Catalytic activity of Mg–Al hydrotalcites and derived mixed oxides for imination reactions via an oxidative-dehydrogenation mechanism

2020 ◽  
Vol 44 (21) ◽  
pp. 8859-8868
Author(s):  
Naresh Vala ◽  
Pradyuman A. Joshi ◽  
Manish Mishra
Keyword(s):  
Catalytic Activity ◽  
Oxidative Dehydrogenation ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Tandem Reactions ◽  
Dehydrogenation Mechanism

A Mg–Al hydrotalcite derived mixed oxide (Mg/Al ratio = 3.0) showed excellent catalytic activity in imination and tandem reactions via an oxidative-dehydrogenation mechanism.

Activity studies of vanadium, iron, carbon and mixed oxides based catalysts for the oxidative dehydrogenation of ethylbenzene to styrene: a review

2015 ◽  
Vol 5 (12) ◽  
pp. 5062-5076 ◽  
Author(s):  
Itika Kainthla ◽  
Jayesh T. Bhanushali ◽  
Rangappa S. Keri ◽  
Bhari Mallanna Nagaraja
Keyword(s):  
Oxidative Dehydrogenation ◽  
Mixed Oxide ◽  
Active Carbon ◽  
Mixed Oxides ◽  
Oxide Catalysts ◽  
Mixed Oxide Catalysts ◽  
Vanadium Iron ◽  
Dehydrogenation Of Ethylbenzene ◽  
Oxidative Dehydrogenation Of Ethylbenzene ◽  
Carbon Based

The activity of V, Fe and carbon based catalysts depends on V5+, Fe3+and active carbon sites. The mixed oxide catalysts show superior activity than individual oxides.

Rod-like CuMnOx transformed from mixed oxide particles by alkaline hydrothermal treatment as a novel catalyst for catalytic combustion of toluene

2016 ◽  
Vol 18 (33) ◽  
pp. 22794-22798 ◽  
Author(s):  
W. B. Li ◽  
Z. X. Liu ◽  
R. F. Liu ◽  
J. L. Chen ◽  
B. Q. Xu
Keyword(s):  
Catalytic Activity ◽  
Hydrothermal Treatment ◽  
Mixed Oxide ◽  
Catalytic Combustion ◽  
Mixed Oxides ◽  
Copper Manganese ◽  
Oxide Particles ◽  
Novel Catalyst

Rod-like copper manganese mixed oxides by alkaline hydrothermal treatment exhibit superior catalytic activity toward toluene combustion at 210 °C.

scholarly journals Direct Decomposition of NO over Co-Mn-Al Mixed Oxides: Effect of Ce and/or K Promoters

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 808
Author(s):  
Květa Jirátová ◽  
Kateřina Pacultová ◽  
Kateřina Karásková ◽  
Jana Balabánová ◽  
Martin Koštejn ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Chemical Properties ◽  
Surface Concentration ◽  
Direct Decomposition ◽  
No Decomposition ◽  
High Catalytic Activity ◽  
Active Components ◽  
Mixed Oxide Catalysts

Co-Mn-Al mixed oxides promoted by potassium are known as active catalysts for the direct decomposition of nitric oxide (NO). In this study, the answer to the following question has been considered: does the presence of cerium in K-promoted Co-Mn-Al catalysts substantially affect the physical-chemical properties, activity, and stability in direct NO decomposition? The Co-Mn-Al, Co-Mn-Al-Ce, and Co-Mn-Al-Ce-K mixed oxide catalysts were prepared by the precipitation of corresponding metal nitrates with a solution of Na2CO3/NaOH, followed by the washing of the precipitate and calcination. Two other catalysts were prepared by impregnation of the Ce-containing catalysts with Co and Co+K nitrates. After calcination, the solids were characterized by chemical analysis, XRD, N2 physisorption, FTIR, temperature-programmed reduction, CO2 and O2 desorption (H2-TPR, CO2-TPD, O2-TPD), and X-ray photoelectron spectrometry (XPS). Cerium and especially potassium occurring in the catalysts affected the basicity, reducibility, and surface concentration of active components. Adding cerium itself did not contribute to the increase in catalytic activity, whereas the addition of cerium and potassium did. Catalytic activity in direct NO decomposition depended on combinations of both reducibility and the amount of stronger basic sites determined in the catalysts. Therefore, the increase in cobalt concentration itself in the Co-Mn-Al mixed oxide catalyst does not determine the achievement of high catalytic activity in direct NO decomposition.

A Novel Active Ni-Ce-Al-Mixed Oxide Catalysts for Oxidative Dehydrogenation of Propane

2013 ◽  
Vol 724-725 ◽  
pp. 1098-1102 ◽  
Author(s):  
A. Ruheng ◽  
Jiang Wang ◽  
Zhao Ri Ge Tu Bao
Keyword(s):  
Oxidative Dehydrogenation ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
High Surface ◽  
High Surface Area ◽  
Oxide Catalysts ◽  
Coke Deposition ◽  
Oxidative Dehydrogenation Of Propane ◽  
Mixed Oxide Catalysts ◽  
Wide Range

Ni-Ce-Al layered double hydroxides (LDHs) with various Ni:Ce:Al molar ratios (3: 0.1:0.9, 3:0.2:0.8 and 3:0.5:0.5) were prepared by Co-precipitation. Ce can replace Al in a wide range of Ce/Al ratios to form Ni-Ce-Al-LDH with the unique layered structure of hydrotalcite. After the calcined at 600°C, LDHs samples were converted to mesoporous NiO-CeO2mixed oxides with a high surface area. The Ni-Ce-Al mixed oxide catalysts exhibit superior catalytic activity in oxidative dehydrogenation of propane and the excellent activities were attributed to mesoporous structure and the suppression of coke deposition.

Ni–Nb mixed oxides: One-pot synthesis and catalytic activity for oxidative dehydrogenation of ethane

2014 ◽  
Vol 255 ◽  
pp. 185-194 ◽  
Author(s):  
José Santander ◽  
Eduardo López ◽  
Alejandra Diez ◽  
Mariana Dennehy ◽  
Marisa Pedernera ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Oxidative Dehydrogenation ◽  
Mixed Oxides ◽  
One Pot ◽  
One Pot Synthesis ◽  
Oxidative Dehydrogenation Of Ethane

scholarly journals Influence of Vanadium Oxidation States on the Performance of V-Mg-Al Mixed-Oxide Catalysts for the Oxidative Dehydrogenation of Propane

2019 ◽  
Vol 54 (2) ◽  
Author(s):  
Leticia Schacht ◽  
Juan Navarrete ◽  
Persi Schacht ◽  
Marco A. Ramírez
Keyword(s):  
Catalytic Activity ◽  
Oxidative Dehydrogenation ◽  
Oxidation State ◽  
Mixed Oxide ◽  
Catalytic Performance ◽  
Oxide Catalysts ◽  
Oxidative Dehydrogenation Of Propane ◽  
Mixed Oxide Catalysts ◽  
Before And After ◽  
Temperature Programmed

V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %). Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction (TPR). The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly on vanadium oxidation state.

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.

Phase Identification in Mixed Oxide Capacitors Using Electron Backscatter Diffraction and X-Ray Diffraction

2000 ◽  
Vol 6 (S2) ◽  
pp. 944-945
Author(s):  
P. M. Adams ◽  
C. T. Hoskinson ◽  
R. Witt
Keyword(s):  
Dielectric Properties ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Electron Backscatter Diffraction ◽  
Phase Identification ◽  
Electronic Systems ◽  
Oxide Ceramic ◽  
Backscatter Diffraction ◽  
Titanium Silicon ◽  
New Phase

A group of mixed oxide ceramic capacitors used in several electronic systems recently failed as a result of voltage breakdown in the specified test ranges. These capacitors consist predominantly of mixed oxides of magnesium, titanium, silicon and aluminum (with minor amounts of strontium and calcium) and contain palladium mesh electrodes. Preliminary results suggest that phase transformations have occurred in some lots of capacitors that have been over-fired as a result of a manufacturing change. Several years’ production of capacitors has potentially been affected. The formation of a phase with inferior dielectric properties, and which can exhibit semiconducting properties (P/N junction), probably resulted in the failure of the capacitors. This new phase is typically rich in strontium and is only present at levels of several volume percent. The low concentration of this phase has made its identification difficult. If this new phase could be identified it might be possible to determine/establish if its dielectric properties are consistent with the proposed failure mechanism.

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