scholarly journals Structure of LaSrMO4(M = Mn, Fe, Co, Ni, Cu) and their catalytic properties in the total oxidation of hexane

2006 ◽  
Vol 71 (10) ◽  
pp. 1049-1059 ◽  
Author(s):  
H. Zhong ◽  
R. Zeng
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Oxygen Vacancies ◽  
Mixed Oxides ◽  
Ethylenediaminetetraacetic Acid ◽  
Catalytic Properties ◽  
Bet Surface Area ◽  
Total Oxidation ◽  
Catalytic Behavior ◽  
Perovskite Type

Perovskite-type LaSrMO4 (M = Mn, Fe, Co, Ni, Cu) mixed oxides were prepared by the decomposition of amorphous citric and ethylenediaminetetraacetic acid complexes and investigated by the XRD, FTIR, BET, TPR, TPD and XPSmethods. Their catalytic behavior in the total oxidation of hexane was examined. The following activity order was found LaSrCoO4 > LaSrNiO4 > LaSrCuO4 > LaSrFeO4 > LaSrMnO4. This is explained in terms of oxygen vacancies and mobile lattice oxygen, particle size and BET surface area. .

Effect of the Ration of Cu to Mn on the Activity and Stability of Copper-Manganese Mixed-Oxides for the Water Gas Shift Reaction

2013 ◽  
Vol 634-638 ◽  
pp. 518-521 ◽  
Author(s):  
Ke Duan Zhi ◽  
Quan Sheng Liu ◽  
Run Xia He ◽  
Fang Wu ◽  
Ya Gang Zhang ◽  
...  
Keyword(s):  
Surface Area ◽  
Mixed Oxides ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Catalyst Structure ◽  
Catalytic Behavior ◽  
Stable Catalyst ◽  
Copper Manganese ◽  
Shift Reaction ◽  
Water Gas

The effects of Cu/Mn ratio on the activity and stability of Cu-Mn catalysts for the water-gas shift reaction (WGSR) were investigated. Activity tests showed that the Cu-Mn catalyst while the ration of Cu to Mn is 1:1 displayed higher activity and better stability than that of others catalysts. The BET , XRD and TPR results revealed that the Cu-Mn catalyst while the ration of Cu to Mn is 1:1 led to higher surface area, a more stable catalyst structure and suitable reduction performance, in turn leading to better catalytic behavior for the Cu-Mn catalyst.

scholarly journals Surface and Catalytic Properties of NiO and Co3O4 Solids Doped with Cobalt and Nickel Ions

2002 ◽  
Vol 20 (5) ◽  
pp. 467-484
Author(s):  
G.A. El-Shobaky ◽  
A.M. Turky ◽  
A.M. Ghozza
Keyword(s):  
Particle Size ◽  
Thermal Treatment ◽  
Surface Area ◽  
Catalytic Properties ◽  
Excess Oxygen ◽  
Average Particle ◽  
Surface Excess ◽  
Nickel Ions ◽  
Nickel Species ◽  
Cobalt And Nickel

The effects of doping NiO and Co3O4 solids with cobalt and nickel species on their surface and catalytic properties were investigated. The amounts of dopant, in the form of the corresponding nitrate, were varied between 0.5–6.0 mol% cobalt ions and 2.0–6.0 mol% nickel ions. Pure and variously doped solids were subjected to thermal treatment at 300–700°C. The techniques employed were XRD, nitrogen adsorption at −196°C, decomposition of H2O2 at 30–50°C and estimation of the amount of surface excess oxygen on the variously prepared solids as determined by the hydrazine method. The results obtained revealed that the pure and variously doped NiO samples precalcined at 300°C consisted of a finely divided NiO phase having an average particle size of ca. 40 Å. Pure and variously doped Co3O4 specimens preheated at 500°C and 700°C were composed of a Co3O4 phase with a much bigger particle size (230 Å and 350 Å, respectively, for the solids precalcined at 500°C and 700°C). Doping of NiO followed by thermal treatment at 300°C and 500°C resulted in a measurable decrease in its BET surface area (19–23%), while doping of Co3O4 with nickel species followed by heating at 500°C and 700°C brought about a significant increase in its specific surface area (56–60%). Doping each of the NiO and Co3O4 solids with cobalt and nickel species greatly increased the amount of surface excess oxygen and effected a considerable increase in their catalytic activities. This increase was, however, much more pronounced in the case of NiO which attained a value of ca. 100-fold. Doping of NiO with cobalt species followed by thermal treatment at 300°C and 500°C decreased the activation energy (DE) of the catalyzed reaction to an extent proportional to the amount of dopant added. On the other hand, doping of Co3O4 with nickel species followed by thermal treatment at 500°C and 700°C did not change the value of DE. These results suggest that doping of Co3O4 with nickel species did not modify the mechanism of the catalyzed reaction but increased the concentration of catalytically active sites without changing their energetic nature.

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 The Study on the Reaction Order and Kinetics of Total Oxidation Reaction of m-xylene over LaMnO3 Perovskite Catalyst

2018 ◽  
Vol 34 (3) ◽  
Author(s):  
Tran Thi Thu Huyen ◽  
Dang Thi Minh Hue ◽  
Nguyen Thi Tuyet Mai ◽  
Tran Thi Luyen ◽  
Nguyen Thi Lan
Keyword(s):  
Catalytic Activity ◽  
Reaction Order ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Deep Oxidation ◽  
Perovskite Oxide ◽  
Mixed Metal Oxide ◽  
Total Oxidation ◽  
Kinetics Of ◽  
Perovskite Type

Gases of m-xylene is one of the popurlar toxic pollutants in the exhaust gases, it is emitted into the environment from factories and engines because the fuel in the engine does not burn completely. The best solution in order to remove this toxic gases of m-xylene to protect the environment is transforming them completely into CO2 and H2O by catalysts. Perovskite of LaMnO3 is one of the catalysts that was synthesized and studied the catalytic properties in total oxidation of m-xylene in our previous report. Obtained results showed that the LaMnO3 perovskite has good catalytic characterizations such as large surface area and the amount of α-oxygen adsorbed on the catalyst is large too. So, it exhibits a good catalytic activity in total oxidation of m-xylene at relatively low reaction temperature. In present work, the reaction order  and kinetics of this reaction are determined. The obtained results demonstrated that the reaction order value with respect to m-xylene is equal to about 1, to oxygene is proximately equal to 0 and the order of reaction is equal to about 1. Based on reaction order data, it was thought that the pathway of m-xylene oxidation by air oxygen  over LaMnO3 may be followed through which the Langmuir - Hinshelwood mechanism. Keywords Catalyst, perovskite, oxidation, m-xylene, kinetics References [1] Penã M.A and Fierro J.L.G (2001), << Chemical Stuctures and Performance of Perovskite Oxide>>, Chem. Rev, 101, pp 1981-2018. [2] Seiyama T., Yamazoe N. and Eguchi K. (1985), <<Characterization and Activity of some Mixed Metal Oxide Catalysts>>, Ind. Eng. Chem. Prod. Res. Dev., 24, pp. 19-27.[3] [3] Van Santen R. A., Neurock M. (2006), Molecular Heterogeneous catalysis, Wiley – VCH, pp.62-244. [4] Petrovics, Terlecki - Baricevic A., Karanovic Lj., Kirilov - Stefanov P. , Zdujic M., Dondur V., Paneva D., Mitov I., Rakic V. (2008), <<LaMO3 (M = Mg, Ti, Fe) perovskite type oxides : Preparation, Characterization and Catalytic Properties in Methane deep Oxidation>>, Appl. Catal. B, Env., 79, pp. 186-198. [5] Spinicci R., Tofanari A., Faticanti M., Pettiti I. and Porta P. (2001), <<Hexane Total Oxidation on LaMO3 (M = Mn, Co, Fe) perovskite-type oxides>>, J. Mole. Catal., 176, pp. 247-252. [6] Trần Thị Thu Huyền, Nguyễn Thị Minh Hiền, Nguyễn Hữu Phú (2006), <<Study on the preparation of perovskite oxides La1-xSrxMnO3 (x = 0; 0,3; 0,5) by sol - gel citrate method and their catalytic activity for m-xylene toltal oxidation>>, Hội nghị xúc tác và hấp phụ toàn quốc lần thứ IV, Tp. Hồ Chí Minh, Tr. 477-482.[7] Trần Thị Thu Huyền, Nguyễn Thị Minh Hiền, Nguyễn Hữu Phú (2009), <<Nghiên cứu động học của phản ứng oxi hóa hoàn toàn m-xylen trên các xúc tác perovskit LaMnO3 và La0,7A0,3MnO3 (A = Sr, Ca, Mg)>>, Tạp chí Hóa học, T.47 (6A), Tr 132-136.[8] Geoffrey C. Bond, Catherine Louis, David T. Thompson (2006), <<Catalysis by Gold>>, Catalytic Science Series-Vol.6.

scholarly journals Surface and Catalytic Properties of γ-Irradiated Cr2O3/Al2O3 Solids

1997 ◽  
Vol 15 (6) ◽  
pp. 465-476 ◽  
Author(s):  
G.A. El-Shobaky ◽  
A.M. Ghozza ◽  
G.M. Mohamed
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Surface Area ◽  
Pore Volume ◽  
Active Sites ◽  
Catalytic Properties ◽  
Total Pore Volume ◽  
Bet Surface Area ◽  
Two Samples ◽  
Γ Rays

Two samples of Cr2O3/Al2O3 were prepared by mixing a known mass of finely powdered Al(OH)3 with a calculated amount of CrO3 solid followed by drying at 120°C and calcination at 400°C. The amounts of chromium oxide employed were 5.66 and 20 mol% Cr2O3, respectively. The calcined solid specimens were then treated with different doses of γ-rays (20–160 Mrad). The surface and catalytic properties of the different irradiated solids were investigated using nitrogen adsorption at −196°C and the catalysis of CO oxidation by O2 at 300–400°C. The results revealed that γ-rays brought about a slight decrease in the BET surface area, SBET (15%), and in the total pore volume, Vp (20%), of the adsorbent containing 5.66 mol% Cr2O3. The same treatment increased the total pore volume, Vp (36%), and the mean pore radius, r̄ (43%), of the other adsorbent sample without changing its BET surface area. The catalytic activities of both catalyst samples were found to increase as a function of dose, reaching a maximum value at 80–160 Mrad and 40 Mrad for the solids containing 5.66 and 20 mol% Cr2O3, respectively. The maximum increase in the catalytic activity measured at 300°C was 59% and 100% for the first and second catalyst samples, respectively. The induced effect of γ-irradiation on the catalytic activity was an increase in the concentration of catalytically active sites taking part in chemisorption and in the catalysis of CO oxidation by O2 without changing their energetic nature. This was achieved by a progressive removal of surface hydroxy groups during the irradiation process.

The role of oxygen vacancy over ZnCr-layered double oxide in enhancing solar light-driven photocatalytic degradation of bisphenol A

2018 ◽  
Vol 15 (4) ◽  
pp. 226 ◽  
Author(s):  
Meiqing Chen ◽  
Pingxiao Wu ◽  
Qianqian Wei ◽  
Yajie Zhu ◽  
Shanshan Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Bisphenol A ◽  
Photocatalytic Degradation ◽  
Surface Area ◽  
Organic Pollutants ◽  
Oxygen Vacancies ◽  
Solar Light ◽  
X Ray ◽  
Vis Spectroscopy

Environmental contextAn important goal in attempts to degrade environmental organic pollutants is the development of a photocatalyst that is responsive to visible light. We report a facile method for preparing a zinc-based photocatalyst with oxygen vacancies that efficiently degrades bisphenol A under solar light irradiation. The study will stimulate further investigations into the efficacy of other metal oxide nanostructures for the photocatalytic degradation of organic pollutants. AbstractTwo ZnCr-layered double oxides (ZnCr-LDO) were fabricated via different thermal treatment of the ZnCr-layered double hydroxide (ZnCr-LDH) precursor. ZnCr-V-700 and ZnCr-A-700 were obtained at 700 °C under vacuum and air, respectively. As X-ray diffraction revealed, both ZnCr-V-700 and ZnCr-A-700 were made up of ZnO and ZnCr2O4 spinel, and ZnCr-V-700 displayed a lower crystallinity and many uniform particles with oxygen vacancies. Scanning electron microscopy and transmission electron microscopy revealed that the particle size of ZnCr-V-700 was ~30 nm and its disordered crystallinity suggested the existence of oxygen vacancies. Notably, the ZnCr-LDO materials showed remarkably enhanced photocatalytic activity compared to the ZnCr-LDH precursor. ZnCr-V-700 was the most active material and more than 90 % of BPA was degraded after irradiation for 200 min with high mineralisation (up to 37 %). The results of Brunauer–Emmett–Teller surface area analysis, X-ray photoelectron spectroscopy, Raman and UV-vis spectroscopy and electron paramagnetic resonance spectroscopy showed that oxygen vacancies incorporated into ZnCr-V-700 played a key role in improving the photocatalytic performance by enhancing interfacial charge transfer and restricting the charge recombination. In addition, the uniform particle size, larger surface area and the coexistence of ZnO and ZnCr2O4 also played a synergistic role. In conclusion, this work not only provides a facile and low-cost method to prepare photocatalysts for treatment of wastewater containing BPA, but also supplies a new idea for improving the performance of photocatalysts.

Structures and Catalytic Activities of LaSrCoO4 and LaSrCoO3.6F0.4 Mixed Oxides

2011 ◽  
Vol 55-57 ◽  
pp. 1957-1961
Author(s):  
Xiao Mao Yang
Keyword(s):  
Particle Size ◽  
Catalytic Activity ◽  
Oxygen Vacancies ◽  
Mixed Oxides ◽  
Lattice Oxygen ◽  
Gel Method ◽  
Catalytic Activities ◽  
Surface Areas ◽  
Better Than

The perovskite-like LaSrCoO4and LaSrCoO3.6F0.4mixed oxides were prepared by the polyglycol gel method, investigated by using the XRD, TEM, BET, O2-TPD and XPS methods, and used successfully for CO and C3H8oxidization. The results indicate that LaSrCoO4and LaSrCoO3.6F0.4mixed oxides have K2NiF4structure. The catalytic activity of LaSrCoO4is better than that of LaSrCoO3.6F0.4, this is explained in terms of more mobile lattice oxygen, higher content of Co3+, more oxygen vacancies, smaller particle size and larger BET surface areas of LaSrCoO4.

scholarly journals Catalytic Properties of Perovskite-type Mixed Oxides, La1−xSrxCoO3

1982 ◽  
Vol 55 (2) ◽  
pp. 394-399 ◽  
Author(s):  
Teiji Nakamura ◽  
Makoto Misono ◽  
Yukio Yoneda
Keyword(s):  
Mixed Oxides ◽  
Catalytic Properties ◽  
Perovskite Type

Copper-Based Mixed Oxides Catalyst of Water-Gas Shift Reaction for Fuel Cells: The Role of Alkali Charge

2012 ◽  
Vol 268-270 ◽  
pp. 538-541
Author(s):  
Ke Duan Zhi ◽  
Quan Sheng Liu ◽  
Run Xia He ◽  
Fang Wu ◽  
Ya Gang Zhang ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Surface Area ◽  
Mixed Oxides ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Catalyst Structure ◽  
Catalytic Behavior ◽  
Shift Reaction ◽  
Water Gas

The effects of alkali charge on the activity and stability of copper-based mixed oxides catalyst for the water-gas shift reaction (WGSR) were investigated. Activity tests showed that the copper-based mixed oxides catalyst while the 2[NaOH]/[Cu2++Mn2+] is above 1.2 displayed higher activity and better stability than that of others catalysts. The BET , XRD and TPR results revealed that the Cu-Mn catalyst while the 2[NaOH]/[Cu2++Mn2+] is above 1.2 led to higher surface area, a more stable catalyst structure and suitable reduction performance, in turn leading to better catalytic behavior for the Cu-Mn catalyst.

Sign in / Sign up

Export Citation Format

Share Document