scholarly journals Dephosphorization of hot metal using rare earth oxide-containing slags

2020 ◽  
Vol 39 (1) ◽  
pp. 520-526
Author(s):  
Maolin Ye ◽  
Xiaojun Xi ◽  
Shufeng Yang ◽  
Jingshe Li ◽  
Feng Wang
Keyword(s):  
Rare Earth ◽  
Maximum Degree ◽  
Rare Earth Oxide ◽  
Rare Earth Oxides ◽  
Oxide Content ◽  
Hot Metal ◽  
Factors Influencing ◽  
The Rare Earth

AbstractAn innovative rare earth oxide-containing slag for hot metal dephosphorization was proposed, and the factors influencing the efficiency during the dephosphorization of hot metal using rare earth oxide-containing slags were also studied. An increase in the temperature up to 1,550°C is beneficial to the dephosphorization process, and the maximum degree of dephosphorization for slags containing 6 wt% rare earth oxides is 44.49%; further temperature increases would deteriorate the efficiency, and the degree of dephosphorization decreases to 37.38% at 1,600°C. An increase in the basicity of slags up to 3.0, and the rare earth oxide content up to 6 wt%, improves the dephosphorization efficiency; further increase in the basicity and rare earth oxide content, the efficiency has almost no change. It was also found that an increase in the quantity of slags is beneficial to the dephosphorization reaction.

Nano Crystallite ZrO2, La2O3 and CeO2: Synthesis, Characterization and their Properties

2013 ◽  
Vol 209 ◽  
pp. 212-215
Author(s):  
A.K. Patel ◽  
A.R. Umatt ◽  
B.S. Chakrabarty
Keyword(s):  
Rare Earth ◽  
Surface Area ◽  
Gas Adsorption ◽  
Chemical Properties ◽  
Rare Earth Oxide ◽  
Combustion Method ◽  
Rare Earth Oxides ◽  
Precipitation Method ◽  
Reaction Conditions ◽  
The Rare Earth

It is well known that a minor addition of rare earth oxides can provide a beneficial effect towards various catalytic reactions. Use of rare earth oxide in different applications could improve commercial productivity in an affordable way. Among the rare earth oxides, ZrO2, La2O3 and CeO2 are very interesting due to their various characteristics showing a large range of applications in organic reactions. The changes in the molecular properties of materials at the nano scale level greatly enhance their physical properties as well as chemical properties and activity. Due to the extremely small size of the particles, an increased surface area is provided to the reactant enabling more molecules to react at the same time, thereby speeding up the process. In this work, the enhancement in the catalytic activity of these nano structured rare earth oxides has been studied under different reaction conditions. Nano crystalline ZrO2, La2O3 and CeO2 samples were synthesized using precipitation method and optimum reaction conditions have been established; whereas the corresponding bulk samples were synthesized by combustion method. The identification of phase and crystalline size of synthesized oxides have been done by X-ray diffraction, the band gape of these three oxides in both the forms has been analyzed by UV absorbance and surface area has been determined by gas adsorption analysis (BET). Moreover their different properties and the activity of nano crystallite oxides have also been compared with their bulk counterparts. Even the activity of ZrO2 is also compared with the rare earth oxides La2O3 and CeO2.

scholarly journals Catalytic Oxidation of HCHO over the Sodium-Treated Sepiolite-Supported Rare Earth (La, Eu, Dy, and Tm) Oxide Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 328 ◽  
Author(s):  
Ning Dong ◽  
Qing Ye ◽  
Mengyue Chen ◽  
Shuiyuan Cheng ◽  
Tianfang Kang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Rare Earth ◽  
Catalytic Oxidation ◽  
Rare Earth Oxide ◽  
Catalytic Performance ◽  
Rare Earth Oxides ◽  
Hydroxyl Groups ◽  
In Situ Drifts ◽  
The Rare Earth

The sodium-treated sepiolite (NaSep)-supported rare earth oxide (RE/NaSep; RE = La, Eu, Dy, and Tm) samples were prepared using the rotary evaporation method. Physicochemical properties of these materials were characterized by XRD, SEM, BET, FTIR, XPS, H2–TPR, NH3–TPD, and in situ DRIFTS, and their catalytic activities for formaldehyde (HCHO) (2000 ppm) oxidation were evaluated. The results show that loading of the rare earth oxide on NaSep improved its catalytic performance. Among all the samples, Eu/NaSep performed the best, and complete HCHO conversion was achieved at a temperature of 150 °C and a gas hourly space velocity of 240,000 mL/(g h); a good catalytic activity was still maintained after 45 h of stability test. The catalytic oxidation mechanism of HCHO was studied using the in situ DRIFTS technique. As a result, the effective and stable catalytic performance of the Eu/NaSep sample was mainly due to the presence of hydroxyl groups on the sepiolite surface and the doped rare earth oxides, which contributed to its high performance. HCHO oxidation underwent via the steps of HCHO + O2 → HCOO− + OH− → H2O + CO2. It is concluded that the optimal catalytic activity of Eu/NaSep was associated with the highest Oads/Olatt atomic ratio, the largest amount of hydroxyl groups, the highest acidity, and the best reducibility. The present work may provide new insights into the application in the removal of high-concentration HCHO over the rare earth oxides supported on natural low-cost clays.

Effects of Rare-Earth Oxides Doping on Microstructures and Properties of Al2O3/TiAl Composites

2011 ◽  
Vol 675-677 ◽  
pp. 143-146
Author(s):  
Fen Wang ◽  
Xiao Feng Wang ◽  
Jian Feng Zhu ◽  
Liu Yi Xiang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Rare Earth ◽  
Flexural Strength ◽  
Rare Earth Oxide ◽  
Rare Earth Oxides ◽  
Oxide Content ◽  
The Matrix ◽  
Al2o3 Particles ◽  
Positive Effect

Effects of rare-earth oxides addition (0.38~1.52 mol% of Sm2O3, Eu2O3 and Er2O3) on the property and microstructure of the hot-pressed (1300°C, 2h, 35 MPa) Al2O3 (12 wt %)/TiAl insitu composites have been investigated. The results show that the doping of rare-earth oxides has a positive effect on both mechanical properties and densities of Al2O3/TiAl composites. Densities enhanced with increasing of rare-earth oxides. The flexural strength and fracture toughness were higher than other samples when the rare-earth oxide content was 0.38 mol %. The matrix grains and Al2O3 particles were significantly refined, and Al2O3 particles evenly distributed in the matrix.

Epitaxial Growth of High-κ Dielectrics for GaN MOSFETs

2008 ◽  
Vol 1068 ◽  
Author(s):  
Jesse S. Jur ◽  
Ginger D. Wheeler ◽  
Matthew T. Veety ◽  
Daniel J. Lichtenwalner ◽  
Douglas W. Barlage ◽  
...  
Keyword(s):  
Rare Earth ◽  
Epitaxial Growth ◽  
Field Effect ◽  
Field Effect Transistor ◽  
Rare Earth Oxides ◽  
Oxide Semiconductor ◽  
Native Oxide ◽  
Enhancement Mode ◽  
Effect Transistor ◽  
The Rare Earth

ABSTRACTHigh-dielectric constant (high-κ) oxide growth on hexagonal-GaN (on sapphire) is examined for potential use in enhancement-mode metal oxide semiconductor field effect transistor (MOSFET). Enhancement-mode MOSFET devices (ns > 4×1013 cm−2) offer significant performance advantages, such as greater efficiency and scalability, as compared to heterojunction field effect transistor (HFET) devices for use in high power and high frequency GaN-based devices. High leakage current and current collapse at high drive conditions suggests that the use of a high-κ insulating layer is principle for enhancement-mode MOSFET development. In this work, rare earth oxides (Sc, La, etc.) are explored due to their ideal combination of permittivity and high band gap energy. However, a substantial lattice mismatch (9-21%) between the rare earth oxides and the GaN substrate results in mid-gap defect state densities and growth dislocations. The epitaxial growth of the rare earth oxides by molecular beam epitaxy (MBE) on native oxide passivated-GaN is examined in an effort to minimize these growth related defects and other growth-related limitations. Growth of the oxide on GaN is characterized analytically by RHEED, XRD, and XPS. Preliminary MOS electrical analysis of a 50 Å La2O3 on GaN shows superior leakage performance as compared to significantly thicker Si3N4 dielectric.

On `non-stoichiometric phases' in thin films of rare-earth oxides

1978 ◽  
Vol 34 (6) ◽  
pp. 1025-1027 ◽  
Author(s):  
M. Gasgnier ◽  
P. Caro
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Long Range ◽  
Short Range ◽  
Short Range Order ◽  
Rare Earth Oxides ◽  
Range Order ◽  
Acta Cryst ◽  
The Rare Earth

Kaul & Saxena [Acta Cryst. (1977), A33, 992-996] have reported the existence of long-range and short-range order in a non-stoichiometric phase 'LnO x ' (Ln = rare earth). It is shown that the experiments they are describing are indeed the oxidation of the rare-earth hydride LnH2 into the rare-earth cubic C-type sesquioxide. The interpretation they give of their experiments is to be discarded entirely.

Thermal Evolution and Electrical Properties of Rare-Earth Oxide Doped Zirconia

1988 ◽  
Vol 121 ◽  
Author(s):  
B. S. Chiou ◽  
M. Y. Lee ◽  
J. G. Duh
Keyword(s):  
Activation Energy ◽  
Rare Earth ◽  
Ionic Radius ◽  
Thermal Evolution ◽  
Rare Earth Oxide ◽  
Zirconia Ceramics ◽  
Wet Chemical ◽  
Ir Analysis ◽  
Lower Temperature ◽  
The Rare Earth

ABSTRACTSynthesized zirconia ceramics are prepared through the coprecipita-tion process. Application of the wet chemical approach is aimed at the achievement of highly sintered ceramics at lower temperature. The thermal evolution of the synthesized CeO2-ZrO2 powder is investigated with the aid of DTA and TGA measurement. The exothermic peaks on the DTA thermogram are futher identified by the IR analysis. The effect of CeO on the occurrence of the peaks is probed. For other rare-earth oxiae doped ceramics, such as Nd2O3. and Dy2O3. containing zirconia, the bulk and grain boundary resistances are evaluated by the impedance spectroscopy. The dependence of the associated activation energy in the rare-earth oxide doped zirconia is discussed with respect to the variation of the ionic radius of the rare earth constituent.

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