scholarly journals Catalytic Activity in CO Oxidation of MnOx Supported on Oxide and Zeolite Carriers

2015 ◽  
Vol 3 (2) ◽  
pp. 54-64
Author(s):  
Larisa Lutsenko ◽  
Ludmila Oleksenko ◽  
German Telbiz ◽  
Victoriia Gerasova
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Diffuse Reflectance ◽  
Active Catalyst ◽  
Previous Treatment ◽  
Catalytic Performance ◽  
Infra Red ◽  
Previously Treated ◽  
Adsorbed Co ◽  
Temperature Programmed

Catalytic activity in CO oxidation was investigated for MnOx-containing materials, prepared by impregnation of SiO2, Al2O3 and zeolites (ZSM-5, ERI). The catalysts were characterized by temperature-programmed reduction (TPR) by hydrogen, diffuse-reflectance UV–Vis (DR UV–Vis) and infra-red (IR) spectroscopy of adsorbed CO. Effect of the previous treatment of the MnOx-containing systems on the catalytic performance has been established. Higher catalytic activity in CO oxidation of the materials treated with air as compared with treated with hydrogen can be explained by presences of manganese ions in +3 and +4 oxidation states. 3%Mn-SiO2 previously treated with air at 350 °C is found to be the most active catalyst among the studied ones. MnOx, CO oxidation, TPR, IR of adsorbed CO, DR UV–Vis

The Different Morphology of Co3O4 Catalysts and Application in the Abatement of Carbon Monoxide

2021 ◽  
Vol 21 (12) ◽  
pp. 6082-6087
Author(s):  
Chih-Wei Tang ◽  
Hsiang-Yu Shih ◽  
Ruei-Ci Wu ◽  
Chih-Chia Wang ◽  
Chen-Bin Wang
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption

The increase of harmful carbon monoxide (CO) caused by incomplete combustion can affect human health even lead to suffocation. Therefore reducing the CO discharged by vehicles or factories is urgent to improve the air quality. The spinel cobalt (II, III) oxide (Co3O4) is an active catalyst for CO abatement. In this study, we tried to fabricate dispersing Co3O4 via the dispersion-precipitation method with acetic acid, formic acid, and oxalic acid as the chelating dispersants. Then, the asprepared samples were calcined at 300 ºC for 4 h to obtain active catalysts, and assigned as Co(A), Co(F) and Co(O) respectively, the amount of the dispersants used are labeled as I (0.12 mole), II (0.03 mole) and III (0.01 mole). For comparison, another CoAP sample was prepared via alkaliinduced precipitation and calcined at 300 ºC. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscope (SEM), and nitrogen adsorption/desorption system, and the catalytic activity focused on the CO oxidation. The influence of chelating dispersant on the performance of abatement of CO was pursued in this study. Apparently, the results showed that the chelating dispersant can influence the catalytic activity of CO abatement. An optimized ratio of dispersant can improve the performance, while excess dispersant lessens the surface area and catalytic performance. The series of Co(O) samples can easily donate the active oxygen since the labile Co–O bonding and indicated the preferential performance than both Co(A) and Co(F) samples. The nanorod Co(O)-II showed preferential for CO oxidation, T50 and T90 approached 96 and 127 ºC, respectively. Also, the favorable durability of Co(O)-II sample maintains 95% conversion still for 50 h at 130 ºC and does not emerge deactivation.

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.

Oxygen Radicals Occlusion/Release Behavior of Nanoporous Aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4)

2006 ◽  
Vol 45 ◽  
pp. 2105-2109
Author(s):  
Makoto Nagashima ◽  
Daisuke Hirabayashi ◽  
Kenzi Suzuki
Keyword(s):  
Catalytic Activity ◽  
Oxygen Content ◽  
Oxygen Radicals ◽  
Catalytic Performance ◽  
Oxygen Release ◽  
Release Behavior ◽  
Temperature Programmed Reduction ◽  
Temperature Programmed Oxidation ◽  
Temperature Range ◽  
Temperature Programmed

Oxygen radicals occlusion / release behavior of nanoporous aluminosilicate, Ca12Al14-XSiXO33+0.5X (0≦X≦4), synthesized under different condition was examined by the temperature programmed reduction (TPR) in an atmosphere of hydrogen in the temperature range of 200-1000°C and temperature programmed oxidation (TPO) measurement at 800°C. From the TPR results of Ca12Al14O33 (X=0) and Ca12Al10Si4O35 (X=4), it was found that there were three oxygen release peaks, denoted as α, β and γ, on each sample and the peaks appeared in the temperature range 300-420°C, 420-600°C, and 600-750°C, respectively. The oxygen contents of α and γ of samples were almost the same. However, the oxygen content of β in the sample with x = 4 was much larger, almost double, compared to that in x = 0. From the TPR, TPO results and catalytic performance, it was concluded that the oxygen content of β peak strongly influenced the catalytic activity of the nanoporous aluminosilicate in the propylene combustion.

High-heat treatment enhanced catalytic activity of CuO/CeO2 catalysts with low CuO content for CO oxidation

2020 ◽  
Vol 10 (15) ◽  
pp. 5256-5266 ◽  
Author(s):  
Jihang Yu ◽  
Qiangsheng Guo ◽  
Xiuzhen Xiao ◽  
Haifang Mao ◽  
Dongsen Mao ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
High Heat ◽  
Catalytic Performance

CuO/CeO2 catalysts with low CuO content and calcined at 800 °C exhibited better catalytic performance than those calcined at 500 °C. The coordinatively unsaturated copper atoms were proved to be the main active sites in the CuO/CeO2 catalysts.

Nanosized Pt-Co Catalysts for the Preferential CO Oxidation

2006 ◽  
Vol 6 (11) ◽  
pp. 3567-3571 ◽  
Author(s):  
Eun-Yong Ko ◽  
Eun Duck Park ◽  
Kyung Won Seo ◽  
Hyun Chul Lee ◽  
Doohwan Lee ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Peak Shift ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Preferential Co Oxidation ◽  
X Ray ◽  
Co Catalysts ◽  
Transmission Electron ◽  
Temperature Programmed

The preferential CO oxidation in the presence of excess hydrogen was studied over Pt-Co/γ-Al2O3. CO chemisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectrometer (EDX) and temperature programmed reduction (TPR) were conducted to characterize active catalysts. The catalytic activity for CO oxidation and methanation at low temperatures increased with the amounts of cobalt in Pt-Co/γ-Al2O3. This accompanied the TPR peak shift to lower temperatures. The optimum molar ratio between Co and Pt was determined to be 10. The co-impregnated Pt-Co/γ-Al2O3 appeared to be superior to Pt/Co/γ-Al2O3 and Co/Pt/γ-Al2O3. The reductive pretreatment at high temperature such as 773 K increased the CO2 selectivity over a wide reaction temperature. The bimetallic phase of Pt-Co seems to give rise to high catalytic activity in selective oxidation of CO in H2-rich stream.

One-Step FSP Synthesis of Nanocrystalline Fe/Al2O3 and Fe-Ce/Al2O3 Catalyst for CO2 Hydrogenation Reaction

2018 ◽  
Vol 916 ◽  
pp. 134-138 ◽  
Author(s):  
Kanyarat Piriyasurawong ◽  
Sunthon Piticharoenphun ◽  
Okorn Mekasuwandumrong
Keyword(s):  
Catalytic Activity ◽  
Iron Oxide ◽  
Catalytic Performance ◽  
Hydrogenation Reaction ◽  
Flame Spray ◽  
One Step ◽  
Temperature Programmed ◽  
The One ◽  
Long Chain ◽  
Chain Hydrocarbon

Nanocrystalline Fe/Al2O3and Fe-Ce/Al2O3catalysts doped with various amounts of cerium were prepared using the one-step flame spray pyrolysis (FSP) technique. The characterization of the catalysts was measured by several methods such as X-ray diffraction, nitrogen physisorption and hydrogen temperature programmed reduction (H2-TPR) techniques. The results revealed that the FSP-made catalyst exhibited the characteristic pattern of FeAl2O4phase without any phases of aluminum or iron oxide. In addition, cerium (Ce) dopant did not alter crystal structure at low content. However, 7 wt% content of cerium dopant resulted in the formation of ceria (CeO) and iron oxide (Fe2O3) phase. The catalytic performance of the FSP-made catalyst was tested in carbon dioxide hydrogenation for selective production of long chain hydrocarbon, and was compared to conventional impregnation-made catalysts. In the comparison, the FSP-made catalyst exhibited lower catalytic activity but possessed a higher long chain hydrocarbon selectivity. After doping with Ce, the catalytic activity was improved while the hydrocarbon selectivity was decreased and shifted to the short chain hydrocarbon product. In the case of conventional-made catalysts, the activity remained unchanged but the hydrocarbon selectivity was decreased. Among all catalysts, the FSP-made Fe-Ce/Al2O3catalyst with 3% Ce-promoted catalyst exhibited the best performance in terms of selectivity to long chain hydrocarbon.

Preparation of Au and Au-Ce Catalysts Supported on Acid-Activated Bentontie and its Catalytic Performance

2011 ◽  
Vol 287-290 ◽  
pp. 1704-1707
Author(s):  
Rong Bin Zhang ◽  
Liu Jing Yao ◽  
Yan Ju
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Surface Area ◽  
Pore Volume ◽  
Catalytic Performance ◽  
Substantial Improvement ◽  
Au Catalyst ◽  
Activated Bentonite

Acid-activated by H2SO4was applied to modify bentonite. Acid-activated bentonite supported Au catalyst was prepared by deposition-precipitation and compared with SiO2supported one. CTAB was used to modify the surface of acid-activated bentonite. Au-Ce/bentontie catalyst was prepared by adding Ce into catalyst as assistant. CO oxidation was used to evaluate the catalytic activity of samples. These samples were characterized by BET, XRD, ICP and CO-TPD. The activity results showed that Au/Bentonite was more active than Au/SiO2. The BET results showed that the surface area and pore volume of acid-activated bentontie had a substantial improvement. Using the bentontie acid-activated by 30wt%H2SO4as supporter，the Au-Ce catalyst has a better catalytic performance than Au catalyst.

scholarly journals Influence of Copper on the Catalytic Activity of Supported Rhodium Catalysts in the Reactions of CO Oxidation and NO Reduction

2017 ◽  
Vol 4 (4) ◽  
pp. 265
Author(s):  
L.A. Petrov ◽  
J. Soria ◽  
R. Cataluna
Keyword(s):  
Catalytic Activity ◽  
Thermal Treatment ◽  
Low Temperature ◽  
Co Oxidation ◽  
No Reduction ◽  
Promoting Effect ◽  
Catalytic Activities ◽  
Cu Catalysts ◽  
Temperature Programmed ◽  
Positive Effect

<p>The catalytic activity of Cu, Rh, and Rh/Cu, catalysts supported on Al<sub>2</sub>O<sub>3</sub>, CeO<sub>2</sub> and CeO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> in reactions of CO oxidation and NO reduction has been studied in temperature-programmed regime. Addition of Cu to Rh catalysts decreases temperature at which 5 and 50% degree of conversion, while end of reaction temperature is not influenced by presence of Cu. The presence of Cu has positive effect on the activity of Rh containing catalysts in the low temperature region. Cu has noticeable promoting effect mainly for the catalytic activity in the reaction of CO oxidation and in smaller extent for the reaction of NO reduction. Preliminary redox treatment of the catalysts decreases the light off temperature in the reactions of CO oxidation and in NO reduction. Thermal treatment at temperatures up to 973 K does not have sensible effect on the catalytic activities of all studied catalysts. Calcination at 1073 K, however, strongly decreases the catalytic activity of Rh/Cu/CeO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> catalysts.</p>

Catalytic Performance of Supported Bimetallic Catalysts for Complete Oxidation of Toluene

2021 ◽  
Vol 21 (7) ◽  
pp. 4060-4066
Author(s):  
Sang-Chul Jung ◽  
Young-Kwon Park ◽  
Ho-Young Jung ◽  
Sang Chai Kim
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Bimetallic Catalysts ◽  
Xrd Analysis ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
Complete Oxidation ◽  
Transmission Electron ◽  
The Difference ◽  
Temperature Programmed

The complete oxidation of toluene (as a model volatile organic compound) was studied to determine the influence of adding a transition metal (Mn, Cr, Fe, Co, and Ni) to the 5 Cu/Al catalyst. The physcochemical properties of the catalysts were characterized by Brunauer–Emmett–Teller (BET) surface area analysis, X-ray diffraction (XRD) analysis, field emission transmission electron microscopy (FE/TEM), and hydrogen temperature programmed reduction (H2-TPR). The catalytic activity of the supported bimetallic catalysts followed the order: 5Cu-5Mn/Al > 5Cu-5Cr/Al > 5Cu-5Fe/Al > 5Cu-5Co/Al > 5Cu > 5Cu-5Ni/Al, based on the temperature for T90 of toluene conversion (T90). Two different reaction mechanisms (mixing and the synergistic effect) were operative in the supported bimetallic catalysts except for the 5Cu–5Mn/Al and 5Cu–5Ni/Al catalysts, on the basis of the reaction temperature. The difference between the electronegativity of copper and the added transition metal was associated with the catalytic activity.

scholarly journals Preferential Oxidation of CO over CoFe2O4 and M/CoFe2O4 (M = Ce, Co, Cu or Zr) Catalysts

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Mehdi Béjaoui ◽  
Abdelhakim Elmhamdi ◽  
Laura Pascual ◽  
Patricia Pérez-Bailac ◽  
Kais Nahdi ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Preferential Oxidation Of Co ◽  
Transmission Electron ◽  
Low Temperature Co Oxidation ◽  
Temperature Programmed ◽  
Diffuse Reflectance Infrared

CoFe2O4 prepared by sol-gel has been examined with respect to its catalytic performance for preferential CO oxidation in a H2-rich stream. In turn, the promoting effects of incorporation of Ce, Co, Cu, and Zr by impregnation on the surface of CoFe2O4 on the process are examined as well. The catalysts have been characterized by N2 adsorption, X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), temperature programmed reduction (TPR), and X-ray photoelectron spectra (XPS), as well as diffuse reflectance infrared DRIFTS under reaction conditions with the aim of establishing structure/activity relationships for the mentioned catalyst/process. It is shown that while the presence of the various metals on CoFe2O4 hinders a low temperature CO oxidation process, it appreciably enhances the activity above 125 °C. This is basically attributed to the surface modifications, i.e. cobalt oxidation, induced in CoFe2O4 upon introduction of the metals. In turn, no methanation activity is observed in any case except for the copper-containing catalyst, in which achievement of reduced states of cobalt appears most favored.

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