Role of Mechanical Treatment in Preparation of Multicomponent Bismuth Molybdate Catalyst for Propylene Ammoxidation

1992 ◽  
Vol 57 (5) ◽  
pp. 1028-1032
Author(s):  
Magdy A. Wassel ◽  
Alla K. Khamamedova ◽  
Keikavus Y. Adyamov
Keyword(s):  
Surface Area ◽  
Mechanical Treatment ◽  
Favourable Effect ◽  
Texture Surface ◽  
X Ray ◽  
Multicomponent Bismuth Molybdate ◽  
Propylene Ammoxidation ◽  
Co Precipitation ◽  
Grinding Time

The multicomponent catalyst Mo12Bi1Fe3Co4.5Ni2.5K0.1P0.5Ox/SiO2 (50% w/w) for propylene ammoxidation was prepared by mechanical treatment of the initial components and compared with the catalyst obtained by co-precipitation. Data on its catalytic activity, selectivity and texture (surface area and porosity) are reported. X-Ray study of the samples subjected to mechanical treatment for different times (from 0.5 to 12 h) showed that the treatment leads to changes in phase composition of the catalyst which become more pronounced on prolonged grinding time. The increase of grinding time results also in reduction of the surface area and porosity of the catalysts. Notwithstanding, data obtained demonstrate that mechanical treatment exerts favourable effect on the activity of Fe-Bi-Mo oxide catalysts.

Structural and morphological features of MgO powders. The key role of the preparative starting compound

1998 ◽  
Vol 13 (8) ◽  
pp. 2218-2223 ◽  
Author(s):  
S. Ardizzone ◽  
C. L. Bianchi ◽  
B. Vercelli
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Specific Surface ◽  
Surface Area ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Starting Compound ◽  
Scanning Electron

The present paper reports data concerning magnesia samples obtained by calcination of different precursor salts at different increasing temperatures (873–1253 K). The oxides are characterized by x- ray diffraction, scanning electron microscopy, and N2 adsorption at subcritical temperatures. The samples appear to be composed, at any temperature, of pure periclase with a degree of crystallinity which increases with the temperature of calcination. Morphologically, the products have the shape either of lamellas or of cubes of variable dimensions, depending on the nature and route of preparation of the precursor salts. The variation of the specific surface area and the degree of porosity with the nature of the precursors and the temperature is discussed.

scholarly journals Impact of Oxalate Ligand in Co-Precipitation Route on Morphological Properties and Phase Constitution of Undoped and Rh-Doped BaTiO3 Nanoparticles

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1697 ◽  
Author(s):  
Roussin Lontio Fomekong ◽  
Shujie You ◽  
Francesco Enrichi ◽  
Alberto Vomiero ◽  
Bilge Saruhan
Keyword(s):  
Surface Area ◽  
Oxide Phase ◽  
Solid State Reactions ◽  
Morphological Properties ◽  
Secondary Phases ◽  
X Ray ◽  
Oxalate Ligand ◽  
Oxalate Route ◽  
Co Precipitation ◽  
Synthesized Materials

In order to design and tailor materials for a specific application like gas sensors, the synthesis route is of great importance. Undoped and rhodium-doped barium titanate powders were successfully synthesized by two routes; oxalate route and classic route (a modified conventional route where solid-state reactions and thermal evaporation induced precipitation takes place). Both powders were calcined at different temperatures. X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX) and Brunauer-Emmet-Teller (BET) analyses are employed to identify the phases and polymorphs, to determine the morphology, the chemical composition and the specific surface area of the synthesized materials, respectively. The so-called oxalate route yields pure BaTiO3 phase for undoped samples at 700 °C and 900 °C (containing both cubic and tetragonal structures), while the classic route-synthesized powder contains additional phases such as BaCO3, TiO2 and BaTi2O5. Samples of both synthesis routes prepared by the addition of Rh contain no metallic or oxide phase of rhodium. Instead, it was observed that Ti was substituted by Rh at temperatures 700 °C and 900 °C and there was some change in the composition of BaTiO3 polymorph (increase of tetragonal structure). Heat-treatments above these temperatures show that rhodium saturates out of the perovskite lattice at 1000 °C, yielding other secondary phases such as Ba3RhTi2O9 behind. Well-defined and less agglomerated spherical nanoparticles are obtained by the oxalic route, while the classic route yields particles with an undefined morphology forming very large block-like agglomerates. The surface area of the synthesized materials is higher with the oxalate route than with the classic route (4 times at 900 °C). The presence of the oxalate ligand with its steric hindrance that promotes the uniform distribution and the homogeneity of reactants could be responsible for the great difference observed between the powders prepared by two preparation routes.

Effects of Wet Grinding Process on the Properties of the Ground Diatomite Particles

2010 ◽  
Vol 178 ◽  
pp. 124-128
Author(s):  
Xu Ming Wang ◽  
Yan Xi Deng ◽  
Yan Feng Li
Keyword(s):  
Methylene Blue ◽  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Grinding Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wet Grinding ◽  
Grinding Time

Wet grinding of diatomite was carried out in a stirred mill. The changes in particle size, specific surface area and structure or the particle shape in the wet grinding process were investigated. The adsorption of methylene blue from aqueous solution by the ground diatomite was also studied. X-ray diffraction (XRD), scanning electron microscopy (SEM) and IR spectra were employed to characterize the ground diatomite. The median particle size decreased and the specific surface area increased with the grinding time, an agglomeration phenomenon was not observed during the experimental grinding time. The X-ray diffraction patterns versus grinding time showed that a peak intensity reduction of opal. The results of adsorption of methylene blue onto diatomite indicated the adsorption capacity increases with the increase of grinding time until eventually reaches a constant value.

The Reduction Properties of Hexa Aluminates Substituted by Different Metal Ions for Denitrification System

2013 ◽  
Vol 734-737 ◽  
pp. 2364-2368
Author(s):  
Xiao Guang Ren ◽  
Fu Xia Li ◽  
Peng Li ◽  
Wei Hou
Keyword(s):  
Metal Ions ◽  
Surface Area ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Co Precipitation

In this study, the hexaaluminate catalyst SrMnMAl10O19-δ（M= Cd、Co、Cu 、Fe、Ni、Zn、Zr、Cr and Y）and SrMnFexAl11-xO19-δ(x=1, 2, 4, 6, 8)have been prepared by co-precipitation method. The catalysts were characterized by powder X-ray diffraction (XRD), surface area (BET), hydrogen temperature programmed reduction (H2-TPR). The reduction catalyst properties of hexaaluminate for deNOx were evaluated by using devices of micro-evaluation. The results showed that the CO could remove NOx very well. The hexaaluminate not only have a good catalytic performance, but also can form a complete crystal calcined at 1200 °C for 4 h.

Preparation of High Surface Area Ni-SDC Cermets Using a Surfactant-Assisted Co-Precipitation Method

2006 ◽  
Vol 942 ◽  
Author(s):  
Sang Joon Park ◽  
Tae Wook Eom ◽  
Jae Eun Oh ◽  
Hae Kwang Yang ◽  
Kyung Hwan Kim
Keyword(s):  
Surface Area ◽  
Cetyltrimethylammonium Bromide ◽  
High Surface ◽  
High Surface Area ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Phases ◽  
Co Precipitation ◽  
Surfactant Assisted

ABSTRACTA surfactant-assisted co-precipitation method was employed for obtaining high surface area Ni-SDC with improved structural properties for SOFC applications. In the work, a cationic surfactant, cetyltrimethylammonium bromide(CTAB) was employed with NiCl2, SmCl3 and CeCl3 as precursors and NH4OH as mineralizer. The elimination of surfactants upon calcination gives rise to the formation of high surface area NiO-SDC. When calcined at 600°C, the powders with surface area of 249 m2/g, were obtained and the pore size was 14.45 nm. The powders consist of two phases, the cubic NiO and SDC confirmed with X-ray diffraction identification.

scholarly journals Thermal behavior of ground talc mineral

2008 ◽  
Vol 44 (1) ◽  
pp. 7-17 ◽  
Author(s):  
V. Balek ◽  
J. Subrt ◽  
L.A. Pérez-Maqueda ◽  
M. Benes ◽  
I.M. Bountseva ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Thermal Behavior ◽  
Surface Area ◽  
X Ray Diffraction ◽  
Ground Sample ◽  
X Ray ◽  
Micro Cracks ◽  
Exothermal Effect ◽  
Structure Disorder ◽  
Grinding Time

Microstructure development and thermal behavior of ground talc mineral samples (from locality Puebla de Lillo, Spain) was characterized by X-ray diffraction, scanning electron microscopy(SEM),surface area measurements differential thermal analysis, thermogravimetry and emanation thermal analysis (ETA).A vibratory mill and grinding time 5 min. was used to prepare the ground talc sample. It was found that grinding caused an increase in the surface area of the natural talc from 3 m2g-1 to 110 m2g-1. A decrease of particle size after sample grinding was observed by SEM. The increase of structure disorder of the ground sample and the crystallite size reduction from 40 to 10 nm were determined from the XRD results. ETA results revealed a closing up of surface micro-cracks and healing of microstructure irregularities on heating in the range 200-500?C of both un-ground and ground talc samples. For the ground talc sample a crystallization of non-crystalline phase into orthorhombic enstatite was characterized as by a decrease of radon mobility in the range 785-825?C and by a DTA exothermal effect with the maximum at 830?C. ETA results were used for the assessment of transport properties of the talc samples on heating.

Co-Precipitation Processing of Nanosized (Y,Gd)2O3: Eu Powder and Its Enhanced X-Ray Excited Luminescence

2005 ◽  
Vol 492-493 ◽  
pp. 101-108 ◽  
Author(s):  
Ying Shi ◽  
Ji Yang Chen ◽  
Jian Lin Shi
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Luminescence Intensity ◽  
X Ray ◽  
Ft Ir ◽  
Co Precipitation ◽  
Excited Luminescence

Preparation of nanosized (Y,Gd)2O3:Eu powders by co-precipitation processing is reported. Phase transformation during calcination was studied by means of DTA-TG FT-IR, SEM and XRD in detail. It was found that the morphologies and X-ray excited luminescence of (Y,Gd)2O3:Eu powders were greatly influenced by the precipitants used. The (Y,Gd)2O3:Eu powder resulted from the complex precipitants of NH3•H2O and NH4HCO3 possessed best microstructural features with grain size of about 30nm and specific surface area of 38m2/g after being calcined at 8500C for 2hr, showing a much finer grain and less agglomeration than those from other two precipitation processing. It was demonstrated that nanosized (Y,Gd)2O3:Eu powder from complex precipitant exhibited much higher luminescence intensity at 611nm under excitation of X-ray (70Kev). which might be attributed to less degree of agglomeration among primary grains, decreasing the probability of non-radiation relaxation.

Decontamination of Mercury from Mined Soil using Magnetite Functionalized Quaternary Ammonium Silica (Fe3O4/SAK)

2021 ◽  
Vol 18 (1) ◽  
pp. 88-98
Author(s):  
Ngatijo Ngatijo ◽  
Defia Indah Permatasari ◽  
Faizar Farid ◽  
Restina Bemis ◽  
Heriyanti Heriyanti ◽  
...  
Keyword(s):  
Surface Area ◽  
Quaternary Ammonium ◽  
Mercury Contamination ◽  
Small Scale ◽  
X Ray ◽  
Batch Type ◽  
Morphological Studies ◽  
The Fourier Transform ◽  
Co Precipitation ◽  
Mining Soils

Artisanal small-scale gold mining (ASCGM) has caused mercury contamination. However, efforts to decontaminate mercury from the ex-mining soils are still rare. This study aims to synthesize quaternary ammonium silica functionalized magnetite (Fe3O4/SAK) as a low price, highly available, and quickly separated adsorbent for mercury decontamination from ex-mining soils samples. The synthesis of Fe3O4/SAK and the mercury decontamination process was carried out by the co-precipitation and batch type reactor procedure, respectively. The Fourier Transform-Infra Red (FT-IR) characterization of synthesized Fe3O4/SAK informed the appearance of siloxane, silanol, methyl, methylene, and Fe-O functional groups. Crystal analysis by X-Ray Diffraction (XRD) showed that the typical peaks of SiO2 and Fe3O4 were emerged at 2θ 22.8˚ and 35.52˚, respectively. Morphological studies and elemental analysis using Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX) indicated the successful functionalization Fe3O4 by SAK in the transformation of surface morphology and composition of the main elements, namely C, O, Si, and Fe. The results of characterization using Surface Area Analyzer (SAA) showed that the surface area and pore diameters were 224.98 m2/g and 36.149-38.70 Å, respectively. The optimum results for adsorbing Hg22+ metal ions were obtained at pH 4.0, and the adsorbent mass was 0.1 g. The Fe3O4/SAK has been proven to be an easily separable adsorbent after the mercury decontamination process in ex-mining soil samples with an adsorption efficiency of 43.36% (0.722 mg/g).

scholarly journals Influence of mechanical activation on synthesis of zinc metatitanate

2005 ◽  
Vol 37 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Nebojsa Labus ◽  
Nina Obradovic ◽  
Tatjana Sreckovic ◽  
V. Mitic ◽  
Momcilo Ristic
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Specific Surface ◽  
Mechanical Activation ◽  
Surface Area ◽  
Perovskite Structure ◽  
Mechanical Treatment ◽  
X Ray ◽  
Scanning Electron

Investigations of a ZnO-TiO2 binary oxide mixture during mechanical treatment were mainly focused on obtaining orthotitanate Zn2TiO4 with a spinel structure. Due to the specific way of energy transfer during mechanical treatment using a high-energy ball mill, the system passes through low temperature ZnTiO3 metatitanate phase formation. Mechanical activation was performed on an equimolar ratio mixture of ZnO and TiO2. The anatase phase was previously submitted to heat treatment for achieving a starting mixture rich in a rutile phase. Milling conditions were preset for observing the formation of a low temperature ZnTiO3 phase with a perovskite structure. The powder microstructure was characterized using scanning electron microscopy. A nitrogen gas sorption analyzer with the BET method was used to determine the specific surface area and porosity, indicating changes of powder sample properties during mechanical activation. Also, X ray powder diffractometry was applied to obtain the phase composition. Powders were then pressed into pellets and their compressibility was observed through density changes. According to microstructures obtained by scanning electron microscopy analysis, the system underwent a primary and secondary agglomeration process. Specific surface area measurements supported that conclusion. Compressibility investigations established the difference between compressibility of the non-activated mixture and activated powders. X-ray diffraction analysis revealed that a perovskite structure forms simultaneously with a spinel phase during the process of mechanical activation.

Role of Combined Water for Determining the Mechanical Behaviour of Class C Fly Ash Belite Cements

2010 ◽  
Vol 636-637 ◽  
pp. 1252-1257
Author(s):  
S. Goñi ◽  
A. Guerrero
Keyword(s):  
Mechanical Strength ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Nitrogen Flow Rate ◽  
X Ray ◽  
Technological Characteristics ◽  
Hydrated Products

The physically-chemically bounded water is an important parameter directly related to the gain of mechanical strength during the hydration of cements. In this work, quantitative determinations of the physically - chemically bounded water of two types of belite cements, called FABC-2-W and FABC-2-N, were carried out by means of thermogravimetry analyses during a period of 180 days of hydration. The hydrated products were characterized by X-ray diffraction and BET surface area. Important direct quantitative correlations were obtained between the combined water and technological characteristics of cements such as the compressive mechanical strength or the BET surface area. TG measurements for hydrated FABC-2-W and FABC-2-N cements were carried out in flowing nitrogen on a TGA/SDTA 851 (Mettler) in the temperature range from 25 to 1100°C with heating rate of 10 °C min-1 and nitrogen flow rate of 25 mL min-1. BET surface area was measured using nitrogen adsorption at 77 K, on an ASAP 2010 (Micromeritics).

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