نتایج جستجو برای: ceo2
تعداد نتایج: 2688 فیلتر نتایج به سال:
We examined oxidative coupling of methane (OCM) over various Ce-W-O catalysts at 423 K in an electric field. Ce2(WO4)3/CeO2 catalyst showed high OCM activity. In a periodic operation test over Ce2(WO4)3/CeO2 catalyst, C2 selectivity exceeded 60% during three redox cycles. However, Ce2(WO4)3/CeO2 catalyst without the electric field showed low activity, even at 1073 K: CH4 Conv., 6.0%; C2 Sel., 2...
Nanocrystalline sensors having the general formula ZnO + x wt% CeO2, where x = 0, 2, 4 and 6 were prepared by chemical precipitation method and sintered at 400, 600 and 800 C for 2h in static air atmosphere. The crystal structure and the morphology of the prepared samples were investigated and characterized by using XRD, IR, SEM and TEM techniques. The investigation revealed that the average cr...
CeO2 and Y2O3-stabilized zirconia (YSZ) are two typical candidates for electrolyte materials in solid oxide fuel cells attributed to their high ion conductivities. However, the conductivities of these materials are closely connected with high temperatures. Therefore, it is important to develop electrolyte materials which can conduct oxygen ions at lower temperatures. Recent experiments have sho...
The aim of this project was to compare cerium oxide and silver particles of different sizes for their potential for uptake by aquatic species, human exposure via ingestion of contaminated food sources and to assess their resultant toxicity. The results demonstrate the potential for uptake of nano and larger particles by fish via the gastrointestinal tract, and by human intestinal epithelial cel...
Integrated CO2 capture and methanation (ICCM) is attracting more attention to promote the reduction of emission. This work developed applied a set combined materials using Ru/CeO2 as catalyst physically mixed Li, Na, K-doped MgO adsorbent for ICCM process. The influences morphologies CeO2 (rod, particle, cube) in are investigated explicitly terms conversion CH4 yield. Compared with cube morphol...
In this work, polypyrrole/CeO2 nanocomposite (NC) was synthesized in the presence of methylorange as a reactive self-degraded soft template. The field emission scanning electron microscopy(FESEM) images indicate that the CeO2 NPs have a nucleus effect and cause a homogenous PPycore–shell type morphology with an encapsulation of the CeO2 core by the PPy shell. The effect ofNC on acrylic waterbor...
Current industrial catalysts for the water-gas shift reaction are commonly mixtures of Fe-Cr and Zn-Al-Cu oxides, used at temperatures between 350-500oC and 180250oC, respectively. These oxide catalysts are pyrophoric and normally require lengthy and complex activation steps before usage. Improved catalysts are being sought, particularly for lower temperature (e.g., at T<150oC, equilibrium lowe...
A single-step, self-contained method for determining the crystallite-size distribution and shape from experimental x-ray line profile data is presented. It is shown that the crystallite-size distribution can be determined without invoking a functional form for the size distribution, determining instead the size distribution with the least assumptions by applying the Bayesian/MaxEnt method. The ...
This communication describes the fabrication of Pt/CeO2 nanotube@SiO2 core-shell catalysts applied to highly efficient water-gas shift reaction, where the initial CO conversion is 30.2% at 250 °C. Pt/CeO2 nanotube@SiO2 core-shell catalysts show outstanding thermal stability, even after accelerated aging under reaction conditions at 450 °C for 6 h, and the morphology is also unchanged after ther...
Synthesis of dimethyl carbonate (DMC) from CO2 and methanol under milder reaction conditions was performed using reduced cerium oxide catalysts and reduced copper-promoted Ce oxide catalysts. Although the conversion of methanol was low (0.005-0.11%) for 2 h of reaction, DMC was synthesized as low as 353 K and at total pressure of as low as 1.3 MPa using reduced Cu-CeO2 catalyst (0.5 wt% of Cu)....
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