scholarly journals Characterization of Manganese Oxide/Alumina Catalysts

1995 ◽  
Vol 12 (3) ◽  
pp. 221-229 ◽  
Author(s):  
S.A. El-Hakam
Keyword(s):  
Manganese Oxide ◽  
Calcination Temperature ◽  
Manganese Content ◽  
Textural Properties ◽  
Catalytic Decomposition ◽  
Experimental Conditions ◽  
Surface Areas ◽  
Ft Ir ◽  
Mn Content ◽  
Alumina Catalysts

The effect of heat treatment of manganese oxide/alumina catalysts of various manganese content on the structural and textural properties and the catalytic decomposition of hydrogen peroxide were investigated. The FT-IR results have shown that depending on the calcination temperature and metal loading MnO2 and MnO3 are formed on the investigated samples. No spinel structure was detected under the experimental conditions. The surface areas were found to decrease with increasing calcination temperature and metal content up to 30 wt.% Mn. The mean pore radius increased with both calcination temperature and Mn content. The rate of catalytic decomposition of H2O2 was found to depend on the pH, the calcination temperature and the state of Mn on the catalyst surface.

Fabrication of Mesoporous ZrO2 by Using Rosin-Based Quaternary Ammonium Salt

2011 ◽  
Vol 239-242 ◽  
pp. 3257-3261 ◽  
Author(s):  
Peng Wang ◽  
Zhen Dong Zhao ◽  
Li Zhi He ◽  
Liang Wu Bi ◽  
Yu Xiang Chen
Keyword(s):  
Ammonium Salt ◽  
Significant Influence ◽  
Quaternary Ammonium ◽  
Quaternary Ammonium Salt ◽  
High Surface ◽  
Textural Properties ◽  
Precipitation Method ◽  
Adsorption And Desorption ◽  
Surface Areas ◽  
Ft Ir

Mesoporous zirconias were prepared by precipitation method using rosin-based quaternary ammonium salt as a directing agent. The samples were characterized by means of XRD, FT-IR and N2-adsorption and desorption measurements. The phase of precursors was amorphous, and well crystallized tetragonal zirconias were obtained after the calcination at 450 °C. The synthesized mesoporous zirconias possessed high surface areas ranging from 183.56 to 203.87 m2g-1and big pore diameters varying from 6.27 to 7.58 nm. The content of the rosin-based quaternary ammonium salt had significant influence on the textural properties of the mesoporous zirconias. Surface areas, pore volumes and pore diameters of the mesoporous zirconias decreased when increasing the surfactant dosage.

scholarly journals Influence of the preparation conditions on the synthesis, structure and thermal properties of LaSrCo1-xMnxO4

2006 ◽  
Vol 71 (6) ◽  
pp. 685-693 ◽  
Author(s):  
H. Zhong ◽  
X.R. Zeng
Keyword(s):  
Calcination Temperature ◽  
Mixed Oxides ◽  
Manganese Content ◽  
Binding Energies ◽  
Type Structure ◽  
Characteristic Peak ◽  
Preparation Conditions ◽  
Mn Content ◽  
Perovskite Type ◽  
Perovskite Type Structure

A series of LaSrCo1-xMnxO4 (x=0.1, 0.3, 0.5) mixed oxides with a perovskite-type structure were successfully synthesized at fairly low temperatures in air by the decompositon of amorphous citric and ethylene diamine tetraacetic acid complexes. The obtained mixed oxides were characterized by means of XRD, BET, DTA, DTG, XPS analyses. The results show that the precursor can be completely decomposed into oxide at temperatures below 500?C. The decomposed species equisisted of LaSrCo1-xMnxO4 mixed oxides and formed a perovskite-type structure after calcination at 650?C for 6h. The influence of the calcination temperature on the particle size, the microstrain density and the specific surface area was much more significant than that of the calcination time. The intensity of the characteristic peak of Co2+ decresed with increasing manganese content in the LaSrCo1-xMnxO4 (x=0.1, 0.3, 0.5) mixed oxides. The binding energies of Mn 2p3/2 in the mixed oxides reveal that themanganese wasmainly in the Mn3+ state, which indicates that the influence of the calcination temperature and Mn content on the binding energies of Mn 2p3/2 was very weak.

Effect of Calcination Temperature on Nickel/Alumina Catalysts

1992 ◽  
Vol 57 (10) ◽  
pp. 2073-2077 ◽  
Author(s):  
Khaliq Ahmed ◽  
Pronab Mistry
Keyword(s):  
Crystallite Size ◽  
Calcination Temperature ◽  
Hydrogen Adsorption ◽  
Nitrogen Adsorption ◽  
Nickel Catalysts ◽  
Surface Areas ◽  
Different Temperatures ◽  
Supported Nickel Catalysts ◽  
Alumina Catalysts

Alumina-supported nickel catalysts prepared by the methods of impregnation and coprecipitation and heated at four different temperatures showed that the optimal calcination temperature for both types of catalysts lies in the region of 623-673 K. Crystallite size measurements by XRD revealed that coprecipitated samples have larger crystallites than the impregnated samples. The total surface areas measured by nitrogen adsorption and the results of metal area measurements made by hydrogen adsorption are in agreement with the crystallite size results.

scholarly journals Characterization and Catalytic Behaviour of Co3(PO4)2–AlPO4 Catalysts

1998 ◽  
Vol 16 (4) ◽  
pp. 285-293 ◽  
Author(s):  
M.R. Mostafa ◽  
F.Sh. Ahmed
Keyword(s):  
Pore Radius ◽  
Surface Acidity ◽  
Total Pore Volume ◽  
Textural Properties ◽  
Acid Sites ◽  
Adsorption Of Nitrogen ◽  
Amorphous Structures ◽  
Ft Ir ◽  
Catalytic Behaviour ◽  
The Mean

Co3(PO4)2, AlPO4 and the binary system Co3(PO4)2-AlPO4 with different compositions were prepared by the coprecipitation method. The structural properties of these samples were determined using XRD, DTA and FT-IR techniques. The textural properties were determined from the adsorption of nitrogen at 77 K. The surface acidity was measured by a calorimetric titration method. The samples were tested as catalysts in the dehydration of ethanol and isopropanol using a pulse microcatalytic technique. The data obtained from XRD and FT-IR indicate the amorphous structures of the prepared catalysts. An increase in Co3(PO4)2 content led to a decrease in the surface area and in the total pore volume and an increase in the mean pore radius. The surface acidity of the catalyst depends on the chemical composition; the surface acidity increased with an increase in the AlPO4 content. The dehydration temperature and the distribution of acid sites are important parameters in determining the selectivity and activity of the catalyst.

scholarly journals Removal of anionic surfactants by sorption onto Aminated Mesoporous Carbon

2013 ◽  
Vol 19 (3) ◽  
pp. 347-357 ◽  
Author(s):  
S.E. Moradi ◽  
J. Khodaveisy ◽  
R. Dashti
Keyword(s):  
Contact Time ◽  
Mesoporous Carbon ◽  
Anionic Surfactants ◽  
Textural Properties ◽  
Nitrogen Adsorption ◽  
Langmuir Model ◽  
Carbon Adsorbents ◽  
Solution Ph ◽  
Batch Mode ◽  
Ft Ir

Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before release to the environment or delivery for public use. In the present work, the removal of anionic surfactants, benzene sulfonate (BS), p-toluene sulfonate (TS) and 4-octylbenzene sulfonate (OBS) from water by adsorption onto Amino modified mesoporous carbon (AMC) were studied. The AMC surface chemistry and textural properties was characterized by nitrogen adsorption, XRD and FT-IR analyses. Experiments were conducted in batch mode with the variables such as amount of contact time, solution pH, dose of adsorbent and temperature. Finally, the adsorption isotherms of anionic surfactants on mesoporous carbon adsorbents were in agreement with a Langmuir model. AMC has shown higher anionic surfactants adsorption capacity than the untreated mesoporous carbon, which can explain by strong interaction between anionic surfactant and cationic surface of adsorbent.

Synthesis and Properties of Nitrogen-Doped Mesoporous Carbon Materials Obtained by Templating of SBA-15 with Melamine-Formaldehyde Resin

2012 ◽  
Vol 554-556 ◽  
pp. 778-782 ◽  
Author(s):  
Chao Liu ◽  
Yong Qi Hu ◽  
Yi Feng Yu ◽  
Yue Zhang ◽  
Yan Yan Wang ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Mesoporous Carbon ◽  
Carbon Materials ◽  
Textural Properties ◽  
Formaldehyde Resin ◽  
Melamine Formaldehyde ◽  
X Ray ◽  
Nitrogen Doped ◽  
Surface Areas ◽  
Mesoporous Carbon Materials

Nitrogen-doped mesoporous carbon materials have been synthesized by using melamine-formaldehyde resin as carbon precursor and SBA-15 as a removable template. The structure of the materials was investigated by X-ray diffraction, BET specific surface area analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. X-ray and BET studies confirmed that a pore nanostructure is inherited from the silica templates. Fourier transform infrared spectroscopy analysis showed N atoms are strongly bonded in the carbon structure in heterocycles or nitrile functions. These mesoporous nitrogen-doped carbon materials exhibits textural properties with BET surface areas ranging between 400 and 600 m2/g and uniform pore size(3.9 nm). The mechanism of carbonization process is studied by thermogravimetric analysis. The ratio of melamine/formaldehyde plays an important role during the carbonization process for the surface areas and textural properties, and element analysis reveals that the nitrogen content of the mesoporous carbon materials is as high as 10wt%.

scholarly journals Optimization Preparation of Indium Tin Oxide Nanoparticles via Microemulsion Method Using Orthogonal Experiment

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1387
Author(s):  
Zhucheng Jiang ◽  
Ting Liu ◽  
Xiaoyu Zhai ◽  
Jiaxiang Liu
Keyword(s):  
Calcination Temperature ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Orthogonal Experiment ◽  
Transparent Conducting Oxide ◽  
Molar Ratio ◽  
Experimental Conditions ◽  
Microemulsion Method ◽  
Low Resistivity ◽  
Ito Nanoparticles

Indium tin oxide (ITO), an experimentally friendly transparent conducting oxide (TCO), has attracted great attention in the photoelectric field due to its intrinsically low resistivity and high transparency. In this work, the experimental conditions of preparing ITO nanoparticles using the microemulsion method were optimized by an orthogonal experiment. The optimal experimental conditions were obtained: mass ratio of the surfactant (AEO-3, MOA-5), a co-surfactant (n-propyl alcohol) of 5:3, molar ratio of indium and ammonia of 1:20, calcination temperature of 700 °C and calcination time of 4 h. Subsequently, the influence from process variables on the resistivity was researched systematically. The results demonstrated that the calcination temperature had a great effect on the resistivity; the resistivity reduced from 11.28 to 2.72 Ω·cm with the increase in the calcination temperature from 500 to 700 °C. Ultimately, ITO nanoparticles were prepared and systematically characterized under the optimal experimental conditions. The particles with a size of 60 nm were attributed to the cubic ITO crystal phase and showed low resistivity of 0.3675 Ω·cm. Significantly, ITO nanoparticles with low resistivity were obtained using the microemulsion method, which has potential application in the field of ITO nanoparticle preparation.

scholarly journals Adsorption of strontium on different sodium-enriched bentonites

2017 ◽  
Vol 82 (4) ◽  
pp. 449-463 ◽  
Author(s):  
Sanja Marinovic ◽  
Marija Ajdukovic ◽  
Natasa Jovic-Jovicic ◽  
Tihana Mudrinic ◽  
Bojana Nedic-Vasiljevic ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Adsorption Capacity ◽  
Textural Properties ◽  
X Ray Diffraction ◽  
Order Model ◽  
Surface Areas ◽  
Alkaline Conditions ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Ph Range

Bentonites from three different deposits (Wyoming, TX, USA and Bogovina, Serbia) with similar cation exchange capacities were sodium enriched and tested as adsorbents for Sr2+ in aqueous solutions. X-Ray diffraction analysis confirmed successful Na-exchange. The textural properties of the bentonite samples were determined using low-temperature the nitrogen physisorption method. Significant differences in the textural properties between the different sodium enriched bentonites were found. Adsorption was investigated with respect to adsorbent dosage, pH, contact time and the initial concentration of Sr2+. The adsorption capacity increased with pH. In the pH range from 4.0?8.5, the amount of adsorbed Sr2+ was almost constant but 2?3 times smaller than at pH ?11. Further experiments were performed at the unadjusted pH since extreme alkaline conditions are environmentally hostile and inapplicable in real systems. The adsorption capacity of all the investigated adsorbents toward Sr2+ was similar under the investigated conditions, regardless of significant differences in the specific surface areas. It was shown and confirmed by the Dubinin?Radushkevich model that the cation exchange mechanism was the dominant mechanism of Sr2+ adsorption. Their developed microporous structures contributed to the Sr2+ adsorption process. The adsorption kinetics obeyed the pseudo-second-order model. The isotherm data were best fitted with the Langmuir isotherm model.

scholarly journals Vitamin D and manganese in the nutrition of the chick

1967 ◽  
Vol 21 (3) ◽  
pp. 507-512 ◽  
Author(s):  
R. Hill
Keyword(s):  
Vitamin D ◽  
Oral Dose ◽  
Manganese Content ◽  
Whole Body ◽  
Mn Content

1. In two experiments with chicks given diets of different manganese content, the effects of vitamin D on the Mn contents of bone and liver and on the retention of 54Mn in bone, liver and the whole body were determined.2. Vitamin D slightly increased the Mn content of dry fat-free bone but the proportion of Mn to ash remained unchanged and the Mn content of bone was influenced much more by the level of dietary Mn than by the presence of vitamin D.3. Vitamin D, when given over a 3-week period, increased slightly the Mn content of the liver, but again the level of dietary Mn had a greater effect than the presence of vitamin D.4. The retention of an oral dose of 54Mn was not uniformly influenced by vitamin D, but in birds given the hign-Mn diet retention was reduced by vitamin D, indicating a decrease in the turnover of Mn.

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