Search results for "Microporous"
showing 10 items of 94 documents
Sequestering aromatic molecules with a spin-crossover Fe(II) microporous coordination polymer.
2012
All in a spin: A series of three-dimensional porous coordination polymer {Fe(dpe)[Pt(CN)(4)]}⋅G (dpe = 1,2-di(4-pyridyl)ethylene; G = phenazine, anthracene, or naphthalene) exhibiting spin crossover and host-guest functions is reported. The magnetic properties of the framework are very sensitive to the chemical nature (aromatic or hydroxilic solvents) and the size of the included guest molecules.
Sorption of argon and nitrogen on network types of zeolites and aluminophosphates
1991
Abstract Synthetic zeolites and aluminophosphates comprising 10- and 12- membered ring openings, unidimensional and network type of pore systems (MFI, MEL, ERI, LTA, AEL, AFI and FAU) were used as model adsorbents to examine the impact of micropore structure on the sorption properties. Argon and nitrogen were employed as adsorptives. Adsorption measurements were carried out on gravimetric and volumetric sorption devices and also monitored by microcalorimetry. From the low coverage regime of the isotherm Henry's constants and isosteric heats of adsorption were derived. Both quantities allowed the discrimination between 10- and 12- membered ring systems. Unidimensional 10- and 12- membered ri…
High-resolution sorption studies of argon and nitrogen on large crystals of microporous zeolite ZSM-5
1989
High resolution adsorption (HRADS) with argon and nitrogen at 77 K were performed on large crystals of zeolite ZSM-5 using a novel volumetric device. Multi-step isotherms for both adsorptives could be observed for the first time. The micropore filling was followed by low temperature microcalorimetry. Exothermic heats of adsorption were found to be correlated with steps in the adsorption isotherms. Based on results from atom-atom potential energy calculations (AAP) as well as from independent model building it is shown that 24 kinetic adsorbate molecules can be situated in a ZSM-5 unit cell. Localized adsorption is presented as possible filling mechanisms. Experimental results are reasonably…
Influence of a major exposure surface on the development of microporous micritic limestones - Example of the Upper Mishrif Formation (Cenomanian) of …
2017
18 pages; International audience; Microporous platform top limestones of the Cenomanian Mishrif Formation (offshore Qatar) were studied in order to investigate the diagenetic processes associated with the top-Mishrif subaerial unconformity and its influence on the development of microporosity in underlying carbonates. Petrographical and stable isotope results indicate that complex diagenetic changes occurred during subaerial exposure of the Mishrif Formation, including pervasive dissolution and meteoric cementation, as well as neomorphism of the micritic matrix. Micrites at the top of the Mishrif Formation are coarse (i.e. > 2 μm), sub-rounded and very dull luminescent under cathodoluminesc…
Selective CO2 adsorption by a triazacyclononane-bridged microporous metal-organic framework.
2011
Metal-organic frameworks constructed by self-assembly of metal ions and organic linkers have recently been of great interest in the preparation of porous hybrid materials with a wide variety of functions. Despite much research in this area and the large choice of building blocks used to fine-tune pore size and structure, it remains a challenge to synthesise frameworks composed of polyamines to tailor the porosity and adsorption properties for CO(2). Herein, we describe a rigid and microporous three-dimensional metal-organic framework with the formula [Zn(2)(L)(H(2)O)]Cl (L=1,4,7-tris(4-carboxybenzyl)-1,4,7-triazacyclononane) synthesised in a one-pot solvothermal reaction between zinc ions a…
Samplers for VOCs in air based on cyclodextrin–silica hybrid microporous solid phases
2012
Samplers for VOCs in air based on cyclodextrin-silica hybrid microporous solid phases are proposed. The solid phase preparation is very easy and inexpensive. Proposed samplers compared with other solid phases present the advantages of a wider range of operative conditions for VOCs desorption. Samplers are tested based on results for the determination of benzene, toluene, ethylbenzene and o-xylene, m-xylene and p-xylene (BTEX) in air. Operational parameters are optimized and quantitative recovery is obtained using a solid phase from 2-hydroxypropyl-β-cyclodextrin and acetonitrile as the extraction solvent. The recoveries obtained are 89 ± 4%, 90 ± 6%, 91 ± 2%, 87.0 ± 0.9%, 88 ± 4%, and 88 ± …
Microporous hypercrosslinked polystyrene Styrosorb as a restricted access packing in sample clean-up for high performance liquid chromatography. Part…
1993
Styrosorb is a beaded microporous polystyrene with particle sizes between 2 and 4 μm. In spite of hypercrosslinkage the material was seen to swell in organic solvents. The native material is functionalized with Tris-groups at the outer surface of the particles. The average pore diameter was determined as 1.45±0.3 nm from size exclusion data using polystyrene and polyethylene standards in THF. The reversed phase behavior of the restricted access phase Styrosorb was investigated by injection of two test mixtures. Mixture I contained five aromatic amines, mixture II consisted of AmperozideR and four related compounds. The optimum range of mobile phase composition was assessed so that analytes …
Comparative study of degassing membrane modules for the removal of methane from Expanded Granular Sludge Bed anaerobic reactor effluent
2016
Abstract The feasibility of an emergent technology for in situ removal/recovery of methane from the effluent of an Expanded Granular Sludge Bed (EGSB) anaerobic reactor has been studied. For this purpose, the performances of two commercial hollow fibre degassing contactors with different membrane materials – microporous (polypropylene, PP) and non-porous (polydimethylsiloxane, PDMS) – were compared. The influence of water fluxes (Q L /A membrane ranging from 22.6 to 377.4 L h −1 m −2 ), vacuum pressure (140–800 mbar), sweep gas fluxes (Q N2 /A membrane ranging from 0.14 × 10 3 to 4.44 × 10 3 L h −1 m −2 ), and mode of operation (liquid flowing in the lumen side or the shell side) was stu…
Fast detection of water and organic molecules by a change of color in an iron(II) microporous spin-crossover coordination polymer.
2012
Here we present a novel three-dimensional iron(II) spin-crossover porous coordination polymer based on the bis(1,2,4-triazol-4-yl)adamantane (tr(2)ad) ligand and the [Au(CN)(2)](-) metalloligand anions with the formula {Fe(3)(tr(2)ad)(4)[Au(CN)(2))](2)}[Au(CN)(2)](4)·G. The sorption/desorption of guest molecules, water, and five/six-membered-ring organic molecules is easily detectable because the guest-free and -loaded frameworks present drastically distinct coloration and spin-state configurations.
Aspects of the characterization of cloverite by solid-state n.m.r. techniques
1993
Abstract Microporous gallophosphate cloverite has been studied by multinuclear ( 13 C, 19 F, 31 P, 71 Ga) solid-state n.m.r. spectroscopy. An extraordinarily strong quadrupolar coupling is shown to be the reason for a misleading line shape in 71 Ga MAS n.m.r. spectra. Using static 71 Ga n.m.r. spectroscopy, an estimate of the size of this quadrupolar coupling can be obtained. The limitations of the MAS technique for the study of quadrupolar nuclei in sites with very large quadrupolar couplings are addressed.