High-Energy Mechanical Synthesis of Nanophase Fluorite-Structured Mixed Oxide Catalysts with a High Redox Activity

1996 ◽  
Vol 454 ◽  
Author(s):  
Alessandra Primavera ◽  
Alessandro Trovarelli ◽  
Jordillorca ◽  
Daniela Terribile ◽  
Carla de Leitenburg ◽  
...  
Keyword(s):  
Lattice Structure ◽  
High Energy ◽  
Temperature Treatment ◽  
Redox Properties ◽  
Redox Activity ◽  
High Temperature Treatment ◽  
Redox Behavior ◽  
High Concentration ◽  
Mixed Oxide Catalysts ◽  
Reduction Techniques

ABSTRACTA series of nanostructured, highly defective, ternary solid solutions containing CeO2, ZrO2, and MnO2 or CuO were prepared by high-energy mechanical milling of individual components. Morphological and redox properties were studied by XRD, HRTEM and temperature-programmed reduction techniques. It was shown that the introduction of small amounts of copper and manganese strongly promotes the redox behavior of cerium at lower temperatures in comparison with CeO2 and CeO2-ZrO2. High temperature treatment of up to 1400K was also shown to further promote overall redox capacity without affecting low-temperature redox behavior. Moreover, evidence is provided to show that Cu and Mn are dissolved within the CeO2 lattice structure. Addition of dopants enhances catalytic redox properties in the oxidation of CO at low temperatures, which is associated with the high concentration of oxygen vacancies that form on the introduction of aliovalent elements into the ceria-zirconia lattice.

RADON Operational Experience in High-Temperature Treatment of Radioactive Wastes

2014 ◽  
Vol 94 ◽  
pp. 121-130 ◽  
Author(s):  
Sergey V. Stefanovsky ◽  
Yuri V. Myshkin ◽  
Dmitri V. Adamovich ◽  
Michael D. Beliy
Keyword(s):  
High Temperature ◽  
Environmental Remediation ◽  
Shaft Furnace ◽  
High Energy ◽  
Temperature Treatment ◽  
Radioactive Wastes ◽  
High Temperature Treatment ◽  
Operational Experience ◽  
Cold Crucible ◽  
Exchange Resins

FSUE Radon deals with collection, transportation, treatment, conditioning, and interim storage and final disposal of conditioned low-and intermediate-level radioactive wastes (LILW) as well as radiation monitoring, decontamination and environmental remediation of Moscow and Moscow area. Liquid LILW with high salinity is subject to vitrification at the Radon full scale vitrification plant using a cold crucible inductive melting (CCIM) at temperatures of 1150-1200 °C. The bench-scale cold crucible based unit is used for research works and feasibility study on new promising ceramic and glass-ceramic waste forms based on incinerator slag and ash. Solid and liquid organic LILWs are treated in a plasma shaft furnace with liquid slagging at temperatures of 1400-1500 °C. Molten slag is solidified in containers yielding a glass-crystalline material with high chemical durability and strong mechanical integrity suitable for safe long-term storage and disposal in both interim repositories and underground sites. One of the promising methods for LILW treatment is application of thermochemical reactions – self-propagating high-temperature synthesis (SHS) with high energy release which is considered as a potential technology for treatment of spent ion-exchange resins, silts and grounds and some specific wastes.

The Nature and Activity of Carbon Black Surfaces

1950 ◽  
Vol 23 (3) ◽  
pp. 625-634 ◽  
Author(s):  
W. R. Smith ◽  
W. D. Schaeffer
Keyword(s):  
Carbon Black ◽  
Surface Activity ◽  
Chemical Properties ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
High Concentration ◽  
Equal Concentration ◽  
Heats Of Adsorption ◽  
Carbon Blacks ◽  
Chemisorbed Oxygen

Abstract While the electron microscope and adsorption isotherm techniques for evaluating the particle size and surface area of carbon blacks have been particularly valuable in interpreting their behavior in rubber, they also emphasize the fact that reinforcement cannot be interpreted solely on this basis. The activity or nature of the surface must also be considered. Heats of adsorption offer a means of evaluating surface activity. The differential heats of adsorption have been measured by precision calorimetry for nitrogen and a series of C4 hydrocarbons on a group of carbon blacks of varying reinforcing ability. Initial sites of high activity were detected. Surface activity decreases with increasing surface coverage. The magnitude of the initial heats parallels the reinforcing properties of the blacks studied. The surface activity and reinforcing ability of an MPC black was found to be greatly reduced by high temperature treatment. These effects were not influenced by the chemical nature of the surface, i.e., the presence of chemisorbed oxygen or volatile substances. In a further phase of this study, the nature of the surface oxide complexes present on carbon blacks has been studied by means of their emission band spectra in a special vacuum discharge tube. Aldehyde and carboxyl radicals were observed in high concentration. Hydroxyl radicals were also present in nearly equal concentration. These data offer a satisfactory interpretation of the pH properties of carbon black and also should prove of value in interpreting other chemical properties.

scholarly journals Study on influencing factors of photocatalytic performance of CdS/TiO2 nanocomposite concrete

2020 ◽  
Vol 9 (1) ◽  
pp. 1160-1169
Author(s):  
Kang He ◽  
Yu Chen ◽  
Mengjun Mei
Keyword(s):  
High Temperature ◽  
Visible Light ◽  
Photocatalytic Performance ◽  
Catalytic Efficiency ◽  
High Energy ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Light Sources ◽  
Photocatalytic Efficiency ◽  
Photocatalytic Concrete

AbstractIn this study, a high-energy ball mill was used to composite nano-TiO2 and CdS, and three kinds of nanocomposite photocatalysts TiO2, CdS/TiO2-R400, and CdS/TiO2-R600 were prepared, which can respond to visible light. The photocatalytic concrete test block was prepared by mixing the nanocomposite photocatalyst and other masses with cement by incorporation method. To study the effect of the photocatalyst content on the photocatalytic performance of nanoconcrete, a total of four catalyst contents (0, 2%, 5%, and 8%) were set. The effects of high-temperature treatment (400°C) and different light sources (ultraviolet and visible light) on photocatalytic efficiency were also considered. The results show that the catalytic efficiency of CdS/TiO2-R400 under two light sources is higher than that of the other two photocatalysts. Compared to ultraviolet light sources, the photocatalytic efficiency of CdS/TiO2 nanocomposite concrete under visible light is lower, and the efficiency is below 9%. The optimal amounts of CdS/TiO2 nanocomposite photocatalyst under ultraviolet and visible light are 2% and 5%, respectively. The high-temperature treatment can improve the photocatalytic performance of CdS/TiO2 nanocomposite photocatalyst by 2% to 3%.

Effect of pH on the formation of deposit from milk on heated surfaces during ultra high temperature processing

1986 ◽  
Vol 53 (1) ◽  
pp. 75-87 ◽  
Author(s):  
Paul J. Skudder ◽  
Brian E. Brooker ◽  
Andrew D. Bonsey ◽  
Norman R. Alvarez-Guerrero
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Skim Milk ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
High Concentration ◽  
Deposit Formation ◽  
Effect Of Ph ◽  
Whole Milk ◽  
Ultra High Temperature

SUMMARYInvestigation of the effect of pH on the formation of deposit from milk during ultra high temperature treatment using a plate-type plant showed that deposit formation was greatly increased when the pH of whole milk was reduced to 6·54, irrespective of whether the adjustment was made through the addition of HCl or lactic acid. Most of the increase in deposition took place in the higher temperature sections of the plant. Conversely, an increase in milk pH to 6·8 using NaOH resulted in considerably less deposit being formed during heat treatment. Reducing the pH of whole milk increased the deposition of both protein and fat, but reduced the deposition of minerals. Despite very high concentration of fat in the deposits, it is unlikely that fatper sewas responsible for increased deposit formation. Deposition also increased when the pH of skim milk was reduced to 6·51 before processing. Electron micrographs of the milks after heat treatment indicated that pH reductions caused the formation of large aggregates containing casein micelles during heating. Fat globules were also present in aggregates formed in whole milk with reduced pH. Slight reductions in the pH of milk before processing appear to enable the pH during heat treatment to fall below a critical value at which coagulation of milk takes place at the heated surfaces.

Experimental Assessment of the Practical Oxidative Stability of Lithium Thiophosphate Solid Electrolytes

2019 ◽  
Author(s):  
Georg Dewald ◽  
Saneyuki Ohno ◽  
Marvin Kraft ◽  
Raimund Koerver ◽  
Paul Till ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Solid State ◽  
Oxidative Stability ◽  
Photoelectron Spectroscopy ◽  
Solid Electrolytes ◽  
Stability Limit ◽  
Lithium Ion ◽  
High Energy ◽  
Redox Activity ◽  
Solid State Batteries

<p>All-solid-state batteries are often expected to replace conventional lithium-ion batteries in the future. However, the practical electrochemical and cycling stability of the best-conducting solid electrolytes, i.e. lithium thiophosphates, are still critical issues that prevent long-term stable high-energy cells. In this study, we use <i>stepwise</i><i>cyclic voltammetry </i>to obtain information on the practical oxidative stability limit of Li<sub>10</sub>GeP<sub>2</sub>S<sub>12</sub>, a Li<sub>2</sub>S‑P<sub>2</sub>S<sub>5</sub>glass, as well as the argyrodite Li<sub>6</sub>PS<sub>5</sub>Cl solid electrolytes. We employ indium metal and carbon black as the counter and working electrode, respectively, the latter to increase the interfacial contact area to the electrolyte as compared to the commonly used planar steel electrodes. Using a stepwise increase in the reversal potentials, the onset potential at 25 °C of oxidative decomposition at the electrode-electrolyte interface is identified. X‑ray photoelectron spectroscopy is used to investigate the oxidation of sulfur(-II) in the thiophosphate polyanions to sulfur(0) as the dominant redox process in all electrolytes tested. Our results suggest that after the formation of these decomposition products, significant redox behavior is observed. This explains previously reported redox activity of thiophosphate solid electrolytes, which contributes to the overall cell performance in solid-state batteries. The <i>stepwise cyclic voltammetry</i>approach presented here shows that the practical oxidative stability at 25 °C of thiophosphate solid electrolytes against carbon is kinetically higher than predicted by thermodynamic calculations. The method serves as an efficient guideline for the determination of practical, kinetic stability limits of solid electrolytes. </p>

Experimental Assessment of the Practical Oxidative Stability of Lithium Thiophosphate Solid Electrolytes

2019 ◽  
Author(s):  
Georg Dewald ◽  
Saneyuki Ohno ◽  
Marvin Kraft ◽  
Raimund Koerver ◽  
Paul Till ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Solid State ◽  
Oxidative Stability ◽  
Photoelectron Spectroscopy ◽  
Solid Electrolytes ◽  
Stability Limit ◽  
Lithium Ion ◽  
High Energy ◽  
Redox Activity ◽  
Solid State Batteries

<p>All-solid-state batteries are often expected to replace conventional lithium-ion batteries in the future. However, the practical electrochemical and cycling stability of the best-conducting solid electrolytes, i.e. lithium thiophosphates, are still critical issues that prevent long-term stable high-energy cells. In this study, we use <i>stepwise</i><i>cyclic voltammetry </i>to obtain information on the practical oxidative stability limit of Li<sub>10</sub>GeP<sub>2</sub>S<sub>12</sub>, a Li<sub>2</sub>S‑P<sub>2</sub>S<sub>5</sub>glass, as well as the argyrodite Li<sub>6</sub>PS<sub>5</sub>Cl solid electrolytes. We employ indium metal and carbon black as the counter and working electrode, respectively, the latter to increase the interfacial contact area to the electrolyte as compared to the commonly used planar steel electrodes. Using a stepwise increase in the reversal potentials, the onset potential at 25 °C of oxidative decomposition at the electrode-electrolyte interface is identified. X‑ray photoelectron spectroscopy is used to investigate the oxidation of sulfur(-II) in the thiophosphate polyanions to sulfur(0) as the dominant redox process in all electrolytes tested. Our results suggest that after the formation of these decomposition products, significant redox behavior is observed. This explains previously reported redox activity of thiophosphate solid electrolytes, which contributes to the overall cell performance in solid-state batteries. The <i>stepwise cyclic voltammetry</i>approach presented here shows that the practical oxidative stability at 25 °C of thiophosphate solid electrolytes against carbon is kinetically higher than predicted by thermodynamic calculations. The method serves as an efficient guideline for the determination of practical, kinetic stability limits of solid electrolytes. </p>

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