scholarly journals Physical Properties and Selective CO Oxidation of Coprecipitated CuO/CeO2Catalysts Depending on the CuO in the Samples

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Akkarat Wongkaew ◽  
Wichai Kongsi ◽  
Pichet Limsuwan
Keyword(s):  
Physical Properties ◽  
Co Oxidation ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
High Dispersion ◽  
X Ray Diffraction ◽  
Selective Co Oxidation ◽  
Co Conversion ◽  
Low Degree ◽  
Crystallite Sizes

This paper investigates the effects of CuO contents in the CuO-CeO2catalysts to the variation in physical properties of CuO/CeO2catalysts and correlates them to their catalytic activities on selective CO oxidation. The characteristic of crystallites were revealed by X-ray diffraction, and their morphological developments were examined with TEM, SEM, and BET methods. Catalytic performance of catalysts was investigated in the temperature range of 90–240°C. The results showed that the catalyst was optimized at CuO loading of 20 wt.%. This was due to the high dispersion of CuO, high specific surface area, small crystallite sizes, and low degree of CuO agglomeration. Complete CO conversion with near 100% selectivity was achieved at a temperature below 120°C. The optimal performance was seen as a balance between CuO content and dispersion observed with growth, morphology, and agglomeration of nanostructures.

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 Highly Reducible Nanostructured CeO2 for CO Oxidation

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 535 ◽  
Author(s):  
Gang Feng ◽  
Weining Han ◽  
Zhimiao Wang ◽  
Fang Li ◽  
Wei Xue
Keyword(s):  
Electron Microscope ◽  
Co Oxidation ◽  
Hydrothermal Process ◽  
Textural Properties ◽  
Space Velocity ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Co Conversion ◽  
Structure Morphology ◽  
Adsorption Desorption

Ceria in nanoscale with different morphologies, rod, tube and cube, were prepared through a hydrothermal process. The structure, morphology and textural properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and isothermal N2 adsorption-desorption. Ceria with different morphologies were evaluated as catalysts for CO oxidation. CeO2 nanorods showed superior activity to the others. When space velocity was 12,000 mL·gcat−1·h−1, the reaction temperature for 90% CO conversion (T90) was 228 °C. The main reason for the high activity was the existence of large amounts of easily reducible oxygen species, with a reduction temperature of 217 °C on the surface of CeO2 nanorods. Another cause was their relatively large surface area.

Effect of Calcination Temperatures of Cu/CeO2-Containing Co on Physiochemical Properties and Catalytic Activity to Selective CO Oxidation

2015 ◽  
Vol 1131 ◽  
pp. 175-181 ◽  
Author(s):  
Pornthip Aunbamrung ◽  
Akkarat Wongkaew
Keyword(s):  
Co Oxidation ◽  
Mesoporous Structure ◽  
Selective Co Oxidation ◽  
Calcination Temperatures ◽  
Surface Areas ◽  
Type Iv ◽  
Negative Effect ◽  
Crystallite Sizes ◽  
Co Precipitation ◽  
Shift Reaction

The CuO/CeO2-Co3O4 catalysts were prepared via co-precipitation at different calcination temperatures and evaluated catalytic activities in the reaction of selective CO oxidation. The catalysts were characterized by BET, XRD and FESEM-EDX techniques. As determined by BET studies, the catalysts have type IV adsorption isotherm which indicated mesoporous structure. An increase in calcination temperatures decreased the specific surface areas of the catalysts. XRD was used for determination of crystallite sizes of each oxide. It was found that CuO and Co3O4 existed in highly dispersed at every calcination temperatures. For CeO2, an increase in calcination temperatures increased the crystallite sizes. Surface morphology of the catalysts was also investigated by FESEM. The catalyst calcined at 500°C showed the highest performance to completely convert CO to CO2 at 150°C. Furthermore, the effect of CO2 and H2O to activity of catalyst was studied. The result showed that both CO2 and H2O has negative effect to activity of catalyst. CO conversion and selectivity decreased to 93.8% and 48.5% at 210°C, respectively. This may be due to the adsorption of CO2 and H2O molecules on active site and due to the reverse water gas shift reaction occurred at temperature above 190°C.

Evaluation of NiFe2O4 Spinel, Synthesized by Combustion Reaction, as a Catalyst for Selective CO Oxidation

2010 ◽  
Vol 660-661 ◽  
pp. 771-776 ◽  
Author(s):  
P.T.A. Santos ◽  
Hélio Lucena Lira ◽  
Lucianna Gama ◽  
F. Argolo ◽  
Heloysa Martins Carvalho Andrade ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Co Oxidation ◽  
Spinel Phase ◽  
Vitreous Silica ◽  
Combustion Reaction ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Selective Co Oxidation ◽  
Selective Reaction ◽  
Transmission Electron

The selective reaction of CO oxidation (PROX) was named as the most attractive way to reduce the CO concentration, thereby purifying the hydrogen. The aim of this work is to make the structural and morphologic characterization of the NiFe2O4 spinel synthesized by combustion reaction, using glycine as fuel, and to evaluate as catalyst in the reaction of selective oxidation of carbon monoxide in the presence of hydrogen, oxygen and carbon monoxide. The powder was prepared by using a vitreous silica crucible on a hot plate at 480°C and according to stoichiometry established by theory of propellants and explosive. The powder was characterized by X-ray diffraction (XRD), FTIR, textural analyses, transmission electron microscopy (TEM) and catalytic measurements. The results from XRD show characteristic peaks of spinel phase without presence of secondary phases. The morphologic results show surface area of 3.1 m2/g and particle size calculated by TEM of 21.72 nm. The catalyst was active and selective for O2, reaching 100% of conversion.

Preparation of Highly Dispersion CuO/MCM-41 Catalysts for CO2 Hydrogenation

2019 ◽  
Vol 19 (6) ◽  
pp. 3218-3222 ◽  
Author(s):  
Lin Li ◽  
Chen Zhang ◽  
Xinqing Chen ◽  
Peng Gao ◽  
Jian Sun ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Catalytic Performance ◽  
High Dispersion ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Transmission Electron ◽  
Optimum Reaction ◽  
Mcm 41 ◽  
Hydrogenation Of Co

CuO/MCM-41 catalyst was synthesized by a simple method with the modification of ethylene glycol (EG) and characterized by powder X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM) and transmission electron microscope (SEM). Its catalytic performance in the hydrogenation of CO2 to methanol was also investigated. The results indicated that the as-synthesized CuO/MCM-41-EG catalyst took the properties of high dispersion, small particle size and high surface area, and then showed catalytic performance for the CO2 hydrogenation to methanol. At the optimum reaction temperature of 240 °C, the CuO/MCM-41-EG catalyst gave 15% CO2 conversion and 35% methanol selectivity.

Biotemplate Synthesis of Porous Ceria Fiber and Study on its Catalytic Performance

2013 ◽  
Vol 745-746 ◽  
pp. 491-498 ◽  
Author(s):  
Feng Chen ◽  
Cheng Bao Liu ◽  
Zhi Gang Chen
Keyword(s):  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Nitrogen Absorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hierarchical Porous ◽  
Bet Method ◽  
High Resolution Tem ◽  
Crystallite Diameter

Hierarchical porous ceria with nanocrystalline was successfully synthesized using filter paper as biotemplate. Unique biomorphic microstructures were characterized by Field Emission Scanning Electron Microscope (FESEM), transmission electron microscopy (TEM) and nitrogen absorption-desorption technique. The obtained ceria material showed the repetitious biomimetic structure consisting of fibre with diameter of ca. 1-3 μm and nanopores which had 2-4 nm apertures. The small crystallite diameter (6-8 nm) and the high specific surface area (71.3 m2·g-1) of porous CeO2 were measured by wide-angle X-ray Diffraction (XRD), high resolution TEM (HRTEM) and the BET method. While the concentration of acid fuchsine was 20 mg/L, the porous sample had a higher decoloring rate in a shorter time than others. The decoloring rate can reach 100% after 200 min.

Nano-Sized Au/CeO2 Catalysts for Total and Selective CO Oxidation

2007 ◽  
Vol 124-126 ◽  
pp. 1749-1752 ◽  
Author(s):  
Eun Yong Ko ◽  
Eun Duck Park ◽  
Hyun Chul Lee ◽  
Doo Hwan Lee ◽  
Soon Ho Kim
Keyword(s):  
Co Oxidation ◽  
Metallic Gold ◽  
Precipitation Method ◽  
Edge Structure ◽  
Pretreatment Condition ◽  
Selective Co Oxidation ◽  
Transmission Electron ◽  
Co Conversion ◽  
Temperature Programmed ◽  
Co Precipitation

Au/CeO2 catalysts prepared by a deposition-precipitation and a co-precipitation method were applied to CO oxidation in the absence and presence of hydrogen. The transmission electron microscope (TEM), the temperature programmed reduction (TPR), and the X-ray absorption near edge structure (XANES) were conducted to probe structural and electronic properties of gold. Au2O3 was determined to be mainly present when Au/CeO2 was prepared by a deposition-precipitation method. However, the metallic gold was observed in a co-precipitated Au/CeO2 catalyst. Au/CeO2 containing oxidized gold species, prepared by a deposition-precipitation method, showed the decreasing CO conversion with a reaction time, which accompanied the reduction of gold from Au(+3) to Au(0). However, co-precipitated Au/CeO2 showed the stable CO conversion. The effect of pretreatment condition on CO oxidation was also examined. These results support that Au/CeO2 catalyst containing oxidized gold species was superior to Au/CeO2 catalyst containing the metallic gold for CO oxidation. This Au/CeO2 catalyst was also active for the selective CO oxidation in the presence of hydrogen.

Facile synthesis of meso-structured Pd/FeOx and its highly catalytic performance for low temperature CO oxidation under ambient conditions

RSC Advances ◽  
2015 ◽  
Vol 5 (27) ◽  
pp. 20650-20655 ◽  
Author(s):  
Liang Li ◽  
Gengnan Li ◽  
Yuan Yuan ◽  
Yongsheng Li
Keyword(s):  
Low Temperature ◽  
Co Oxidation ◽  
Catalytic Performance ◽  
Ambient Condition ◽  
Ambient Conditions ◽  
Facile Synthesis ◽  
Co Conversion ◽  
Low Temperature Co Oxidation ◽  
Oxidation Properties

Meso-structured Pd/FeOx material exhibit excellent low temperature CO oxidation properties under ambient condition. Complete CO conversion could be achieved at as low as 0 °C, when 2.5 vol% H2O was introduced into the feed gas.

scholarly journals Fabrication of CeO2–MO x (M = Cu, Co, Ni) composite yolk–shell nanospheres with enhanced catalytic properties for CO oxidation

2017 ◽  
Vol 8 ◽  
pp. 2425-2437 ◽  
Author(s):  
Ling Liu ◽  
Jingjing Shi ◽  
Hongxia Cao ◽  
Ruiyu Wang ◽  
Ziwu Liu
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Catalytic Performance ◽  
Ethanol Solution ◽  
Oxidation Catalyst ◽  
Synthesis Process ◽  
Oxide Systems ◽  
Uniform Size ◽  
Colloidal Spheres ◽  
Co Conversion

CeO2–MO x (M = Cu, Co, Ni) composite yolk–shell nanospheres with uniform size were fabricated by a general wet-chemical approach. It involved a non-equilibrium heat-treatment of Ce coordination polymer colloidal spheres (Ce-CPCSs) with a proper heating rate to produce CeO2 yolk–shell nanospheres, followed by a solvothermal treatment of as-synthesized CeO2 with M(CH3COO)2 in ethanol solution. During the solvothermal process, highly dispersed MO x species were decorated on the surface of CeO2 yolk–shell nanospheres to form CeO2–MO x composites. As a CO oxidation catalyst, the CeO2–MO x composite yolk–shell nanospheres showed strikingly higher catalytic activity than naked CeO2 due to the strong synergistic interaction at the interface sites between MO x and CeO2. Cycling tests demonstrate the good cycle stability of these yolk–shell nanospheres. The initial concentration of M(CH3COO)2·xH2O in the synthesis process played a significant role in catalytic performance for CO oxidation. Impressively, complete CO conversion as reached at a relatively low temperature of 145 °C over the CeO2–CuO x -2 sample. Furthermore, the CeO2–CuO x catalyst is more active than the CeO2–CoO x and CeO2–NiO catalysts, indicating that the catalytic activity is correlates with the metal oxide. Additionally, this versatile synthesis approach can be expected to create other ceria-based composite oxide systems with various structures for a broad range of technical applications.

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