scholarly journals Efficiency of using heteropoly compounds of the type (NH4)2[Co(H2O)4]2[Mo8O27]∙6H2O as catalysts for the production of ethylene

2019 ◽  
Vol 60 (11) ◽  
pp. 85-92
Author(s):  
Nikita A. Panurin ◽  
◽  
Natalya Yu. Isaeva ◽  
Ekaterina B. Markova ◽  
Tatiana F. Sheshko ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Fluorescence Analysis ◽  
Heteropoly Compound ◽  
Cascade Reactions ◽  
Environmental Benefits ◽  
Heteropoly Compounds ◽  
X Ray ◽  
Cell Parameters

Carrying out heterogeneous acid catalysis with the use of heteropoly compounds has received considerable attention due to the great economic and environmental benefits. In spite of this, its industrial application is limited as there are difficulties in catalyst regeneration (settling) caused by its relatively low thermal stability. The aim of present work was to search and select catalysts related to the class of heteropoly compounds for propane cracking, to test the selectivity of the prosses as well as to discuss possible approaches for solving the problem of catalyst deactivation, that can contribute to achieve stable characteristics of solid heteropoly catalysts. Among these approaches are: the development of new catalysts with high thermal stability, the modification of catalysts to promote coke combustion, the inhibition of coke formation on heteropoly compound catalysts during the process, carrying out the reactions in supercritical media and also the cascade reactions using a multifunctional heteropoly catalyst. The obtained catalyst was also studied by physicochemical methods to get deep knowledge about which features of these compounds influence on the catalytic activity. A highly active and selective catalyst for ammonium octomolybdenocobaltate(II) ammonium (NH4)2[Co(H2O)4]2[Mo8O27]∙6H2O was synthesized for cracking associated petroleum gases. The qualitative, quantitative, and structural composition as well as the specific surface area of the obtained catalyst was established by the methods of X-ray diffraction, X-ray phase and fluorescence analysis. It was revealed that ammonium octomolybdenocobaltate(II) crystallizes in a triclinic syngony with cell parameters: а = 8.6292(9) Å b = 9.4795(10) Å c = 12.2071(13) Å α = 104.326(2)° β = 109.910(2)° γ = 100.820(2)°.

Synthesis and structure of the ternary nitride Li6WN4

2005 ◽  
Vol 20 (1) ◽  
pp. 18-21 ◽  
Author(s):  
W. X. Yuan ◽  
J. W. Hu ◽  
Y. T. Song ◽  
W. J. Wang ◽  
Y. P. Xu
Keyword(s):  
Crystal Structure ◽  
Thermal Stability ◽  
Room Temperature ◽  
Powder Diffraction Data ◽  
High Quality ◽  
X Ray ◽  
Cell Parameters ◽  
Tetragonal System ◽  
Ternary Nitride ◽  
Stability Measurements

The ternary nitridotungstate Li6WN4 has been synthesized via the solid state reaction of lithium subnitride, Li3N, with W under nitrogen. High quality X-ray powder diffraction data were collected for the crystal-structure determination. Li6WN4 crystallizes in the tetragonal system, space group P42∕nmc, with cell parameters a=6.6759(3) Å and c=4.9280(3) Å, Z=2. Preliminary thermal stability measurements of Li6WN4 show that it is sensitive to moisture, even at room temperature, and decomposes at high temperatures below 1000 °C under flowing nitrogen.

High-temperature breakdown of the synthetic iodine analogue of vanadinite, Pb5(VO4)3I: an apatite-related compound for iodine radioisotope immobilization?

2012 ◽  
Vol 76 (4) ◽  
pp. 997-1003 ◽  
Author(s):  
S. A. T. Redfern ◽  
S. E. Smith ◽  
E. R. Maddrell
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Complete Loss ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Waste Forms ◽  
Iodine Radioisotope ◽  
Thermal Stability Of

AbstractThe thermal stability of the synthetic iodine analogue of vanadinite, Pb5(VO4)3I, in air has been investigated by in situ high temperature X-ray powder diffraction between 300 and 1070 K. Rietveld refinement of phase fractions shows that breakdown to lead orthovanadate, Pb3(VO4)2, begins at temperatures above 540 K, with complete loss of iodine above 680 K. More than 50 K below the onset of breakdown, the unit-cell parameters of Pb5(VO4)3I show anomalous contraction in the crystallographic x–y plane (reduction of a) which we associate with movement of iodine within the [0001] channels of the structure. The implications of these results for immobilization of 129I in potential apatite-related crystalline radioactive waste forms are discussed.

Synthesis, Characterization, Fluorescence and Antibacterial Activity of the Re(VII) Complex [ReO3(phen)(H2PO4)]・H2O

2012 ◽  
Vol 67 (11) ◽  
pp. 1178-1184 ◽  
Author(s):  
Ahlem Maalaoui ◽  
Olfa B. Said ◽  
Samah T. Akriche ◽  
Salem S. Al-Deyab ◽  
Mohamed Rzaigui
Keyword(s):  
Thermal Stability ◽  
Spectroscopic Properties ◽  
Monoclinic Space Group ◽  
Coordination Geometry ◽  
Unit Cell Parameters ◽  
Neutral Complex ◽  
X Ray ◽  
Cell Parameters ◽  
Acid Ligand ◽  
First Time

Single crystals of a Re(VII) complex, the dihydrogenophosphato phenanthroline trioxo-rhenium monohydrate of formula [ReO3(phen)(H2PO4)]⋅H2O (phen=1,10-phenanthroline), were prepared in aqueous solution. X-Ray analysis shows that it crystallizes in the monoclinic space group P21/c with the unit cell parameters: a=8.611(2), b=13.881(2), c=14.502(4) Å , β =120:87(2)°, V =1487.9(6) Å3 and Z = 4. In the neutral complex, the rhenium is in the oxidation state +VII, coordinated by two nitrogen atoms of the bidentate phen, three terminal oxygen atoms and, for the first time, one oxygen atom of the mono-deprotonated phosphoric acid ligand H2PO-4 , forming a squarebased bipyramidal coordination geometry. The thermal stability, IR, UV/Vis and fluorescence spectroscopic properties are given. The complex shows antimicrobial activity against five different microbes.

scholarly journals Study on the Properties of Semi-Synthetic Motor Oil Castrol 10W-40 after Use in a Diesel Engine

2021 ◽  
Vol 15 (3) ◽  
pp. 432-437
Author(s):  
Taras Chervinskyy ◽  
◽  
Oleg Grynyshyn ◽  
Roman Prokop ◽  
Pavlo Shapoval ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Diesel Engine ◽  
Ir Spectroscopy ◽  
Chemical Properties ◽  
Fluorescence Analysis ◽  
Motor Oil ◽  
X Ray ◽  
Physico Chemical ◽  
Before And After ◽  
Synthetic Motor

The changes in operational and physico-chemical properties of original and used semi-synthetic motor oil Castrol 10W-40 before and after its use in a diesel engine have been investigated. Derivatographic studies were carried out to examine a thermal stability; IR spectroscopy was used to confirm the presence of oil aging products. The composition of the inorganic part of the studied semi-synthetic oils was established by X-ray fluorescence analysis.

An x-ray microprobe based upon a close-coupled focal-spot / glass capillary arrangement

1992 ◽  
Vol 50 (2) ◽  
pp. 1758-1759
Author(s):  
D. A. Carpenter ◽  
M. A. Taylor
Keyword(s):  
Imaging Techniques ◽  
Fluorescence Analysis ◽  
High Sensitivity ◽  
Specimen Preparation ◽  
X Rays ◽  
Glass Capillary ◽  
Close Coupling ◽  
X Ray ◽  
Point To Point ◽  
Beam Damage

The development of intense sources of x rays has led to renewed interest in the use of microbeams of x rays in x-ray fluorescence analysis. Sparks pointed out that the use of x rays as a probe offered the advantages of high sensitivity, low detection limits, low beam damage, and large penetration depths with minimal specimen preparation or perturbation. In addition, the option of air operation provided special advantages for examination of hydrated systems or for nondestructive microanalysis of large specimens.The disadvantages of synchrotron sources prompted the development of laboratory-based instrumentation with various schemes to maximize the beam flux while maintaining small point-to-point resolution. Nichols and Ryon developed a microprobe using a rotating anode source and a modified microdiffractometer. Cross and Wherry showed that by close-coupling the x-ray source, specimen, and detector, good intensities could be obtained for beam sizes between 30 and 100μm. More importantly, both groups combined specimen scanning with modern imaging techniques for rapid element mapping.

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

An analytical microscopic study of metals in fluidized catalytic cracking catalyst

1986 ◽  
Vol 44 ◽  
pp. 854-855
Author(s):  
Clifford S. Rainey
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
Catalytic Cracking ◽  
Catalyst Deactivation ◽  
Coke Formation ◽  
Acid Sites ◽  
Y Zeolite ◽  
Fcc Catalyst ◽  
Fluidized Catalytic Cracking ◽  
High Regeneration

The spatial distribution of V and Ni deposited within fluidized catalytic cracking (FCC) catalyst is studied because these metals contribute to catalyst deactivation. Y zeolite in FCC microspheres are high SiO2 aluminosilicates with molecular-sized channels that contain a mixture of lanthanoids. They must withstand high regeneration temperatures and retain acid sites needed for cracking of hydrocarbons, a process essential for efficient gasoline production. Zeolite in combination with V to form vanadates, or less diffusion in the channels due to coke formation, may deactivate catalyst. Other factors such as metal "skins", microsphere sintering, and attrition may also be involved. SEM of FCC fracture surfaces, AEM of Y zeolite, and electron microscopy of this work are developed to better understand and minimize catalyst deactivation.

Structural Study of a new Compound Based on Acid 1,4-Cyclohexanedicarboxylic (1,4-CDC)

2010 ◽  
Vol 6 (1) ◽  
pp. 891-896
Author(s):  
Manel Halouani ◽  
M. Dammak ◽  
N. Audebrand ◽  
L. Ktari
Keyword(s):  
Aqueous Solution ◽  
Water Molecules ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Compound I ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Cyclohexanedicarboxylic Acid

One nickel 1,4-cyclohexanedicarboxylate coordination polymers, Ni2 [(O10C6H4)(COO)2].2H2O  (I), was hydrothermally synthesized from an aqueous solution of Ni (NO3)2.6H2O, (1,4-CDC) (1,4-CDC = 1,4-cyclohexanedicarboxylic acid) and tetramethylammonium nitrate. Compound (I) crystallizes in the monoclinic system with the C2/m space group. The unit cell parameters are a = 20.1160 (16) Å, b = 9.9387 (10) Å, c = 6.3672 (6) Å, β = 97.007 (3) (°), V= 1263.5 (2) (Å3) and Dx= 1.751g/cm3. The refinement converged into R= 0.036 and RW = 0.092. The structure, determined by single crystal X-ray diffraction, consists of two nickel atoms Ni (1) and Ni (2). Lots of ways of which is surrounded by six oxygen atoms, a carboxyl group and two water molecules.

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