

Clusters molecular sieve zeolites

Columns molecular sieve

Commercial applications carbon molecular sieve

Commercialization, molecular sieve

Commercialization, molecular sieve zeolites

Crystalline molecular sieves

Dehydration by molecular sieves

Desiccants molecular sieves

Dewatering, Filtration and Washing of Molecular Sieve Products

Diels-Alder reactions molecular sieves

Diffusion carbon molecular sieves

Diffusion in Zeolites and Carbon Molecular Sieves

Diffusion molecular sieve pellets

Effect on metal aluminophosphate molecular sieve synthesis

Electrophoretic molecular sieving

Enamine Synthesis over Molecular Sieves, D-Optimal Design

Encaged molecular sieves zeolite

Enzymes molecular sieves

Epoxidation on Titanium Silicate Molecular Sieves

Ethylene purification with molecular sieve

Examples of Molecular Sieving

Exchange resins molecular sieve

Ferrisilicate molecular sieves

Fractionation methods molecular-sieve

Framework oxide molecular sieves

Framework-substituted Molecular Sieves

From Zeolites to Aluminophosphate Molecular Sieves and Other Microporous Phosphates

History of Molecular Sieve Materials

Hollow fiber carbon molecular sieve

Hollow fiber carbon molecular sieve membranes

Hydrated aluminophosphate molecular sieves

Hydrogen Storage in Mesoporous Molecular Sieves and Pillared Clays

Hydrogen chloride molecular sieve

Hydrogen molecular sieve

Inorganic oxide-modified carbon molecular sieve

Iron, removal from molecular sieve

Iron-containing molecular sieves, synthesi

Isomorphously Substituted Molecular Sieves

Large pore molecular sieves

Large pore molecular sieves incorporation

Large pore zeohte molecular sieves

Large pore zeolite molecular sieves phosphate structures

Large pore zeolites, molecular sieves phosphates

Large pore zeolites, molecular sieves silicates

Lewis acid sites molecular sieves

M41S materials, mesoporous molecular sieves

M41S materials, mesoporous molecular sieves silicates

MOLECULAR SIEVE INCIDENTS

MeAPO-5 molecular sieves

Membrane modules carbon molecular sieve

Mesoporous Molecular Sieve Adsorbents

Mesoporous molecular sieves

Mesoporous molecular sieves properties

Mesoporous molecular sieves, example

Mesoporous molecular sieves, formation

Mesoporous molecular sieves, structural

Mesoporous molecular sieves, structural properties

Mesoporous molecular sieves, structural silicates

Mesoporous silica molecular sieve

Metal aluminophosphate molecular sieves

Metal organic frameworks molecular sieves

Metal redox molecular sieves

Metal salts Molecular sieves

Metal-Substituted Mesoporous Silica Molecular Sieves

Metal-substituted Molecular Sieves as Catalysts for Allylic and Benzylic Oxidations

Microporous carbon materials molecular sieves

Microporous carbon molecular sieves

Microporous metal oxides - octahedral molecular sieves

Microporous molecular sieves

Microporous molecular sieves, formation

Mixture Molecular sieves

Moisture Molecular sieves

Moisture scavengers Molecular sieves

Molecular Sieve Membranes for Gas Separation

Molecular Sieving Membranes

Molecular diffusion sieves

Molecular sieve as catalyst

Molecular sieve beads

Molecular sieve catalysis

Molecular sieve catalysts

Molecular sieve catalysts, preparation

Molecular sieve compounds

Molecular sieve dryer

Molecular sieve materials

Molecular sieve materials properties

Molecular sieve membrane

Molecular sieve membrane carbon

Molecular sieve paraffin separation adsorbent

Molecular sieve phosphates, synthesis

Molecular sieve processes

Molecular sieve processing

Molecular sieve silicalite

Molecular sieve structural properties

Molecular sieve suppl

Molecular sieve table, pore diameter

Molecular sieve traps

Molecular sieve zeolites, crystalline

Molecular sieve zeolites, crystalline structures

Molecular sieves

Molecular sieves

Molecular sieves 12-membered ring structures

Molecular sieves 752 Subject

Molecular sieves AIPO

Molecular sieves Terms Links

Molecular sieves analysis

Molecular sieves as adsorbents

Molecular sieves capacity decline with use

Molecular sieves carbon membranes MSCM)

Molecular sieves containing transition

Molecular sieves containing transition metals in the framework

Molecular sieves degassing

Molecular sieves dehydration with

Molecular sieves drying samples

Molecular sieves early investigations

Molecular sieves enamine synthesis

Molecular sieves equilibrium isotherms

Molecular sieves germanium structures

Molecular sieves hydrogen purification with

Molecular sieves mesoporous structures

Molecular sieves phosphates

Molecular sieves physical properties

Molecular sieves pore size

Molecular sieves pore structure

Molecular sieves properties

Molecular sieves silicates

Molecular sieves substituted

Molecular sieves sulfur removal with

Molecular sieves techniques

Molecular sieves water removal

Molecular sieves, addition with

Molecular sieves, addition with Subject

Molecular sieves, chiral metal complex

Molecular sieves, oxygen production

Molecular sieves, pore structure characterization

Molecular sieves, separation

Molecular sieves, separation gases with

Molecular sieves, use for air separation

Molecular sieves, zeolitic

Molecular sieving carbons

Molecular sieving efFect

Molecular sieving properties

Molecular sieving silica

Molecular sieving silica membranes

Molecular sieving temperature effects

Molecular sieving using zeolite

Molecular sieving zeolite membranes

Molecular sieving, definition

Molecular sieving, film-/membrane-base

Molecular, flow 21, sieve

Molecular, generally sieves

Molecular-sieve carbon, pore size

Molecular-sieve carbon, pore size distribution

Molecular-sieve catalysts zeolites

Molecular-sieve chromatography

Molecular-sieve effect

Molecular-sieving carbons, example

New mesoporous molecular sieves

Nickel modified molecular sieves

Niobium containing molecular sieves

Nomenclature, molecular sieve materials

Octahedral molecular sieves

Octahedral molecular sieves (OMS

Of borosilicate molecular sieves

Organic Additives (Templates) in Synthesis of Zeolites and Molecular Sieves

Organic templates molecular sieve synthesis

Organic-functionalized molecular sieve

Other Molecular Sieves

Other Transition Metal-substituted Molecular Sieves

Over SAPO molecular sieves

Oxidation with metal substituted molecular sieve

Oxygen adsorption molecular sieves

PERSPECTIVES IN MOLECULAR SIEVE SCIENCE

Permeation carbon molecular sieve

Phosphorus substitution, SAPO molecular sieves

Pore size, aluminophosphate molecular sieves

Pore system, SAPO molecular sieves

Preparation of Carbon Molecular Sieves (CMS or MSC)

Properties of Molecular Sieves

Protonated from molecular sieve

Redox molecular sieves

Regeneration zeolite molecular sieves

Removal by molecular sieves

Ring size, aluminophosphate molecular sieves

SAPO molecular sieves

SYNTHESIS AND MOLECULAR SIEVES

Selective oxidation with aqueous titanium silicate molecular sieves

Separation mechanisms molecular sieving effect

Separation of Peptides and Proteins by Molecular Sieving

Sharpless reaction molecular sieves

Silica molecular sieves

Silica molecular sieves, isomorphous

Silicalite-1 molecular sieves synthesis

Silicates mesoporous molecular sieves

Silicoaluminophosphate molecular sieves

Situ Microspectroscopy of H-ZSM-5 Molecular Sieves

Size molecular sieving effect

Sorbents carbon molecular sieves

Sorbents molecular sieves

Sorbents zeolite molecular sieves

Space Limitations and Molecular Sieving

Stationary phases molecular sieves

Structural molecular sieves

Structure directing agents , large pore zeolite molecular sieves

Supported zeolite and MOF molecular sieve membranes

Synthesis aluminophosphate molecular sieves

Synthesis molecular sieve zeolite

Synthesis molecular sieves

Synthesis of MeAPO Molecular Sieves

Synthesis of aluminophosphate molecular sieves

Synthesis of mesoporous molecular sieves

Synthesis of molecular sieve

Synthesis of titanium silicate molecular sieves

The Development of Chemistry for Molecular Sieves and Porous Materials

Ti-containing molecular sieves

Titanium silicate molecular sieves

Titanium silicate molecular sieves active sites

Titanium silicate molecular sieves catalytic properties

Titanium silicate molecular sieves epoxidation

Titanium silicate molecular sieves hydroxylations

Titanium silicate molecular sieves oxidation reactions

Titanium silicate molecular sieves synthesis

Titanium-containing molecular sieves

Titanosilicate molecular sieve

Transition metal ions mesoporous molecular sieves

Transition metal-containing molecular sieves

Transport mechanism, membranes molecular sieving

True Molecular Sieving for Small Molecules

True molecular sieving, small

Typical Synthetic Procedures for some Important Molecular Sieves

V-containing molecular sieves

V-molecular sieves

VERY LARGE PORE MOLECULAR SIEVE

Vanadium-containing molecular sieve

Water molecular sieve

Zeolite and molecular sieves

Zeolite and molecular sieves materials

Zeolite molecular sieve film

Zeolite molecular sieves

Zeolite molecular sieving properties

Zeolite-like Molecular Sieves with Intersecting (or Interconnected) Channels

Zeolite-like molecular sieves

Zeolites and Related Molecular Sieves

Zeolites molecular sieve effects

Zeolites redox molecular sieve

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