scholarly journals Synthesis of novel WO3/ZrSiO4 catalysts for dehalogenation of halogenated hydrocarbons

10.30544/411 ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 31-37
Author(s):  
Vesna Nikolic ◽  
Željko Kamberović ◽  
Milisav Ranitović ◽  
Milorad Gavrilovski ◽  
Zoran Anđić
Keyword(s):  
Phase Composition ◽  
Water Vapor ◽  
Environmental Impact ◽  
Chemical Synthesis ◽  
Xrd Analysis ◽  
Production Method ◽  
Laboratory Scale ◽  
Halogenated Hydrocarbons ◽  
Synthesis Routes ◽  
Novel Catalyst

This research aimed to develop a novel catalyst based on WO3/ZrSiO4 system for halogenated hydrocarbons processing. The production method of this catalyst involved extrusion and as such was simplified compared to thermo-chemical synthesis routes. It had a reduced number of process stages and a lower environmental impact at the same time. In order to examine the phase composition of the catalyst after sintering at 800 °C, the XRD analysis was carried out. The catalyst was then tested in chlorodifluoromethane dehalogenation process on laboratory scale at temperatures of 300, 400 and 500 °C in the presence of water vapor. Catalyst achieves high dehalogenation efficiencies of 88.6, 95.9, and 99.5 % for each of the process temperatures, respectively. Obtained results are in the range with those achieved by using thermo-chemically prepared dehalogenation catalysts.

Specifics of Microstructure and Phase Composition of High-Speed Steel R6M5

2013 ◽  
Vol 404 ◽  
pp. 20-24 ◽  
Author(s):  
Маzhyn Skakov ◽  
Bauyrzhan Rakhadilov ◽  
Gaukhar Karipbayeva
Keyword(s):  
Phase Composition ◽  
High Speed ◽  
Volume Fraction ◽  
Electron Backscatter Diffraction ◽  
High Speed Steel ◽  
Spherical Shape ◽  
Xrd Analysis ◽  
Steel R6m5 ◽  
Solid Carbide ◽  
Backscatter Diffraction

In this paper microstructure, morphology, elemental composition, phase composition and crystal structure of the sample steel R6M5 were investigate by using the methods of scanning electron microscopy, electron backscatter diffraction (EBSD) analysis and X-ray diffraction (XRD) analysis. Determined that the microstructure of steel R6M5 after hardening and three-time tempering consists of tempered martensite and solid carbide M6C and MC-type with spherical shape and a diameter of less than 3 μm. Detected that the volume fraction of each carbide amounted to 10.4±0.6% and 2.3±0.4% - for grey and bright carbides, respectively, and that the sizes of bright carbides particles in the microstructure of steel R6M5 are 0.4-4,5 μm, and the sizes of grey carbides particles are 0.5-1.1 μm. XRD analysis showed that the main carbides in the studied steel are carbides М6С and MC, which have complicated the FCC crystal lattice and the Fd3m spatial group. Determined that carbides are uniform and monocrystalline. ESBD analysis with the support of the XRD analysis showed that carbides spherical shape М6С fit to Fe3W3C composition.

scholarly journals 3D Printing in Heterogeneous Catalysis—The State of the Art

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4534 ◽  
Author(s):  
Elżbieta Bogdan ◽  
Piotr Michorczyk
Keyword(s):  
Additive Manufacturing ◽  
Heterogeneous Catalysis ◽  
3D Printing ◽  
Chemical Synthesis ◽  
State Of The Art ◽  
Three Dimensional ◽  
Production Method ◽  
The State ◽  
Monolithic Catalysts ◽  
Selection Of

This paper describes the process of additive manufacturing and a selection of three-dimensional (3D) printing methods which have applications in chemical synthesis, specifically for the production of monolithic catalysts. A review was conducted on reference literature for 3D printing applications in the field of catalysis. It was proven that 3D printing is a promising production method for catalysts.

Comparative study of samarium-doped ceria nanopowders synthesized by various chemical synthesis routes

2020 ◽  
Vol 46 (15) ◽  
pp. 24385-24394 ◽  
Author(s):  
Fariza Kalyk ◽  
Algita Stankevičiūtė ◽  
Gintarė Budrytė ◽  
Giedrė Gaidamavičienė ◽  
Artūras Žalga ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Comparative Study ◽  
Doped Ceria ◽  
Synthesis Routes

A Comparative Study of Granular Agglomeration between 3D Printed Hydroxyapatite and Commercial Bone Graft Granules

2019 ◽  
Vol 798 ◽  
pp. 83-87
Author(s):  
Faungchat Thammarakcharoen ◽  
Ariya Yampakdee ◽  
Bovornwut Buranawat ◽  
Jintamai Suwanprateeb
Keyword(s):  
Phase Composition ◽  
Comparative Study ◽  
Bone Graft ◽  
Water Absorption ◽  
Tricalcium Phosphate ◽  
Water Film ◽  
Xrd Analysis ◽  
High Porosity ◽  
Capillary Action ◽  
3D Printed

Granule characteristics and the agglomeration ability of 3D printed hydroxyapatite granules (3DP HA) when contacting water were compared to those of commercial bone graft granules based on hydroxyapatite/β-tricalcium phosphate/collagen mixture (Sunmax). Microstructure, phase composition, water absorption and granular agglomeration of the granules were characterized. SEM showed that the granule sizes of Sunmax were in the range of 0.8-1.5 mm whereas that of 3DP HA was relatively more uniform at about 1 mm. 3DP HA granules comprised the weaving of numerous minute crystals containing large pores and having high porosity while Sunmax granules were crushed granules and having low porosity. XRD analysis confirmed that Sunmax granules were biphasic hydroxyapatite and β-tricalcium phosphate while 3DP HA granules were monophasic hydroxyapatite. Sunmax granules exhibited greater agglomeration volume than that of 3DP HA granules. However, the water absorption of 3DP HA granules was greater than that of Sunmax granules. The greater agglomeration ability of Sunmax granules was likely due to the collagen constituent of the granules which could act as adhesive to bind granules together in addition to water capillary action. In contrast, 3DP HA granules formed the agglomeration by the water film due to the capillary action only so the efficiency was lower although the water absorption was greater.

Integrated glycerol- and ethanol-based chemical synthesis routes using Cu–Mg–Al LDH-derived catalysts without external hydrogen: Intervention of bio-ethanol co-fed with glycerol

2020 ◽  
Vol 156 ◽  
pp. 975-985 ◽  
Author(s):  
Jirayu Kuljiraseth ◽  
Thanakorn Kumpradit ◽  
Tuangrat Leungcharoenwattana ◽  
Yingyot Poo-arporn ◽  
Sirirat Jitkarnka
Keyword(s):  
Chemical Synthesis ◽  
Synthesis Routes

scholarly journals The Effect of Simultaneous Si and Ti/Mo Alloying on High-Temperature Strength of Fe3Al-Based Iron Aluminides

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4268
Author(s):  
Věra Vodičková ◽  
Martin Švec ◽  
Pavel Hanus ◽  
Pavel Novák ◽  
Antonín Záděra ◽  
...  
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Yield Stress ◽  
Electron Backscatter Diffraction ◽  
Xrd Analysis ◽  
Iron Aluminides ◽  
High Temperature Strength ◽  
X Ray Diffraction ◽  
Backscatter Diffraction

The effect of phase composition and morphology on high-temperature strength in the compression of Fe-Al-Si-based iron aluminides manufactured by casting was investigated. The structure and high-temperature strength in the compression of three alloys—Fe28Al5Si, Fe28Al5Si2Mo, and Fe28Al5Si2Ti—were studied. Long-term (at 800 °C for 100 h) annealing was performed for the achievement of structural stability. The phase composition and grain size of alloys were primarily described by means of scanning electron microscopy equipped with energy dispersive analysis and Electron Backscatter Diffraction (EBSD). The phase composition was verified by X-ray diffraction (XRD) analysis. The effect of Mo and Ti addition as well as the effect of long-term annealing on high-temperature yield stress in compression were investigated. Both additives—Mo and Ti—affected the yield stress values positively. Long-term annealing of Fe28Al5Si-X iron aluminide alloyed with Mo and Ti deteriorates yield stress values slightly due to grain coarsening.

Simulations and Measurements of Water Vapor Flow and Ice Dynamics in a Freeze-Dryer Condenser

2011 ◽  
Author(s):  
Arnab Ganguly ◽  
Alina Alexeenko ◽  
Frank DeMarco
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Mass Flux ◽  
Freeze Drying ◽  
Laboratory Scale ◽  
Vapor Flow ◽  
Ice Accretion ◽  
Production Scale ◽  
Ice Dynamics ◽  
Freeze Dryer

Freeze-drying is a low-pressure, low-temperature condensation pumping process widely used in the manufacture of pharmaceuticals for removal of solvents by sublimation. The performance of a freeze-dryer condenser is largely dependent on the vapor and ice dynamics in the low-pressure environment. The main objective of this work is to develop a modeling and computational framework for analysis of vapor flow and ice dynamics in such freeze-dryer condensers. The direct Simulation Monte Carlo (DSMC) technique is applied to model the relevant physical processes that accompany the vapor flow in the condenser chamber. Low-temperature water vapor and nitrogen molecular model is applied in the DSMC solver SMILE to simulate the bulk vapor transport. The developing ice front on the coils of the condenser is tracked based on the steady state mass flux computed at the nodes of the DSMC surface mesh. Verification of ice accretion simulations has been done by comparison with the solution for analytical free-molecular flow over a circular cylinder. The developed model has also been validated with measurements of ice growth in a laboratory and production scale freeze-dryer using time-lapse imaging. To illustrate the application of the ice accretion algorithm in the area of bio-pharmaceutical freeze-drying, the current work discusses the effect of the condenser geometry and non-condensable gas on non-uniformity of mass flux in a laboratory scale and production scale freeze-dryer condenser. In addition, the simulations are used to predict the ice formation on the coils of the condenser. It was found that in the laboratory scale dryer, the presence of a duct connecting the product chamber and condenser increased non-uniformity by 65% at a sublimation rate of 5 g/hr. The measured ice thickness on the coils of the condenser was found to increase non-linearly. This non-linearity was captured within an accuracy of 1% compared to the measurements towards the end of a 24 hour cycle using an unsteady icing model while that using a steady model was within 14%. In the production dryer, while the steady model predicted the iced coil diameter within an accuracy of 2–5% with respect to the measurements, the unsteady model captured this within an accuracy of 1–6%. The DSMC simulations demonstrate that by augmenting its capabilities with the icing model, it is possible to predict the performance of a freeze-dryer condenser with any arbitrary design.

The character of the structure formation of model alloys of the Fe-Cr-(Zr, Zr-B) system synthesized by powder metallurgy

2020 ◽  
Vol 2 (100) ◽  
pp. 49-57
Author(s):  
Z.A. Duriagina ◽  
M.R. Romanyshyn ◽  
V.V. Kulyk ◽  
T.M. Kovbasiuk ◽  
A.M. Trostianchyn ◽  
...  
Keyword(s):  
Phase Composition ◽  
Powder Metallurgy ◽  
Chemical Composition ◽  
Structure Formation ◽  
Xrd Analysis ◽  
Model Alloy ◽  
Phase Identification ◽  
Laves Phases ◽  
Cr System ◽  
Sintered Alloys

Purpose: The purpose of the work is to synthesize and investigate the character of structure formation, phase composition and properties of model alloys Fe75Cr25, Fe70Cr25Zr5, and Fe69Cr25Zr5B1. Design/methodology/approach: Model alloys are created using traditional powder metallurgy approaches. The sintering process was carried out in an electric arc furnace with a tungsten cathode in a purified argon atmosphere under a pressure of 6·104 Pa on a water cooled copper anode. Annealing of sintered alloys was carried out at a temperature of 800°C for 3 h in an electrocorundum tube. The XRD analysis was performed on diffractometers DRON-3.0M and DRON-4.0M. Microstructure study and phase identification were performed on a REMMA-102-02 scanning electron microscope. The microhardness was measured on a PMT-3M microhardness meter. Findings: When alloying a model alloy of the Fe-Cr system with zirconium in an amount of up to 5%, it is possible to obtain a microstructure of a composite type consisting of a mechanical mixture of a basic Fe2(Cr) solid solution, solid solutions based on Laves phases and dispersive precipitates of these phases of Fe2Zr and FeCrZr compositions. In alloys of such systems or in coatings formed based on such systems, an increase in hardness and wear resistance and creep resistance at a temperature about 800°C will be reached. Research limitations/implications: The obtained results were verified during laser doping with powder mixtures of appropriate composition on stainless steels of ferrite and ferrite-martensitic classes. Practical implications: The character of the structure formation of model alloys and the determined phase transformations in the Fe-Cr, Fe-Cr-Zr, and Fe-Cr-B-Zr systems can be used to improve the chemical composition of alloying plasters during the formation of ferrite and ferrite-martensitic stainless steel coatings. Originality/value: The model alloys were synthesized and their phase composition and microstructure were studied; also, their microhardness was measured. The influence of the chemical composition of the studied materials on the character of structure formation and their properties was analysed.

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