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.

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 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.

Lean NOxReduction by Hydrogen over Pt-Supported Rare Earth Oxide Catalysts and Their In Situ DRIFTs Study

2009 ◽  
Vol 82 (9) ◽  
pp. 1197-1202 ◽  
Author(s):  
Masahiro Itoh ◽  
Koji Motoki ◽  
Makoto Saito ◽  
Jun Iwamoto ◽  
Ken-ichi Machida
Keyword(s):  
Rare Earth ◽  
Rare Earth Oxide ◽  
Oxide Catalysts ◽  
In Situ Drifts

scholarly journals Ultra-Small Pd(0) Nanoparticles into a Designed Semisynthetic Lipase: An Efficient and Recyclable Heterogeneous Biohybrid Catalyst for the Heck Reaction under Mild Conditions

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2358 ◽  
Author(s):  
David Lopez-Tejedor ◽  
Blanca de las Rivas ◽  
Jose M. Palomo
Keyword(s):  
Catalytic Activity ◽  
Protein Structure ◽  
Heck Reaction ◽  
Catalytic Performance ◽  
Reducing Agent ◽  
Chemically Modified ◽  
Mild Conditions ◽  
In Situ Formation ◽  
Geobacillus Thermocatenulatus

A novel heterogeneous enzyme-palladium (Pd) (0) nanoparticles (PdNPs) bionanohybrid has been synthesized by an efficient, green, and straightforward methodology. A designed Geobacillus thermocatenulatus lipase (GTL) variant genetically and then chemically modified by the introduction of a tailor-made cysteine-containing complementary peptide- was used as the stabilizing and reducing agent for the in situ formation of ultra-small PdNPs nanoparticles embedded on the protein structure. This bionanohybrid was an excellent catalyst in the synthesis of trans-ethyl cinnamate by Heck reaction at 65 °C. It showed the best catalytic performance in dimethylformamide (DMF) containing 10–25% of water as a solvent but was also able to catalyze the reaction in pure DMF or with a higher amount of water as co-solvent. The recyclability and stability were excellent, maintaining more than 90% of catalytic activity after five cycles of use.

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.

scholarly journals Effects of rare-earth oxides on the microstructure and properties of Fe-based friction materials synthesized by in situ carbothermic reaction from vanadium-bearing titanomagnetite concentrates

RSC Advances ◽  
2019 ◽  
Vol 9 (36) ◽  
pp. 20687-20697
Author(s):  
Dajun Zhai ◽  
Yue Shui ◽  
Keqin Feng ◽  
Yanyan Zhang
Keyword(s):  
Rare Earth ◽  
Tribological Properties ◽  
Rare Earth Oxides ◽  
Frictional Material ◽  
Friction Materials ◽  
Microstructure And Properties ◽  
Iron Based

In this work, we prepared an iron-based frictional material from vanadium-bearing titanomagnetite concentrates by in situ carbothermic reaction with improved tribological properties.

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