scholarly journals Synthesis of high-silica ZSM-5 with seeds in the presence of ethanol and amine

Cerâmica ◽  
2019 ◽  
Vol 65 (375) ◽  
pp. 378-387
Author(s):  
T. R. D. Mendonça ◽  
J. R. Santos ◽  
L. R. A. Sarmento ◽  
D. C. M. Silva ◽  
O. M. S. Cysneiros ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Organic Compounds ◽  
Nitrogen Adsorption ◽  
Structure Directing Agent ◽  
X Ray ◽  
Synthesis Conditions ◽  
Combined Use ◽  
Cracking Reaction ◽  
High Silica ◽  
Alternative Structure

Abstract The possibility of crystallization of ZSM-5 with high Si/Al ratio was evaluated through the combined use of crystallization seeds and organic compounds that are not conventional directing agents for ZSM-5 (ethanol, methylamine, ethylamine, propylamine, butylamine, isopropylamine and diethylamine) in order to find a less toxic and costly route of synthesis. In addition, the influence of the stirring during the crystallization step on the properties of the ZSM-5 obtained in these synthesis conditions was verified. The obtained zeolites were analyzed by X-ray diffractometry in order to understand the effects of the templates. The analyses of NH3-TPD, nitrogen adsorption, SEM, and TG/DTA were performed for the samples with better crystallinity. The procedure was successfully employed for the synthesis of MFI samples using propylamine as an alternative structure-directing agent. Its mean crystallite size ranged from 23 to 24 nm and was efficient in the cracking reaction of n-hexane.

scholarly journals Characterization of bentonite clay from 'Greda' deposit

2011 ◽  
Vol 5 (2) ◽  
pp. 97-101 ◽  
Author(s):  
Nadezda Stankovic ◽  
Mihovil Logar ◽  
Jelena Lukovic ◽  
Jelena Pantic ◽  
Miljana Miljevic ◽  
...  
Keyword(s):  
Ceramic Industry ◽  
Bentonite Clay ◽  
Nitrogen Adsorption ◽  
Raw Material ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
High Silica ◽  
Representative Samples

Based on mineralogical and technological investigations of the deposit 'Greda' important characteristics of bentonite clay were determined. Representative samples of the deposit were characterized with X-ray diffraction, low-temperature nitrogen adsorption, chemical analysis, differential thermal analysis and scanning electron microscopy. It was determined that the main mineral is montmorillonite and in subordinate quantities kaolinite, quartz and pyrite. The chemical composition generally shows high silica and alumina contents in all samples and small quantities of Fe3+, Ca2+ and Mg2+ cations. Based on technological and mineralogical research, bentonite from this deposit is a high-quality raw material for use in the ceramic industry.

scholarly journals Single Gas Permeance Performance of High Silica SSZ-13 Zeolite Membranes

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 43 ◽  
Author(s):  
Li Liang ◽  
Meihua Zhu ◽  
Le Chen ◽  
Caijun Zhong ◽  
Yiming Yang ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Zeolite Membrane ◽  
Crystallization Time ◽  
Zeolite Membranes ◽  
X Ray ◽  
Synthesis Conditions ◽  
Precursor Synthesis ◽  
Porous Mullite ◽  
High Silica ◽  
The Ideal

Continuous and high silica SSZ-13 zeolite membranes were prepared on porous mullite supports from high SiO2/Al2O3 ratio or aluminum-free precursor synthesis gel. Single gas permeance (CO2 and CH4) of the high silica SSZ-13 zeolite membrane was decreased with the SiO2/Al2O3 ratio in the precursor synthesis gel, while the ideal CO2/CH4 selectivity of the membrane was gradually increased. Moreover, effects of synthesis conditions (such as H2O/SiO2 and RNOH/SiO2 ratios of precursor synthesis gel, crystallization time) on the single gas permeance performance of high silica SSZ-13 zeolite membranes were studied in detail. Medium H2O/SiO2 and RNOH/SiO2 ratios in the initial synthesis gel were crucial to prepare the good CO2 perm-selective SSZ-13 zeolite membrane. When the molar composition of precursor synthesis gel, crystallization temperature and time were 1.0 SiO2: 0.1 Na2O: 0.1 TMAdaOH: 80 H2O, 160 °C and 48 h, CO2 permeance and ideal CO2/CH4 selectivity of the SSZ-13 zeolite membrane were 0.98 × 10−7 mol/(m2·s·Pa) and 47 at 25 °C and 0.4 MPa. In addition, the SiO2/Al2O3 ratio of the corresponding SSZ-13 zeolite was 410 by X-ray fluorescence spectroscopy.

The Synthesis and Photocatalytic Performance of Samarium Doped Mesoporous Titania

2018 ◽  
Vol 876 ◽  
pp. 15-19
Author(s):  
Jian Wen Shi ◽  
Dan Dan Ma ◽  
Ya Jun Zou
Keyword(s):  
Diffuse Reflectance ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Reflectance Spectroscopy ◽  
Mesoporous Titania ◽  
X Ray Diffraction ◽  
Structure Directing Agent ◽  
X Ray

The meso-porous TiO2 and Sm-doped meso-porous TiO2 were synthesized by a sol-gel method. Polyethylene glycol, with different added content, was added as a structure-directing agent. The prepared meso-porous TiO2 was characterized by nitrogen adsorption, X-ray diffraction and ultraviolet-visible diffuse reflectance spectroscopy, and the photocatalytic performance was evaluated by the decomposition of methyl orange. The results revealed that PEG plays a key role in creating porous structure during the heat-treatment. The photocatalytic performance of TiO2 is improved by adding proper content PEG, and Sm-doping can further promote the photocatalytic performance.

Direct Observation of Crystalline Ordering In Naturally Graphitized Carbon Produced by Low Grade Metamorphism

1977 ◽  
Vol 35 ◽  
pp. 162-163
Author(s):  
Thomas R. McKee ◽  
Peter R. Buseck
Keyword(s):  
Crystallite Size ◽  
Sedimentary Rocks ◽  
Carbonaceous Material ◽  
Low Grade ◽  
X Ray ◽  
Graphitized Carbon ◽  
Transmission Electron ◽  
Heat Treated ◽  
Commercial Carbon ◽  
Metamorphic Zone

Sediments commonly contain organic material which appears as refractory carbonaceous material in metamorphosed sedimentary rocks. Grew and others have shown that relative carbon content, crystallite size, X-ray crystallinity and development of well-ordered graphite crystal structure of the carbonaceous material increases with increasing metamorphic grade. The graphitization process is irreversible and appears to be continous from the amorphous to the completely graphitized stage. The most dramatic chemical and crystallographic changes take place within the chlorite metamorphic zone.The detailed X-ray investigation of crystallite size and crystalline ordering is complex and can best be investigated by other means such as high resolution transmission electron microscopy (HRTEM). The natural graphitization series is similar to that for heat-treated commercial carbon blacks, which have been successfully studied by HRTEM (Ban and others).

Synthesis of dispersed mesoporous powders solid solution Zr0.88Ce0.12O2 for catalyst carrier of the conversion of methane to synthesis –gas

2020 ◽  
pp. 73-83
Author(s):  
L. V. Morozova ◽  
◽  
I. A. Drozdova ◽  
Keyword(s):  
Solid Solution ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Primary Crystal ◽  
X Ray ◽  
Catalyst Carrier ◽  
Conversion Of Methane ◽  
Deposition Processes ◽  
Zirconia Oxide ◽  
Coprecipitation Of Hydroxides

The xerogels in the system 0.88 mol.% ZrO2 − 0.12 mol.% CeO2 were obtained by the method of coprecipitation in a neutral (pH = 7) and slightly alkaline (pH = 9) medium under the influence of ultrasound with the size of the agglomerates 70 – 230 nm. It is shown that the coprecipitation of hydroxides of zirconium and cerium at pH = 9 with the use of ultrasonic treatment facilitates the formation of a primary crystal is symbolic of the particles in the xerogel, whose size is ~ 5 nm, whereas the xerogel synthesized in a neutral environment consists only of the x-ray amorphous phase. The effect of pH-precipitation on deposition processes of dehydration of the xerogels and crystallization solid solution based on zirconia oxide in the metastable pseudocubic modification (с′-ZrO2) was discovered. It was found that in the temperature range 500 – 800 °C there is a phase transition с′-ZrO2 → t-ZrO2, the size of the crystallites of the formed tetragonal solid solutions is 8 and 11 nm. The method of low-temperature nitrogen adsorption were investigated dispersion properties and characteristics of the pore structure of the powders of the solid solution Zr0.88Ce0.12O2. It is determined that the specific surface area of t-ZrO2 samples obtained after firing at 800 °C is 117 and 178 m2/g, the total pore volume reaches 0.300 − 0.325 cm3/g, the pore size distribution is monomodal and is in the range of 2 − 8 nm. The effect of thermal “aging” at a temperature of 800 °C (40 h) on the structure and dispersion of the solid solution t-ZrO2 powders was studied.

Preparation and properties of green rust type substances

1987 ◽  
Vol 52 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Jaroslav Vinš ◽  
Jan Šubrt ◽  
Vladimír Zapletal ◽  
František Hanousek
Keyword(s):  
Chemical Composition ◽  
Electron Diffraction ◽  
Green Rust ◽  
X Ray ◽  
Synthesis Conditions ◽  
Diffraction Patterns

A method has been worked out for the reproducible preparation of Green Rust substances involving SO42-, Cl-, Br-, and I- anions. The chemical composition of the substances prepared has been followed in dependence on the synthesis conditions. The powder X-ray and electron diffraction patterns and infrared and Moessbauer spectra have been measured and discussed.

scholarly journals Quartz Crystallite Size and Moganite Content as Indicators of the Mineralogical Maturity of the Carboniferous Chert: The Case of Cherts from Eastern Asturias (Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Archaeological Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Infrared And Raman Spectroscopy ◽  
First Time ◽  
Geological Formations

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.

scholarly journals Combustion and gasification characteristics of low-temperature pyrolytic semi-coke prepared through atmosphere rich in CH4 and H2

2021 ◽  
Vol 10 (1) ◽  
pp. 189-200
Author(s):  
Yuan She ◽  
Chong Zou ◽  
Shiwei Liu ◽  
Keng Wu ◽  
Hao Wu ◽  
...  
Keyword(s):  
Functional Groups ◽  
Chemical Structure ◽  
Nitrogen Adsorption ◽  
Inhibitory Effect ◽  
X Ray ◽  
Coke Reactivity ◽  
Reducing Gas ◽  
Reactivity Indexes ◽  
Infrared Spectrometer ◽  
Reducing Gases

Abstract Thermoanalysis was used in this research to produce a comparative study on the combustion and gasification characteristics of semi-coke prepared under pyrolytic atmospheres rich in CH4 and H2 at different proportions. Distinctions of different semi-coke in terms of carbon chemical structure, functional groups, and micropore structure were examined. The results indicated that adding some reducing gases during pyrolysis could inhibit semi-coke reactivity, the inhibitory effect of the composite gas of H2 and CH4 was the most observable, and the effect of H2 was higher than that of CH4; moreover, increasing the proportion of reducing gas increased its inhibitory effect. X-ray diffractometer and Fourier-transform infrared spectrometer results indicated that adding reducing gases in the atmosphere elevated the disordering degree of carbon microcrystalline structures, boosted the removal of hydroxyl- and oxygen-containing functional groups, decreased the unsaturated side chains, and improved condensation degree of macromolecular networks. The nitrogen adsorption experiment revealed that the types of pore structure of semi-coke are mainly micropore and mesopore, and the influence of pyrolytic atmosphere on micropores was not of strong regularity but could inhibit mesopore development. Aromatic lamellar stack height of semi-coke, specific surface area of mesopore, and pore volume had a favorable linear correlation with semi-coke reactivity indexes.

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