Electron donating properties and catalytic activity of samarium oxide and its mixed oxides with alumina

1995 ◽  
Vol 55 (2) ◽  
pp. 399-406 ◽  
Author(s):  
S. Sugunan ◽  
J. M. Jalaja
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
Samarium Oxide

Study of nickel-molybdenum catalysts for methanation of carbon monoxide

1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Minor Component ◽  
Fast Neutrons ◽  
Scanning Calorimetry ◽  
Low Concentrations ◽  
Γ Rays ◽  
Molybdenum Catalysts ◽  
Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

Synthesis by sol–gel process, characterization and catalytic activity of vanadia–silica mixed oxides

2005 ◽  
Vol 351 (46-48) ◽  
pp. 3624-3629 ◽  
Author(s):  
Mariza Alves Figueiredo ◽  
André Luiz de Faria ◽  
Marilda das Dores Assis ◽  
Herenilton Paulino Oliveira
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Process Characterization ◽  
Sol Gel Process

Electron Donating, Acid-Base and Catalytic Properties of Perovskite-Type Mixed Oxides of Rare Earths

1995 ◽  
Vol 60 (6) ◽  
pp. 977-982
Author(s):  
S. Sugunan ◽  
V. Meera
Keyword(s):  
Catalytic Activity ◽  
Electron Donor ◽  
Rare Earths ◽  
Electron Affinity ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Surface Acidity ◽  
Electron Acceptors ◽  
Acid Base ◽  
Perovskite Type

The electron donor properties of perovskite-type mixed oxides (LaFeO3, PrFeO3, SmFeO3, LaCoO3, PrCoO3, SmCoO3, LaNiO3, PrNiO3 and SmNiO3) were studied based on the adsorption of electron acceptors exhibiting different electron affinity viz. 7,7,8,8-tetracyanoquinodimethane, 2,3,5,6-tetrachloro-1,4-benzoquinone, p-dinitrobenzene, and m-dinitrobenzene. The surface acidity/basicity of the oxides was determined using a set of Hammett indicators. The data were correlated with the catalytic activity of the oxides for the reduction of cyclohexanone with 2-propanol.

scholarly journals Copper-Containing Mixed Metal Oxides (Al, Fe, Mn) for Application in Three-Way Catalysis

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1344
Author(s):  
Tim Van Everbroeck ◽  
Radu-George Ciocarlan ◽  
Wouter Van Hoey ◽  
Myrjam Mertens ◽  
Pegie Cool
Keyword(s):  
Catalytic Activity ◽  
Spinel Structure ◽  
Mixed Oxides ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Application ◽  
Mixed Spinel ◽  
Co Precipitation ◽  
Three Way Catalysis

Mixed oxides were synthesized by co-precipitation of a Cu source in combination with Al, Fe or Mn corresponding salts as precursors. The materials were calcined at 600 and 1000 °C in order to crystallize the phases and to mimic the reaction conditions of the catalytic application. At 600 °C a mixed spinel structure was only formed for the combination of Cu and Mn, while at 1000 °C all the materials showed mixed spinel formation. The catalysts were applied in three-way catalysis using a reactor with a gas mixture containing CO, NO and O2. All the materials calcined at 600 °C displayed the remarkable ability to oxidize CO with O2 but also to reduce NO with CO, while the pure oxides such as CuO and MnO2 were not able to. The high catalytic activity at 600 °C was attributed to small supported CuO particles present and imperfections in the spinel structure. Calcination at 1000 °C crystallized the structure further which led to a dramatic loss in catalytic activity, although CuAl2O4 and CuFe2O4 still converted some NO. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, H2-Temperatrue Programmed Reduction (H2-TPR), N2-sorption and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).

scholarly journals Precipitated K-Promoted Co–Mn–Al Mixed Oxides for Direct NO Decomposition: Preparation and Properties

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 592 ◽  
Author(s):  
Květa Jirátová ◽  
Kateřina Pacultová ◽  
Jana Balabánová ◽  
Kateřina Karásková ◽  
Anna Klegová ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
No Decomposition ◽  
Temperature Programmed Reduction ◽  
X Ray ◽  
Co2 Desorption ◽  
Metal Nitrates ◽  
Temperature Programmed ◽  
Desorption Method ◽  
Al Oxide

Direct decomposition of nitric oxide (NO) proceeds over Co–Mn–Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co–Mn–Al catalysts prepared by different methods differ from each other? The K-precipitated Co–Mn–Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K2CO3/KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 °C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co–Mn–Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N2 physisorption, FTIR, temperature programmed reduction (H2-TPR), temperature programmed CO2 desorption (CO2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.

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