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.

Formation of mixed oxide powders in flames: Part II. SiO2−GeO2 and Al2O3−TiO2

1992 ◽  
Vol 7 (7) ◽  
pp. 1870-1875 ◽  
Author(s):  
Cheng-Hung Hung ◽  
Philippe F. Miquel ◽  
Joseph L. Katz
Keyword(s):  
Light Scattering ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Electrophoretic Method ◽  
X Ray ◽  
Oxide Powders ◽  
Flame Burner ◽  
Carbon Coated ◽  
Oxide Particles ◽  
Counterflow Diffusion Flame

SiO2−GeO2 and Al2O3−TiO2 mixed oxide powders were synthesized using a counterflow diffusion flame burner. SiCl4, GeCl4, Al(CH3)3, and TiCl4 were used as source materials for the formation of oxide particles in hydrogen-oxygen flames. In situ particle sizes were determined using dynamic light-scattering. Powders were collected using two different methods, a thermophoretic method (particles are collected onto carbon coated TEM grids) and an electrophoretic method (particles are collected onto stainless steel strips). Their size, morphology, and crystalline form were examined using a transmission electron microscope and an x-ray diffractometer. A photomultiplier at 90° to the argon ion laser beam was used to measure the light-scattering intensity. The formation of the mixed oxides was investigated using Si to Ge and Al to Ti ratios of 3:5 and 1:1, respectively. Heterogeneous nucleation of the SiO2 on the surface of the GeO2 was observed. In Al2O3−TiO2 mixtures, both oxide particles form at the same temperature. X-ray diffraction analysis of particles sampled at temperatures higher than 1553 K showed the presence of rutile, γ–Al2O3, and aluminum titanate. Although the particle formation process for SiO2−GeO2 is very different from that for Al2O3−TiO2, both mixed oxides result in very uniform mixtures.

scholarly journals Catalytic Combustion of Low Concentration Methane over Catalysts Prepared from Co/Mg-Mn Layered Double Hydroxides

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Hongfeng Liu ◽  
Xingrui Fu ◽  
Xiaole Weng ◽  
Yue Liu ◽  
Haiqiang Wang ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Layered Double Hydroxides ◽  
Catalytic Combustion ◽  
Mixed Oxides ◽  
Oxygen Mobility ◽  
Catalytic Combustion Of Methane ◽  
Redox Ability ◽  
Double Hydroxides ◽  
Mn Oxides

A series of Co/Mg-Mn mixed oxides were synthesized through thermal decomposition of layered double hydroxides (LDHs) precursors. The resulted catalysts were then subjected for catalytic combustion of methane. Experimental results revealed that the Co4.5Mg1.5Mn2LDO catalyst possessed the best performance with theT90=485°C. After being analyzed via XRD, BET-BJH, SEM, H2-TPR, and XPS techniques, it was observed that the addition of cobalt had significantly improved the redox ability of the catalysts whilst certain amount of magnesium was essential to guarantee the catalytic activity. The presence of Mg was helpful to enhance the oxygen mobility and, meanwhile, improved the dispersion of Co and Mn oxides, preventing the surface area loss after calcination.

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.

Calcined Ni—Al layered double hydroxide as a catalyst for total oxidation of volatile organic compounds: Effect of precursor crystallinity

2007 ◽  
Vol 61 (2) ◽  
Author(s):  
Z. Mikulová ◽  
P. Čuba ◽  
J. Balabánová ◽  
T. Rojka ◽  
F. Kovanda ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrothermal Treatment ◽  
Layered Double Hydroxide ◽  
Mixed Oxides ◽  
Slight Effect ◽  
Total Oxidation ◽  
Volatile Organic ◽  
Double Hydroxide ◽  
Short Time ◽  
Oxidation Of Ethanol

AbstractThe effect of hydrothermal treatment on properties (crystallinity, porous structure, reducibility, acidity, basicity, and catalytic activity and selectivity in toluene and ethanol total oxidation) of Ni—Al layered double hydroxide precursors and related mixed oxides was examined. The hydrothermal treatment increased considerably both the content of crystalline phase and LDH crystallite size. On the other hand, only a slight effect of the precursor hydrothermal treatment on crystallinity of the related Ni—Al mixed oxides obtained by calcination at 450°C was observed. The reducibility of NiO particles appeared to be hindered considerably compared to the reducibility of pure NiO. Catalytic activity of the Ni—Al mixed oxides prepared from the precursors hydrothermally treated for a short time (4 h) was the highest. The highest amount of acetaldehyde formed during the total oxidation of ethanol, i.e. the worst selectivity was found for the calcined Ni—Al LDH without hydrothermal treatment.

Catalytic properties of copper–manganese mixed oxides prepared by coprecipitation using tetramethylammonium hydroxide

2014 ◽  
Vol 4 (10) ◽  
pp. 3713-3722 ◽  
Author(s):  
Hisahiro Einaga ◽  
Akihiro Kiya ◽  
Satoru Yoshioka ◽  
Yasutake Teraoka
Keyword(s):  
Aqueous Solution ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Oxide Catalysts ◽  
Tetramethylammonium Hydroxide ◽  
Mixed Oxide Catalysts ◽  
Metal Nitrates ◽  
Copper Manganese ◽  
Coprecipitation Technique

Copper–manganese (Cu–Mn) mixed oxide catalysts were prepared by a coprecipitation technique from metal nitrates in aqueous solution using tetramethylammonium hydroxide (TMAH) as a pH regulator.

Porous Mn–Co mixed oxide nanorod as a novel catalyst with enhanced catalytic activity for removal of VOCs

2014 ◽  
Vol 56 ◽  
pp. 134-138 ◽  
Author(s):  
Wenxiang Tang ◽  
Xiaofeng Wu ◽  
Shuangde Li ◽  
Wenhui Li ◽  
Yunfa Chen
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxide ◽  
Novel Catalyst

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.

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.

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