Catalytic performance of rare earth oxides in ketonization of acetic acid

2011 ◽  
Vol 346 (1-2) ◽  
pp. 79-86 ◽  
Author(s):  
Yasuhiro Yamada ◽  
Masaki Segawa ◽  
Fumiya Sato ◽  
Takashi Kojima ◽  
Satoshi Sato
Keyword(s):  
Acetic Acid ◽  
Rare Earth ◽  
Catalytic Performance ◽  
Rare Earth Oxides

Synthesis of Dimethyl Carbonate from Carbon Dioxide, Propylene Epoxide and Methanol

2013 ◽  
Vol 734-737 ◽  
pp. 2120-2123
Author(s):  
Tao Fang ◽  
Chong Jing Liao ◽  
Zhen Xiao Duan ◽  
Guo Zhi Fan
Keyword(s):  
Carbon Dioxide ◽  
Rare Earth ◽  
Dimethyl Carbonate ◽  
Catalytic Performance ◽  
Rare Earth Oxides ◽  
Co Catalyst

Dimethyl carbonate (DMC) was synthesized from carbon dioxide, propylene epoxide (PO) and methanol. The catalytic performance of K2CO3, KI, rare earth oxides including CeO2, Y2O3, La2O3 and Yb2O3 was investigated. Acceptable conversion of PO but poor selectivity to DMC was obtained using K2CO3 or KI as the sole catalyst compared to that obtained in the presence of rare earth oxides. Significant improvement in the selectivity to DMC was obtained catalyzed by co-catalyst composed of K2CO3 and Yb2O3, and 42.4% selectivity to DMC, which is higher than that obtained using K2CO3 or Yb2O3 as the sole catalyst under the identical conditions, was obtained. The influence of the amount of PO was also investigated, and the results showed that the conversion of PO is dependent on its amount.

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.

Effect of Rare Earth Oxides on Electrical Properties of Spark Plasma Sintered AlN Ceramics

2015 ◽  
Vol 30 (3) ◽  
pp. 267
Author(s):  
HUANG Lin-Yun ◽  
LI Chen-Hui ◽  
KE Wen-Ming ◽  
SHI Yu-Sheng ◽  
HE Zhi-Yong ◽  
...  
Keyword(s):  
Rare Earth ◽  
Electrical Properties ◽  
Rare Earth Oxides ◽  
Spark Plasma

A glance on rare earth oxides: importance, reserves, demand, applications, critical uncertainties, global economy, and zeta potential characterization

2020 ◽  
Vol 05 ◽  
Author(s):  
Silas Santos ◽  
Orlando Rodrigues ◽  
Letícia Campos
Keyword(s):  
Rare Earth ◽  
Zeta Potential ◽  
Sample Preparation ◽  
Rare Earths ◽  
Smart Materials ◽  
Global Economy ◽  
Materials Science ◽  
Functional Materials ◽  
Rare Earth Oxides ◽  
Interparticle Forces

Background: Innovation mission in materials science requires new approaches to form functional materials, wherein the concept of its formation begins in nano/micro scale. Rare earth oxides with general form (RE2O3; RE from La to Lu, including Sc and Y) exhibit particular proprieties, being used in a vast field of applications with high technological content since agriculture to astronomy. Despite of their applicability, there is a lack of studies on surface chemistry of rare earth oxides. Zeta potential determination provides key parameters to form smart materials by controlling interparticle forces, as well as their evolution during processing. This paper reports a study on zeta potential with emphasis for rare earth oxide nanoparticles. A brief overview on rare earths, as well as zeta potential, including sample preparation, measurement parameters, and the most common mistakes during this evaluation are reported. Methods: A brief overview on rare earths, including zeta potential, and interparticle forces are presented. A practical study on zeta potential of rare earth oxides - RE2O3 (RE as Y, Dy, Tm, Eu, and Ce) in aqueous media is reported. Moreover, sample preparation, measurement parameters, and common mistakes during this evaluation are discussed. Results: Potential zeta values depend on particle characteristics such as size, shape, density, and surface area. Besides, preparation of samples which involves electrolyte concentration and time for homogenization of suspensions are extremely valuable to get suitable results. Conclusion: Zeta potential evaluation provides key parameters to produce smart materials seeing that interparticle forces can be controlled. Even though zeta potential characterization is mature, investigations on rare earth oxides are very scarce. Therefore, this innovative paper is a valuable contribution on this field.

Catalytic performance in methane combustion of rare-earth perovskites RECo0.50Mn0.50O3 (RE: La, Er, Y)

2011 ◽  
Vol 172 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Gina Pecchi ◽  
Claudia Campos ◽  
Octavio Peña
Keyword(s):  
Rare Earth ◽  
Methane Combustion ◽  
Catalytic Performance

Critical Current of Bi-2212 Single Crystal by Doping Oxides as a Pinning Center

2014 ◽  
Vol 95 ◽  
pp. 175-180
Author(s):  
Takuya Agou ◽  
Hiroya Imao
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Single Crystals ◽  
Crystal Surface ◽  
Rare Earth Oxides ◽  
Pinning Centers ◽  
Current Path ◽  
Pinning Center ◽  
Superconducting Current ◽  
A Current

It is necessary to formpinning centers in superconductors to allow the flow of large currents throughthe specimens. To clarify the properties of pinning centers, it is preferableto investigate single crystals. In this study, heat treatment was used to dopevarious oxides into Bi2Sr2CaCu2Ox(Bi-2212) single crystals prepared by self-flux methods and the criticalcurrent (Ic) was measured. The oxides used in this study were Al2O3and the rare earth oxides Er2O3and Nd2O3. At 77K, Nd2O3and Er2O3 are magnetic, whereas Al2O3is nonmagnetic. The Ic of the samples were measured as a current per width of 1cm (Ics). The resulting Ics of the Bi-2212 single crystal was 2.8A/cm and thatof the Al2O3 doped Bi-2212 sample was 4.5A/cm. Comparedwith these samples, doping the other rare earth oxides gave Ics values inexcess 10A/cm. The results indicated that the doping oxides were effective inoperating as pinning centers in the samples. We assumed the current path in asingle crystal, and calculated the Ics by superconducting current simulation.The results indicated that the oxides permeated from a crystal surface in aporous shape. The oxides increase the current which flow in the Cu-O2planes that are parallel to the a-b plane.

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