scholarly journals Phase Composition of Ni/Mg1−xNixO as a Catalyst Prepared for Selective Methanation of CO in H2-Rich Gas

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Mengmeng Zhang ◽  
Hongwei Ma ◽  
Zhiming Gao
Keyword(s):  
Phase Composition ◽  
Calcination Temperature ◽  
Rietveld Method ◽  
Minor Amount ◽  
X Ray Diffraction ◽  
Co Conversion ◽  
Method Effects ◽  
Temperature Programmed ◽  
A Minor ◽  
Supported Ni

Supported Ni catalysts Ni/Mg1−xNixO were prepared by reducing samples NiO-MgO in H2/N2mixture gas at 500°C~800°C for selective methanation of CO in H2-rich gas (CO-SMET). The samples NiO-MgO were obtained by heating water slurry of MgO and Ni(NO3)2in a rotary evaporator at 80°C and a final calcination in air at 400°C~800°C. X-ray diffraction (XRD) and temperature programmed reduction (TPR) measurements demonstrate that the samples NiO-MgO were composed of solid solution Mg1−yNiyO as the main phase and a minor amount of NiO at calcination temperature of 400°C, and amount of the NiO was decreased as calcination temperature increased. Phase composition of the catalysts Ni/Mg1−xNixO was estimated by the Rietveld method. Effects of reduction temperature, feed Ni/Mg ratio, and calcination temperature on phase composition and catalytic activity of the catalysts were investigated. It is clear that CO conversion was generally enhanced by an increased amount of metallic Ni of the catalysts.

Application of the Rietveld method to quantitative analysis of impurities in synthetic diamond powder

2004 ◽  
Vol 19 (2) ◽  
pp. 141-144 ◽  
Author(s):  
Rashmi ◽  
Nahar Singh ◽  
A. K. Sarkar
Keyword(s):  
Phase Composition ◽  
Quantitative Analysis ◽  
Synthetic Diamond ◽  
Rietveld Method ◽  
Diamond Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Content ◽  
A Minor ◽  
Synthetic Diamond Powder

Synthetic diamonds are an important class of industrial material. During synthesis impurities may get introduced into diamond. Identification and quantification of impurities is important as they affect the properties and suitability of the diamonds for their application. Impurities in an industrial synthetic diamond powder sample were analyzed by X-ray diffraction (XRD) and also by chemical methods. X-ray diffraction pattern showed diamond as the major phase and α-iron as a minor phase. Quantitative analysis of crystalline phases was done by performing Rietveld refinement of the XRD profile. Chemical analysis showed the presence of several other impurities as well, though in small amounts. It was considered that the impurities other than iron were in amorphous form and an estimate of the amorphous content was made on this basis. Relative phase composition of diamond and iron as estimated by XRD were corrected for the amorphous content to obtain absolute phase composition.

scholarly journals Contributions to the stereochemistry of zirconium oxysalts—part III: syntheses and crystal structures of M2+Zr(SO4)3 with M = Mg, Mn, Co, Ni, Zn and Cd, and a note on (Fe3+,2+,Zr)2(SO4)3 and Fe2(SO4)3

2019 ◽  
Vol 150 (11) ◽  
pp. 1877-1892
Author(s):  
Gerald Giester ◽  
Dominik Talla ◽  
Manfred Wildner
Keyword(s):  
Mixed Valence ◽  
Structure Type ◽  
Minor Amount ◽  
The Novel ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Space Group ◽  
A Minor ◽  
Zirconium Oxysalts ◽  
Oxygen Bond

Abstract The novel compounds M2+Zr(SO4)3 with M = Mg, Mn, Co, Ni, Zn, and Cd as well as (Fe3+,2+,Zr)2(SO4)3 were synthesized at mild hydrothermal conditions (Teflon-lined stainless steel vessels, 220 °C) from the mixtures of Zr2O2(CO3)(OH)2, the respective M2+(SO4)·nH2O hydrated salts, H2SO4 and a minor amount of water. Crystals up to several tenths of a mm in size were obtained within a few days and studied at 200 K by single-crystal X-ray diffraction techniques. All these compounds belong to the structure type of monoclinic Fe2(SO4)3; they are either isotypic in space group P21/n (No. 14), Z = 4, i.e. M2+Zr(SO4)3 with M = Mn, Co, Ni, Zn, and Cd as well as the mixed valence sulfate (Fe3+,2+,Zr)2(SO4)3 or in the case of MgZr(SO4)3, closely related but with a larger unit cell, in space group Pc and Z = 8. The framework of the monoclinic Fe2(SO4)3 structure is characterized by two types of isolated Fe3+O6 octahedra, corner-linked with three types of sulfate groups. In the isotypic M2+Zr(SO4)3 series, the Fe3+ atom on the Fe(1) position is substituted by Zr4+ while M2+ ions occupy the Fe(2) site in the ferric sulfate structure type. Mean cation-oxygen bond lengths (S[4]: 1.462–1.472 Å; Zr[6]: 2.053–2.060 Å as well as M2+–O distances) are generally rather short, but still within the range reported in literature. Graphic abstract

Preparation and Ultra-Deep Hydrorefining Performance of Ni-P/Al2O3-ZrO2 Catalysts

2011 ◽  
Vol 236-238 ◽  
pp. 724-727
Author(s):  
Feng Li ◽  
Hua Song ◽  
Hua Yang Zhang
Keyword(s):  
Chemical Precipitation ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Thiophene Hydrodesulfurization ◽  
Composite Oxides ◽  
Temperature Programmed ◽  
Supported Ni

A series of Al2O3-ZrO2 (AZ-X) composite oxides with different ZrO2 contents were prepared by a chemical precipitation method. Ni-P/AZ-X catalysts were prepared by temperature-programmed reduction. The supports and catalysts were extensively characterized by X-ray diffraction (XRD) and BET. The effects of support composition and P/Ni molar ratios on the catalytic performance of the catalysts were investigated by thiophene hydrodesulfurization (HDS) and pyridine hydrodenitrogenation (HDN). In comparison with Al2O3, Al2O3-ZrO2 (20 wt% ZrO2) composite oxide supported Ni-P catalyst exhibited higher activity and the activities of HDS and HDN increased by 7.5 % and 11.1 %, respectively. Studies of Ni-P/AZ-X catalysts with varying initial P/Ni molar ratios indicated that oxidic precursors with molar ratios of P/Ni = 2/1 yielded catalyst containing phase-pure Ni2P which exhibited optimal activity.

scholarly journals Promotion Effect of CaO Modification on Mesoporous Al2O3-Supported Ni Catalysts for CO2Methanation

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Wen Yang ◽  
Yanyan Feng ◽  
Wei Chu
Keyword(s):  
Surface Coverage ◽  
Temperature Programmed Desorption ◽  
Impregnation Method ◽  
Nio Nanoparticles ◽  
X Ray Diffraction ◽  
Ni Catalysts ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption ◽  
Supported Ni

The catalysts Ni/Al2O3and CaO modified Ni/Al2O3were prepared by impregnation method and applied for methanation of CO2. The catalysts were characterized by N2adsorption/desorption, temperature-programmed reduction of H2(H2-TPR), X-ray diffraction (XRD), and temperature-programmed desorption of CO2and H2(CO2-TPD and H2-TPD) techniques, respectively. TPR and XRD results indicated that CaO can effectively restrain the growth of NiO nanoparticles, improve the dispersion of NiO, and weaken the interaction between NiO and Al2O3. CO2-TPD and H2-TPD results suggested that CaO can change the environment surrounding of CO2and H2adsorption and thus the reactants on the Ni atoms can be activated more easily. The modified Ni/Al2O3showed better catalytic activity than pure Ni/Al2O3. Ni/CaO-Al2O3showed high CO2conversion especially at low temperatures compared to Ni/Al2O3, and the selectivity to CH4was very close to 1. The high CO2conversion over Ni/CaO-Al2O3was mainly caused by the surface coverage by CO2-derived species on CaO-Al2O3surface.

Effects of Fuel Content and Calcination Procedure on Phase Composition and Microstructure of LiMn2O4 Prepared by Solution Combustion Synthesis

2008 ◽  
Vol 368-372 ◽  
pp. 296-298 ◽  
Author(s):  
Jun Ming Guo ◽  
Gui Yang Liu ◽  
Jie Liu ◽  
De Wei Guo ◽  
Ke Xin Chen ◽  
...  
Keyword(s):  
Grain Size ◽  
Phase Composition ◽  
Combustion Synthesis ◽  
Calcination Temperature ◽  
Solution Combustion Synthesis ◽  
X Ray Diffraction ◽  
Spinel Limn2o4 ◽  
Solution Combustion ◽  
Phase Purity ◽  
Diffraction Patterns

Spinel LiMn2O4 was prepared by solution combustion synthesis. The effect of fuel content and calcination procedure on phase composition and microscopic structure of LiMn2O4 was studied. X-ray diffraction patterns showed that fuel content had no obvious influence on the grain size and phase purity of LiMn2O4. Higher calcination temperature led to higher phase purity, lager grain size, and better crystallization of resultant LiMn2O4. Below 600°C the effect of calcination time was inconspicuous, which became notable above 700°C. Scanning electron microscope images showed that nanocrystalline LiMn2O4 was obtained when the calcination temperature was lower than 600°C and the grain size increased at higher temperatures.

scholarly journals The Influence of Surface Preparation, Chewing Simulation, and Thermal Cycling on the Phase Composition of Dental Zirconia

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2133
Author(s):  
Markus Wertz ◽  
Florian Fuchs ◽  
Hieronymus Hoelzig ◽  
Julia Maria Wertz ◽  
Gert Kloess ◽  
...  
Keyword(s):  
Phase Composition ◽  
Rietveld Method ◽  
Tetragonal Zirconia ◽  
Surface Preparation ◽  
Dental Restoration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chewing Simulation ◽  
Yttria Content ◽  
Dental Restorative

The effect of dental technical tools on the phase composition and roughness of 3/4/5 yttria-stabilized tetragonal zirconia polycrystalline (3y-/4y-/5y-TZP) for application in prosthetic dentistry was investigated. Additionally, the X-ray diffraction methods of Garvie-Nicholson and Rietveld were compared in a dental restoration context. Seven plates from two manufacturers, each fabricated from commercially available zirconia (3/4/5 mol%) for application as dental restorative material, were stressed by different dental technical tools used for grinding and polishing, as well as by chewing simulation and thermocycling. All specimens were examined via laser microscopy (surface roughness) and X-ray diffraction (DIN EN ISO 13356 and the Rietveld method). As a result, the monoclinic phase fraction was halved by grinding for the 3y-TZP and transformed entirely into one of the tetragonal phases by polishing/chewing for all specimens. The tetragonal phase t is preferred for an yttria content of 3 mol% and phase t″ for 5 mol%. Mechanical stress, such as polishing or grinding, does not trigger low-temperature degradation (LTD), but it fosters a phase transformation from monoclinic to tetragonal under certain conditions. This may increase the translucency and deteriorate the mechanical properties to some extent.

Applications of X-ray Diffraction Crystallite Size/Strain Analysis to Seismosaurus Dinosaur Bone

1990 ◽  
Vol 34 ◽  
pp. 473-482 ◽  
Author(s):  
Steve J. Chipera ◽  
David L. Bish
Keyword(s):  
New Mexico ◽  
Crystallite Size ◽  
Profile Analysis ◽  
Rietveld Method ◽  
Strain Analysis ◽  
Morrison Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Minor ◽  
20 Nm

AbstractRecently, the remains of a giant Cretaceous Sauropod (~150 My old) were discovered in the Morrison Formation west of Albuquerque, New Mexico. This dinosaur, tentatively named Seismosaurus, was found in an exceptional state of preservation. Although it has been known since the 180Q's that fossilized bone is often composed of the mineral apatite, very few studies have been conducted to characterize farther the fossilized material. In an effort to gain insight into the state of preservation and Hie processes occurring in the bone since deposition, apatite in bone from Seismosaurus was compared with that from a contemporary elk from the Jemez Mountains, New Mexico, and with well-crystallized mineral apatite using X-ray powder diffraction and profile analysis techniques. Crystallite size/strain analyses were conducted using the Scherrer equation, the Warren-Averbaca and single-line methods, and the Rietveld method using the program GSAS. Heating the contemporary elk bone produced a decrease in the full-width-at-half-maximum (FWHM) of the reflections in the diffraction pattern. This decrease in FWHM is due to a decrease in microstrain along with a minor increase in crystallite size. Results from crystallite size/strain analysis show that both Seismosaurus and contemporary elk bone crystallites are elongate parallel to the c-axis. However, Seismosaurus bone crystallites are larger (-20-65 nm) with less strain than the contemporary elk bone crystallites (-8-20 nm), suggesting that if elk bone is an appropriate analog, then Seismosaurus bone must have undergone recrystallization.

scholarly journals Synthesis of bimodally porous titania powders by hydrolysis of titanium tetraisopropoxide

2000 ◽  
Vol 15 (11) ◽  
pp. 2322-2329 ◽  
Author(s):  
Ki Chang Song ◽  
Sotiris E. Pratsinis
Keyword(s):  
Phase Composition ◽  
Calcination Temperature ◽  
Water Concentration ◽  
Nitrogen Adsorption ◽  
Molar Ratio ◽  
Titanium Tetraisopropoxide ◽  
X Ray Diffraction ◽  
Porous Titania ◽  
Nitrogen Adsorption Isotherms ◽  
Hydrolysis Of

Bimodally porous titania powders with controlled phase composition and porosity were made by hydrolysis of titanium tetraisopropoxide (TTIP) and calcination. The extent of calcination was followed by thermogravimetric differential thermal analysis and Fourier transform infrared spectroscopy. The specific surface area (SSA) of the powders ranged from 10 to 500 m2/g as determined by nitrogen adsorption. The SSA increased by decreasing either the water concentration during hydrolysis or the calcination temperature. The pore size distribution was bimodal with fine intraparticle pore diameters at 1–6 nm and larger interparticle pore diameters at 30–120 nm as determined by nitrogen adsorption isotherms. The particle phase composition as determined by x-ray diffraction ranged from amorphous to crystalline anatase and rutile largely proportional to the calcination temperature and to a lesser extent on the initial H2O/TTIP molar ratio.

scholarly journals Micro/nano-hierarchical structured TiO 2 coating on titanium by micro-arc oxidation enhances osteoblast adhesion and differentiation

2019 ◽  
Vol 6 (4) ◽  
pp. 182031 ◽  
Author(s):  
Xumeng Pan ◽  
Yada Li ◽  
Adil O. Abdullah ◽  
Weiqiang Wang ◽  
Min Qi ◽  
...  
Keyword(s):  
Dental Implants ◽  
Xrd Analysis ◽  
Cell Counting ◽  
Minor Amount ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mg63 Cells ◽  
Micro Arc Oxidation ◽  
Osteoblast Adhesion ◽  
A Minor

Nano-structured and micro/nano-hierarchical structured TiO 2 coatings were produced on polished titanium by the micro-arc oxidation (MAO) technique. This study was conducted to screen a suitable structured TiO 2 coating for osteoblast adhesion and differentiation in dental implants. The formulation was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and wettability testing. Adhesion, proliferation and osteogenic differentiation of MG63 cells were analysed by SEM, Cell Counting Kit-8 (CCK-8) and quantitative real-time PCR. The micro/nano-hierarchical structured TiO 2 coating with both slots and pores showed the best morphology and wettability. XRD analysis revealed that rutile predominated along with a minor amount of anatase in both TiO 2 coatings. Adhesion and extension of MG63 cells on the micro/nano-hierarchical structured TiO 2 coating were the most favourable. MG63 cells showed higher growth rates on the micro/nano-hierarchical structured TiO 2 coating at 1 and 3 days. Osteogenic-related gene expression was markedly increased in the micro/nano-hierarchical structured TiO 2 coating group compared with the polished titanium group at 7, 14 and 21 days. These results revealed the micro/nano-hierarchical structured TiO 2 coating as a promising surface modification and suitable biomaterial for use with dental implants.

scholarly journals High Temperature Adsorption of SO2 on Mixed Oxides Derived from CaAl Hydrotalcite-Like Compounds

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 325
Author(s):  
Hailin Wang ◽  
Run Hao ◽  
Meiping Gao ◽  
Zhongshen Zhang ◽  
Zhengping Hao
Keyword(s):  
High Temperature ◽  
Air Pollutants ◽  
High Efficiency ◽  
Mixed Oxides ◽  
Low Cost ◽  
Minor Amount ◽  
So2 Adsorption ◽  
Temperature Programmed ◽  
Calcination Method ◽  
A Minor

SO2 which is usually emitted at high temperature is one of the most important air pollutants. It is of great significance to develop high temperature SO2 adsorbent with high efficiency and low cost. In this work, a series of hydrotalcite-like compound-derived CaAlO and CaXAlO(X = Ce, Co) were prepared by coprecipitation and calcination method, and were employed as adsorbents for SO2 adsorption at high temperature (700 °C). The structure and surface properties of these adsorbents were characterized by XRD, Brunauer–Emmett–Teller (BET), Derivative thermogravimetric analysis (DTG) and CO2-TPD (temperature programmed desorption) measurement. Addition of a minor amount of Ce, Co (5 wt%) could significantly increase the number of weak alkalinity sites. CaO in CaCeAlO showed the best SO2 adsorption capacity of 1.34 g/g, which is two times higher than that of CaO in CaAlO (0.58 g/g).

Sign in / Sign up

Export Citation Format

Share Document