Synthesis and Structural Characterization of Organically-Modified Microporous Silicates

1998 ◽  
Vol 519 ◽  
Author(s):  
F. Babonneau ◽  
L. Leite ◽  
S. Fonlupt ◽  
F. Ribot ◽  
L. Bergogne ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Nitrogen Adsorption ◽  
Type I ◽  
Silicate Phase ◽  
Organically Modified Silicates ◽  
Bet Method ◽  
Organically Modified ◽  
Acidic Conditions ◽  
Hexagonally Ordered

AbstractOrganically-modified silicates have been synthesized from RSi(OEt)3 (R = CH3, C2H5, C8H17, CH2=CH, C6H5) and TEOS under acidic conditions, in the presence of cethyltrimethylammonium (CTAB). The introduction of RSiO1.5 units with R/Si =0.2, affects the ordering of the expected hexagonal silicate phase, except when R = C6H5. The sample containing phenyl functions was thus submitted to surfactant extraction; calcination at 350°C appears to be more efficient, and less disruptive for the network ordering than a washing procedure in ethanol. Nitrogen adsorption measurements on the hexagonally ordered calcined sample that still contains phenyl groups, yields a type I isotherm, typical of a microporous solid. BET method leads to a surface area of 1000 m2/g and a pore volume of 0.32 cm3/g.

Solvent-free dynamic nuclear polarization enhancements in organically modified mesoporous silica

2021 ◽  
Author(s):  
Marcos de Oliveira Jr. ◽  
Kevin Herr ◽  
Martin Brodrecht ◽  
Nadia Berenice Haro-Mares ◽  
Till Wissel ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Porous Materials ◽  
Structural Characterization ◽  
Dynamic Nuclear Polarization ◽  
High Field ◽  
Nuclear Polarization ◽  
Organically Modified ◽  
Field Dynamic ◽  
Free Dynamic

High-field Dynamic Nuclear Polarization is a powerful tool for the structural characterization of species on the surface of porous materials or nanoparticles. For these studies the main source of polarization...

scholarly journals Synthesis and characterization of biomorphic CeO2 obtained by using egg shell membrane as template

2014 ◽  
Vol 8 (2) ◽  
pp. 81-85 ◽  
Author(s):  
Marija Prekajski ◽  
Biljana Babic ◽  
Dusan Bucevac ◽  
Jelena Pantic ◽  
Jelena Gulicovski ◽  
...  
Keyword(s):  
Water Solution ◽  
New Technology ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Shell Membrane ◽  
Bet Method ◽  
Egg Shell Membrane ◽  
Egg Shell ◽  
Chicken Eggs

A new technology based on bio-templating approach was proposed in this paper. Egg-shell membrane (ESM) has been employed as a natural biotemplate. Fibrous oxide ceramics was prepared by wet impregnation of biological template with water solution of cerium nitrate. The template was derived from membranes of fresh chicken eggs. Repeated impregnation, pyrolysis and final calcination in the range of 600 to 1200?C in air resulted in template burnout and consolidation of the oxide layers. At low temperatures, the obtained products had structure which corresponded to the negative replication of biological templates. Unique bio-morphic CeO2 microstructures with interwoven networks were synthesized and characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), whereas low-temperature nitrogen adsorption (BET) method was used in order to characterize porous properties.

scholarly journals Micro-structural Characterization of Inorganic Cryptomelane Nanomaterials Synthesized by Use of Controlled O2 and Cold Aging in Acidic Conditions

2006 ◽  
Vol 12 (S02) ◽  
pp. 740-741
Author(s):  
L Ma ◽  
T Hartmann ◽  
MA Cheney ◽  
N Birkner
Keyword(s):  
Structural Characterization ◽  
Acidic Conditions

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

Preparation and Characterization of Catalysts Fe/SBA-15 for Fischer Tropsch Synthesis

2014 ◽  
Vol 805 ◽  
pp. 678-683
Author(s):  
Ângela da Costa Nogueira ◽  
Jocielys Jovelino Rodrigues ◽  
Liliane Andrade Lima ◽  
Meiry Glaúcia Freire Rodrigues
Keyword(s):  
Nitrogen Adsorption ◽  
Tropsch Synthesis ◽  
X Ray Diffraction ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
X Ray ◽  
Acidic Conditions ◽  
Diffraction Peaks ◽  
Adsorption Desorption

In this study catalysts Fe/SBA-15 were prepared for Fischer-Tropsch Synthesis. SBA-15 samples were synthesized under acidic conditions using triblock copolymer Pluronic as a template and tetraethyl orthosilicate as a silica source.The molar composition was: 1.0 TEOS: 0017 P123: 8.14 HCl: 168 H2O. Fe/SBA-15 catalysts with different iron loading (15 wt. % and 20 wt. %) were prepared by wetness impregnation of relative SBA-15 with the desired amount of aqueous iron nitrate. The obtained catalyst were characterized by X ray diffraction (XDR), nitrogen adsorption-desorption and energy dispersive X-ray spectrometry (EDX). After impregnation of Fe the XRD profiles were almost unchanged and exhibited the high diffraction peaks of SBA-15 at low angles. The analysis of nitrogen adsorption-desorption was observed that the values of specific surface area decreased as the concentration of metal impregnated increased. And by the EDX analysis verified that the iron contents obtained are close to nominal levels of iron.

Structural characterization of pectin-bismuth complexes and their aggregation in acidic conditions

2020 ◽  
Vol 154 ◽  
pp. 788-794 ◽  
Author(s):  
Wen-xin Jiang ◽  
Jun-Ru Qi ◽  
Jin-song Liao ◽  
Zhi-li Wan ◽  
Wan-ling Liang ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Acidic Conditions

Structural characterization of hexameric shell proteins from two types of choline-utilization bacterial microcompartments

2021 ◽  
Vol 77 (9) ◽  
Author(s):  
Jessica M. Ochoa ◽  
Oscar Mijares ◽  
Andrea A. Acosta ◽  
Xavier Escoto ◽  
Nancy Leon-Rivera ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Building Blocks ◽  
Type I ◽  
Type Ii ◽  
Protein Subunits ◽  
Bacterial Microcompartments ◽  
Bacterial Microcompartment ◽  
Glycyl Radical ◽  
Shell Proteins

Bacterial microcompartments are large supramolecular structures comprising an outer proteinaceous shell that encapsulates various enzymes in order to optimize metabolic processes. The outer shells of bacterial microcompartments are made of several thousand protein subunits, generally forming hexameric building blocks based on the canonical bacterial microcompartment (BMC) domain. Among the diverse metabolic types of bacterial microcompartments, the structures of those that use glycyl radical enzymes to metabolize choline have not been adequately characterized. Here, six structures of hexameric shell proteins from type I and type II choline-utilization microcompartments are reported. Sequence and structure analysis reveals electrostatic surface properties that are shared between the four types of shell proteins described here.

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