scholarly journals Brownmillerites CaFeO2.5 and SrFeO2.5 as Catalyst Support for CO Oxidation

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6413
Author(s):  
Pierre-Alexis Répécaud ◽  
Monica Ceretti ◽  
Mimoun Aouine ◽  
Céline Delwaulle ◽  
Emmanuel Nonnet ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Catalyst Support ◽  
Catalytic Performance ◽  
Oxidation Catalysis ◽  
Synthesis Methods ◽  
Support Material ◽  
Long Term Stability ◽  
The Impact

The support material can play an important role in oxidation catalysis, notably for CO oxidation. Here, we study two materials of the Brownmillerite family, CaFeO2.5 and SrFeO2.5, as one example of a stoichiometric phase (CaFeO2.5, CFO) and one existing in different modifications (SrFeO2.75, SrFeO2.875 and SrFeO3, SFO). The two materials are synthesized using two synthesis methods, one bottom-up approach via a complexation route and one top-down method (electric arc fusion), allowing to study the impact of the specific surface area on the oxygen mobility and catalytic performance. CO oxidation on 18O-exchanged materials shows that oxygen from SFO participates in the reaction as soon as the reaction starts, while for CFO, this onset takes place 185 °C after reaction onset. This indicates that the structure of the support material has an impact on the catalytic performance. We report here on significant differences in the catalytic activity linked to long-term stability of CFO and SFO, which is an important parameter not only for possible applications, but equally to better understand the mechanism of the catalytic activity itself.

scholarly journals On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Catalytic Performance ◽  
Energy Profiles ◽  
High Concentrations ◽  
3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

Separating the impact of oxygen and water on the long-term stability of n-channel perylene diimide thin-film transistors

2015 ◽  
Vol 26 ◽  
pp. 340-344 ◽  
Author(s):  
Ute Zschieschang ◽  
Konstantin Amsharov ◽  
Martin Jansen ◽  
Klaus Kern ◽  
Hagen Klauk ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Perylene Diimide ◽  
Term Stability ◽  
Long Term Stability ◽  
The Impact

Geochemical Behaviour of Uranium in Sedimentary Formations: Insights From a Natural Analogue Study

2009 ◽  
Author(s):  
Ulrich Noseck ◽  
Vaclava Havlova ◽  
Juhani Suksi ◽  
Thomas Brasser ◽  
Radek Cervinka
Keyword(s):  
Current Knowledge ◽  
Natural Analogue ◽  
Near Surface ◽  
Co2 Partial Pressure ◽  
Long Term Stability ◽  
Reducing Conditions ◽  
Phosphate Mineral ◽  
Sedimentary System ◽  
The Impact

Groundwater data from the natural analogue site Ruprechtov have been evaluated with special emphasis on the uranium behaviour in the so-called uranium-rich clay/lignite horizon. In this horizon in-situ Eh-values in the range of −160 to −280 mV seem to be determined by the SO42−/HS− couple. Under these conditions U(IV) is expected to be the preferential redox state in solution. However, on-site measurements in groundwater from the clay/lignite horizon show only a fraction of about 20% occurring in the reduced state U(IV). Thermodynamic calculations reveal that the high CO2 partial pressure in the clay/lignite horizon can stabilise hexavalent uranium, which explains the occurrence of U(VI). The calculations also indicate that the low uranium concentrations in the range between 0.2 and 2.1μg/l are controlled by amorphous UO2 and/or the U(IV) phosphate mineral ningyoite. This confirms the findings from previous work that the uranium (IV) mineral phases are long-term stable under the reducing conditions in the clay/lignite horizon without any signatures for uranium mobilisation. It supports the current knowledge of the geological development of the site and is also another important indication for the long-term stability of the sedimentary system itself, namely of the reducing geochemical conditions in the near-surface (30m to 60 m deep) clay/lignite horizon. Further work with respect to the impact of changes in redox conditions on the uranium speciation is on the way.

scholarly journals Formation of a Pd/MgO Structured Catalyst for the Aqueous Oxidation of Silane to Silanol

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 834 ◽  
Author(s):  
Zhou ◽  
Cao ◽  
Wang ◽  
Li
Keyword(s):  
Catalytic Activity ◽  
Pd Nanoparticles ◽  
Structured Catalysts ◽  
Long Term Stability ◽  
Plasma Electrolyte ◽  
Structured Catalyst ◽  
Aqueous Oxidation ◽  
Plasma Electrolyte Oxidation ◽  
Fabrication Parameters

The catalytic oxidation of silanes to produce silanols using water as an oxidant at mild temperatures is a major challenge in Si-H activation. Highly efficient and easy-to-recycle catalysts based on Pd nanoparticles are in high demand. In this study, Pd nanoparticles embedded in an MgO porous overlayer on an Mg plate as a structured catalyst was prepared by the plasma electrolyte oxidation (PEO) technique. The Pd/MgO catalyst is strongly anchored to the MgO plate, building a structured catalyst. Fabrication parameters such as the temperature of the electrolyte and applied voltage significantly influenced the structure of the obtained Pd/MgO catalyst and in turn its catalytic activity. The catalytic activities of Pd/MgO were evaluated by activation of a Si-H bond for catalyzing the aqueous oxidation of silanes to silanol at mild temperatures. The catalytic activity of Pd nanoparticles is favored by their electro-deficient state due to influence from the MgO substrate. The Pd/MgO catalyst exhibits good performance stability during recycling. This work paves the way for fabricating structured catalysts with long-term stability and enhanced metal–oxide interaction.

scholarly journals Cu-doped CoS2 polyhedrons with high catalytic activity and long-term stability

2020 ◽  
Vol 63 (7) ◽  
pp. 1337-1344
Author(s):  
Jie Yin ◽  
Pin Chen ◽  
Minglong Lu ◽  
Lili Song ◽  
Renyun Zhang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Catalytic Activity ◽  
Term Stability ◽  
Long Term Stability

Carbon Dioxide Reforming of Methane over Ni/Mo/La2O3-SBA-15 Сatalyst

2012 ◽  
Vol 455-456 ◽  
pp. 960-965
Author(s):  
Jian Huang ◽  
T. Huang ◽  
A. Rongzhang ◽  
Wei Huang ◽  
Ren Xiong Ma
Keyword(s):  
Carbon Dioxide ◽  
Strong Interaction ◽  
Carbon Deposition ◽  
Catalytic Performance ◽  
Stability Test ◽  
X Ray Diffraction ◽  
Carbon Dioxide Reforming ◽  
X Ray ◽  
Long Term Stability

Carbon dioxide reforming of methane over Ni/Mo/ La2O3-SBA-15 was studied. The catalyst was characterized by N2 adsorption, X-ray diffraction, H2-TPR,CO2-TPD and TG-GTA analysis. The results indicated that the introduction of an appropriate amount of La2O3 exhibited a higher activity and stability. In the long term stability test, La2O3 impregnated Ni/Mo-SBA-15 gave the highest conversion and stable activity at 800°C for 250 h. The effect of La was suggested to be due to its lower tendency to carbon deposition. Characterization results showed a strong interaction between La and Mo or Ni which facilitated the improvement of catalytic performance.

Penicillin G Acylase-Fatty Lipid Biocomposite Films Show Excellent Catalytic Activity and Long Term Stability/Reusability

2002 ◽  
Vol 18 (3) ◽  
pp. 483-488 ◽  
Author(s):  
S. Phadtare ◽  
P. Parekh ◽  
A. Gole ◽  
M. Patil ◽  
A. Pundle ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Penicillin G Acylase ◽  
Penicillin G ◽  
Term Stability ◽  
Long Term Stability ◽  
Biocomposite Films

Enhancing catalytic activity and stability for CO2 methanation on Ni@MOF-5 via control of active species dispersion

2015 ◽  
Vol 51 (9) ◽  
pp. 1728-1731 ◽  
Author(s):  
Wenlong Zhen ◽  
Bo Li ◽  
Gongxuan Lu ◽  
Jiantai Ma
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
High Stability ◽  
Active Catalyst ◽  
Active Species ◽  
Co2 Methanation ◽  
Long Term Stability ◽  
Uniform State ◽  
Highly Dispersed

A novel high active catalyst Ni@MOF-5 showed unexpected higher activity under the low temperature for CO2 methanation. The characterization results indicated that Ni was in highly dispersed uniform state over MOF-5. This catalyst performed high stability and showed almost no deactivation in long term stability tests up to 100 h.

scholarly journals New insights into phosphate based materials for the immobilisation of actinides

2017 ◽  
Vol 105 (11) ◽  
Author(s):  
Stefan Neumeier ◽  
Yulia Arinicheva ◽  
Yaqi Ji ◽  
Julia M. Heuser ◽  
Piotr M. Kowalski ◽  
...  
Keyword(s):  
Ceramic Materials ◽  
Synthesis Methods ◽  
Atomistic Modeling ◽  
Modeling Tools ◽  
Long Term Stability ◽  
Key Points ◽  
Activation Products ◽  
Experimental Approaches ◽  
Fission And Activation Products

AbstractThis paper focuses on major phosphate-based ceramic materials relevant for the immobilisation of Pu, minor actinides, fission and activation products. Key points addressed include the recent progress regarding synthesis methods, the formation of solid solutions by structural incorporation of actinides or their non-radioactive surrogates and waste form fabrication by advanced sintering techniques. Particular attention is paid to the properties that govern the long-term stability of the waste forms under conditions relevant to geological disposal. The paper highlights the benefits gained from synergies of state-of-the-art experimental approaches and advanced atomistic modeling tools for addressing properties and stability of

Sign in / Sign up

Export Citation Format

Share Document