scholarly journals Enhanced formaldehyde-removal over modified cryptomelane catalysts

2021 ◽  
Vol 947 (1) ◽  
pp. 012024
Author(s):  
Trong-Phu Tran ◽  
Xuan-Phuc Ta-Thi ◽  
Kim-Chau Nguyen ◽  
Duy-Nhan Tran ◽  
Thuy-Duong Nguyen-Phan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Relative Humidity ◽  
Oxidation States ◽  
X Ray Diffraction ◽  
Titration Method ◽  
Element Analysis ◽  
X Ray ◽  
Wide Range ◽  
Formaldehyde Removal ◽  
Diffraction Patterns

Abstract M-OMS-2 materials (M = K+, Cu2+, Co2+) were prepared by an uncomplicated reflux method, and the cryptomelane crystalline structure was confirmed by X-ray diffraction patterns. Element analysis recorded ~56 - ~59 wt.% of Mn in the three synthesized samples and ~2.8 wt.% loadings of dopants over Co-OMS-2 and Cu-OMS-2 materials. A titration method valued the average oxidation states of manganese at 3.60, 3.71 and 3.77 for K-OMS-2, Co-OMS-2 and Cu-OMS-2, respectively. In comparison with K-OMS-2, Co and Cu dopants depicted a significant enhancement catalytic activity in removal of formaldehyde at low (5%) and high (65 %) relative humidity (RH). Cu-OMS-2 showed the highest catalyst performance with ~90 % of formaldehyde conversion at 150 °C, 65% RH, whereas only ~40 % (for Co-OMS-2) and ~26 % (for K-OMS-2) of that were observed. The finding results promised a potential Cu-OMS-2 material for designed low-costly catalyst in formaldehyde removal at a wide range of RH.

2D X-ray diffraction and molecular modelling of the crystalline structure of polyesters under uniaxial stress

2021 ◽  
pp. 096739112199822
Author(s):  
Ahmed I Abou-Kandil ◽  
Gerhard Goldbeck
Keyword(s):  
Crystalline Structure ◽  
Molecular Modelling ◽  
Three Dimensional ◽  
Uniaxial Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Modelling Techniques ◽  
Diffraction Patterns

Studying the crystalline structure of uniaxially and biaxially drawn polyesters is of great importance due to their wide range of applications. In this study, we shed some light on the behaviour of PET and PEN under uniaxial stress using experimental and molecular modelling techniques. Comparing experiment with modelling provides insights into polymer crystallisation with extended chains. Experimental x-ray diffraction patterns are reproduced by means of models of chains sliding along the c-axis leading to some loss of three-dimensional order, i.e. moving away from the condition of perfect register of the fully extended chains in triclinic crystals of both PET and PEN. This will help us understand the mechanism of polymer crystallisation under uniaxial stress and the appearance of mesophases in some cases as discussed herein.

X-ray powder diffraction analysis of the heteropoly-molybdate (MoO2)0.5PMo14O42

2003 ◽  
Vol 18 (3) ◽  
pp. 236-239 ◽  
Author(s):  
L. Marosi ◽  
J. Cifré ◽  
C. Otero Areán
Keyword(s):  
Catalytic Activity ◽  
Diffraction Analysis ◽  
Computer Modeling ◽  
Powder Diffraction ◽  
Rietveld Analysis ◽  
Nitrogen Atmosphere ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

The new heteropoly blue compound (MoO2)0.5PMo14O42, which is relevant in the context of catalytic activity of heteropoly-molybdates, was prepared by controlled thermolysis of (NH4)3PMo12O40 at 730 K in a nitrogen atmosphere. Powder X-ray diffraction analysis showed that this compound has a cubic unit cell, space group Pn3m (No. 224), with ao=11.795(2) Å, Z=2 and DXR=4.2466 g cm−3. Computer modeling and Rietveld analysis of powder diffraction patterns led to a proposed structure of the corresponding Keggin-cage unit PMo14O42.

An X-ray diffraction system with controlled relative humidity and temperature

1996 ◽  
Vol 11 (4) ◽  
pp. 288-289 ◽  
Author(s):  
H. Hashizume ◽  
S. Shimomura ◽  
H. Yamada ◽  
T. Fujita ◽  
H. Nakazawa ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Control Unit ◽  
Saturated Water Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Saturated Water ◽  
Sample Chamber ◽  
Diffraction Patterns ◽  
Xrd Patterns

A system enabling X-ray diffraction patterns under controlled conditions of relative humidity and temperature has been devised and combined with an X-ray powder diffractometer. Relative humidity in the sample space is controlled by mixing dry N2 gas with saturated water vapor. Temperatures of the sample and inner wall of the sample chamber are monitored by two attached thermocouples and the information was fed back to the control unit. Relative humidity between 0% and the 95%, and temperature between room temperature and 60 °C can be controlled. All parameters including those for XRD are programmable and the system runs automatically. The function of the system was checked by recording the XRD patterns of montmorillonite (a clay mineral) and NaCl under increasing and decreasing relative humidity.

scholarly journals Iron-containing phases in metallurgical and coke dusts as well as in bog iron ore

Nukleonika ◽  
2017 ◽  
Vol 62 (2) ◽  
pp. 187-195 ◽  
Author(s):  
Tadeusz Szumiata ◽  
Marzena Rachwał ◽  
Tadeusz Magiera ◽  
Katarzyna Brzózka ◽  
Małgorzata Gzik-Szumiata ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Spinel Structure ◽  
Iron Ore ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Phases ◽  
Coke Plants ◽  
Wide Range ◽  
Specific Magnetic Susceptibility ◽  
Diffraction Patterns

Abstract Several samples of dusts from steel and coke plants (collected mostly with electro filters) were subjected to the investigation of content of mineral phases in their particles. Additionally, sample of bog iron ore and metallurgical slurry was studied. Next, the magnetic susceptibility of all the samples was determined, and investigations of iron-containing phases were performed using transmission Mössbauer spectrometry. The values of mass-specific magnetic susceptibility χ varied in a wide range: from 59 to above 7000 × 10−8 m-3·kg−1. The low values are determined for bog iron ore, metallurgical slurry, and coke dusts. The extremely high χ was obtained for metallurgical dusts. The Mössbauer spectra and X-ray diffraction patterns point to the presence of the following phases containing iron: hematite and oxidized magnetite (in coke and metallurgical dusts as well as metallurgical slurry), traces of magnetite fine grains fraction (in metallurgical dusts), amorphous glassy silicates with paramagnetic Fe3+ and Fe2+ ions, traces of pyrrhotite (in coke dusts), α-Fe and nonstoichiometric wüstite (in metallurgical slurry), as well as ferrihydrite nanoparticles (in bog iron ore). For individual samples of metallurgical dusts, the relative contributions of Fe2+/3+ ions in octahedral B sites and Fe2+ ions in tetrahedral A sites in magnetite spinel structure differs considerably.

scholarly journals Ag/AgCl/MIL-101(Fe) Catalyzed Degradation of Methylene Blue under Visible Light Irradation

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1453 ◽  
Author(s):  
Yun Liu ◽  
Yuanhong Xie ◽  
Mingjin Dai ◽  
Qingjiao Gong ◽  
Zhi Dang
Keyword(s):  
Methylene Blue ◽  
Catalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Box Behnken Design ◽  
X Ray ◽  
Plasmonic Material ◽  
Fenton Catalyst ◽  
Diffraction Patterns

A novel photo-Fenton catalyst named Ag/AgCl/MIL-101(Fe) was synthesized by the method of precipitation and photo reduction and characterized by X-ray diffraction patterns (XRD), Brunauer-Emmett-Teller (BET) measurements, Fourier transform infrared spectra (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra. Moreover, the catalytic activity of the synthesized catalyst was tested using methylene blue (MB) as the target pollutant. The obtained results illustrated that the plasmonic material Ag/AgCl was successfully loaded on MIL-101(Fe) and the obtained catalyst exhibited an excellent catalytic activity under visible light at the neutral pH. According to the analyses of Plackett-Burman and Box-Behnken design, the optimum conditions for MB degradation were obtained. Under these conditions, the MB decolorization and mineralization efficiencies could reach to 99.75% and 65.43%, respectively. The recycling experiments also showed that the as-prepared catalyst displayed good reusability. In addition, the possible reaction mechanisms for the heterogeneous photo-Fenton system catalyzed by Ag/AgCl/MIL-101(Fe) were derived. The synthesized catalyst provides a promising approach to degrade organic pollutants in waste water.

Powder diffraction analysis of an interstratified marcasite/pyrite structure

1995 ◽  
Vol 10 (3) ◽  
pp. 198-203 ◽  
Author(s):  
Neil E. Johnson ◽  
Sidney S. Pollack ◽  
Elizabeth A. Frommell ◽  
Patricia A. Eldredge
Keyword(s):  
Catalytic Activity ◽  
Stacking Faults ◽  
Catalyst Precursor ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Naturally Occurring ◽  
Benzylic Carbon ◽  
Diffraction Peaks ◽  
Diffraction Patterns

A synthetic catalyst precursor formed by sulfiding ferrihydrite (Fe3+O(OH)) in the presence of a hydrogen donor produces X-ray diffraction patterns resembling a mixture of both naturally occurring FeS2 polymorphs marcasite and pyrite. The diffraction peaks display a differential broadening, however, wherein only those peaks coincident to both marcasite and pyrite are strong and sharp, a feature that cannot be accounted for by a simple physical mixture. The broadening is analogous to that found in hexagonal cobalt, where occasional stacking faults produce interstratification of the hexagonal and cubic close-packed forms, resulting in strongly coherent diffraction only along the stacking direction. The crystal structures of marcasite and pyrite are virtually identical if viewed perpendicular to the (101) and (001) planes, respectively. Calculation of diffraction patterns based upon models of interstratifying marcasite and pyrite layers along these planes demonstrates that a sequence with marcasite-to-pyrite and pyrite-to-marcasite stacking fault probabilities of 0.22 provides a good fit to the experimental pattern. This interstratified material is a precursor to a species that shows catalytic activity for cleaving C-C bonds between aromatic rings and benzylic carbon atoms at low (<350 °C) temperatures.

scholarly journals Enhanced hydrogen evolution reaction on hybrids of cobalt phosphide and molybdenum phosphide

2017 ◽  
Vol 4 (3) ◽  
pp. 161016 ◽  
Author(s):  
Si-Ling Fang ◽  
Tsu-Chin Chou ◽  
Satyanarayana Samireddi ◽  
Kuei-Hsien Chen ◽  
Li-Chyong Chen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Electrolysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cobalt Phosphide ◽  
Production Of Hydrogen ◽  
Molybdenum Phosphide ◽  
Diffraction Patterns

Production of hydrogen from water electrolysis has stimulated the search of sustainable electrocatalysts as possible alternatives. Recently, cobalt phosphide (CoP) and molybdenum phosphide (MoP) received great attention owing to their superior catalytic activity and stability towards the hydrogen evolution reaction (HER) which rivals platinum catalysts. In this study, we synthesize and study a series of catalysts based on hybrids of CoP and MoP with different Co/Mo ratio. The HER activity shows a volcano shape and reaches a maximum for Co/Mo = 1. Tafel analysis indicates a change in the dominating step of Volmer–Hyrovský mechanism. Interestingly, X-ray diffraction patterns confirmed a major ternary interstitial hexagonal CoMoP 2 crystal phase is formed which enhances the electrochemical activity.

Further studies of low-angle X-ray diffraction patterns of collagen

1959 ◽  
Vol 252 (1269) ◽  
pp. 197-216 ◽  
Keyword(s):  
Electron Microscopy ◽  
Density Distribution ◽  
Heavy Atom ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heavy Atoms ◽  
Density Distributions ◽  
Wide Range ◽  
Diffraction Patterns

Experiments were carried out on the drying of collagen fibres in vacuo at temperatures up to 200°C. Low-angle X-ray diffraction patterns of material so treated differed markedly from those of collagen dried in vacuo at room temperature, which invalidates the comparison of the latter with density distributions observed by electron microscopy. One-dimensional Patterson functions plotted for a wide range of protein hydration, together with some evidence from electron microscopy, provided helpful pointers to the density distribution in dry collagen, and strong evidence in support of a model for wet collagen consisting of a rectangular density distribution function, such that each period along the fibril has a band of higher density and an interband of lower density. The width of the band was found to be 0·46 of the period by making use of results obtained by ‘staining’ the fibres with heavy atoms. This model of the wet fibres, and the use of difference Patterson functions, made possible the elucidation of the effects of staining with silver nitrate, iodine, phosphotungstic acid, and osmium tetroxide. The major features of the distributions of these stains could be deter­mined with results consistent with the observations of electron microscopy, for those stains detectable by this means. The diffraction method was successful in detecting heavy-atom staining not visible in the electron microscope. Each of the stains considered gave somewhat similar staining patterns, a prominent feature of which was a pair of dense bands 0·8 d ( d being half the collagen period) apart, at the ends of the wet collagen band. Most of the iodine which entered these particular sites was very easily removed, but some of it was more firmly bound in these and other positions.

Texture of Polycrystalline MoSxThin Films Magnetron Sputtered from a Metallic Target in Ar-H2S Atmospheres

2002 ◽  
Vol 721 ◽  
Author(s):  
Volkmar Weiß ◽  
Rainald Mientus ◽  
Klaus Ellmer
Keyword(s):  
Gas Flow ◽  
Film Growth ◽  
Bragg Reflection ◽  
X Ray Diffraction ◽  
Avrami Model ◽  
X Ray ◽  
Si Substrates ◽  
Wide Range ◽  
Diffraction Patterns ◽  
Kinetic Calculations

AbstractThe textured film growth of polycrystalline MoSxfilms on Si substrates deposited by reactive magnetron sputtering with H2S from a molybdenum target has been investigated. Over a wide range of gas flow ratios FH2S/(FH2S+FAr) from 1% to 75% only x-ray diffraction patterns of randomly stacked S-Mo-S layers of the MoS2phase were detected which indicates turbostratic growth of the van-der-Waals layers comparable to the growth of graphite at low temperatures. The extended distance of the c-lattice planes depends on the sputtering conditions and can also be explained by the turbostratic model. Low deposition rates and high substrate temperatures improved the quality of the films towards the requested (001) texture and low c-lattice strain. The results from the in situ-energy dispersive x-ray diffraction (EDXRD) technique using synchrotron radiation allowed kinetic calculations of the time dependent behaviour of the peak area of the (0 0 21) Bragg reflection signals according to the Johnson-Mehl-Avrami model. They revealed that the grain growth is restricted in dimensions if a completed nucleation is assumed.

X-ray diffraction studies of solid solutions of Cr-, Mn-, Fe-, Co-, and Ni-containing transition metal spinel oxides

1995 ◽  
Vol 10 (3) ◽  
pp. 214-220 ◽  
Author(s):  
G. C. Allen ◽  
K. R. Hallam ◽  
J. A. Jutson
Keyword(s):  
Transition Metal ◽  
Metal Oxide ◽  
Solid Solutions ◽  
Cell Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Spinel Oxides ◽  
Steel Surfaces ◽  
Diffraction Patterns

A wide range of transition metal oxide solid solutions have been prepared and characterised using powder X-ray diffraction (MnxCo1−xFe2O4, FexCo1−xFe2O4, NixCo1−xFe2O4, FeFexCr2−xO4, MnFexCr2−xO4, MnxFe1−xCr2O4, MnxFe1−xFe2O4, NixFe1−xFe2O4). Calibration curves have been obtained relating oxide composition to unit cell parameter or d spacing. From these curves it is possible to identify the composition of oxides formed on steel surfaces in varied industrial environments. Even when poor diffraction patterns are obtained and little sample is available, an estimate of composition can be made.

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