Effect of Templates on Catalytic Activity of Ordered Mesoporous Ceria for CO Oxidation

2014 ◽  
Vol 1033-1034 ◽  
pp. 95-98
Author(s):  
Peng Yang ◽  
Shi Yu Zhou ◽  
Jia Heng Lei
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Mesoporous Carbon ◽  
Catalytic Properties ◽  
X Ray ◽  
Catalytic Activities ◽  
Ordered Mesoporous ◽  
Ceria Catalysts ◽  
Fluorescence Spectrometer ◽  
The Relationship

Mesoporous ceria catalysts were prepared by nanocasting of a mesoporous carbon and KIT-6. The prepared mesoporous ceria catalysts were used to catalyze CO oxidation. The various characterization techniques were employed to study the relationship between catalyst nature and catalytic properties. The results indicate that ceria prepared by using mesoporous carbon as template possess an ordered mesoporous architecture and exhibit much better catalytic activity compared with those prepared by using KIT-6 as template. The residual SiO2from KIT-6 was demonstrated to be the main reason for the much worse catalytic activities by the characterization results of X-ray Fluorescence Spectrometer and FTIR spectra.

Controllable synthesis of Ni nanotube arrays and their structure-dependent catalytic activity toward dye degradation

CrystEngComm ◽  
2014 ◽  
Vol 16 (21) ◽  
pp. 4406-4413 ◽  
Author(s):  
Xiang-Zi Li ◽  
Kong-Lin Wu ◽  
Yin Ye ◽  
Xian-Wen Wei
Keyword(s):  
Catalytic Activity ◽  
Catalytic Properties ◽  
Dye Degradation ◽  
Nanotube Arrays ◽  
Nanorod Arrays ◽  
Growth Mechanisms ◽  
Controllable Synthesis ◽  
Catalytic Activities ◽  
One Step ◽  
The Relationship

Ni nanotube (nanorod) arrays are controllably fabricated by a one-step approach, the GDDATG and DDCG growth mechanisms are introduced. The Ni nanostructures present higher catalytic activities for dye degradation, the relationship between structures and catalytic properties is also studied.

A Label-Free Electrochemical Aptasensor for the Rapid Detection of Tetracycline Based on Ordered Mesoporous Carbon–Fe3O4

2018 ◽  
Vol 71 (3) ◽  
pp. 170 ◽  
Author(s):  
Xuejia Zhan ◽  
Guangzhi Hu ◽  
Thomas Wagberg ◽  
Dongwei Zhang ◽  
Pei Zhou
Keyword(s):  
Photoelectron Spectroscopy ◽  
Mesoporous Carbon ◽  
Physical Adsorption ◽  
Differential Pulse ◽  
Ordered Mesoporous Carbon ◽  
Label Free ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ordered Mesoporous ◽  
Modification Procedure

A novel aptasensor based on a tetracycline (TET) aptamer immobilized by physical adsorption on an ordered mesoporous carbon–Fe3O4 (OMC-Fe3O4)-modified screen-printed electrode surface was successfully fabricated. OMC-Fe3O4 was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The modification procedure of the aptasensor was characterized by cyclic voltammetry. Interaction between the TET aptamer and target was determined by differential pulse voltammetry. Under optimal conditions, the proposed aptasensor exhibited good electrochemical sensitivity to TET in a concentration range of 5 nM to 10 μM, with a detection limit of 0.8 nM (S/N = 3). This aptasensor exhibited satisfactory specificity, reproducibility, and stability.

scholarly journals CO Oxidation over Metal Oxide (La2O3, Fe2O3, PrO2, Sm2O3, and MnO2) Doped CuO-Based Catalysts Supported on Mesoporous Ce0.8Zr0.2O2 with Intensified Low-Temperature Activity

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 724 ◽  
Author(s):  
Yan Cui ◽  
Leilei Xu ◽  
Mindong Chen ◽  
Chufei Lv ◽  
Xinbo Lian ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Co Oxidation ◽  
Active Sites ◽  
Earth Metal ◽  
High Dispersion ◽  
Impregnation Method ◽  
X Ray

CuO-based catalysts are usually used for CO oxidation owing to their low cost and excellent catalytic activities. In this study, a series of metal oxide (La2O3, Fe2O3, PrO2, Sm2O3, and MnO2)-doped CuO-based catalysts with mesoporous Ce0.8Zr0.2O2 support were simply prepared by the incipient impregnation method and used directly as catalysts for CO catalytic oxidation. These mesoporous catalysts were systematically characterized by X-ray powder diffraction (XRD), N2 physisorption, transmission electron microscopy (TEM), energy-dispersed spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS), and H2 temperature programmed reduction (H2-TPR). It was found that the CuO and the dopants were highly dispersed among the mesoporous framework via the incipient impregnation method, and the strong metal framework interaction had been formed. The effects of the types of the dopants and the loading amounts of the dopants on the low-temperature catalytic performances were carefully studied. It was concluded that doped transition metal oxides could regulate the oxygen mobility and reduction ability of catalysts, further improving the catalytic activity. It was also found that the high dispersion of rare earth metal oxides (PrO2, Sm2O3) was able to prevent the thermal sintering and aggregation of CuO-based catalysts during the process of calcination. In addition, their presence also evidently improved the reducibility and significantly reduced the particle size of the CuO active sites for CO oxidation. The results demonstrated that the 15CuO-3Fe2O3/M-Ce80Zr20 catalyst with 3 wt. % of Fe2O3 showed the best low-temperature catalytic activity toward CO oxidation. Overall, the present Fe2O3-doped CuO-based catalysts with mesoporous nanocrystalline Ce0.8Zr0.2O2 solid solution as support were considered a promising series of catalysts for low-temperature CO oxidation.

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.

scholarly journals Aerobic Oxidation of 5-Hydroxymethylfurfural over Ag Nanoparticle Catalysts Stabilized by Polyvinylpyrrolidone with Different Molecular Weights

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1624
Author(s):  
Haian Xia ◽  
Jiahuan An ◽  
Weizi Zhang
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Catalytic Properties ◽  
Aerobic Oxidation ◽  
Ag Nps ◽  
Oxidation Activity ◽  
X Ray ◽  
Remarkable Effect ◽  
Molecular Weights ◽  
Metal Support Interaction

The metal–support interaction (MSI) has a remarkable effect on the catalytic properties, but how to precisely modulate its degree remains a huge challenge. Herein, polyvinylpyrrolidone (PVP) with three different molecular weights (MWs) (24, 58, and 130 kDa) was used as a capping agent to fabricate Ag nanoparticles (NPs) supported on ZrO2. The physiochemical properties of the catalysts were characterized by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier transform infrared (FT-IR) techniques. The impacts of MSI on the catalytic activity and reaction kinetics for aerobic oxidation of 5-hydroxymethylfurfural (HMF) were investigated. The results showed that the introduction of PVP with various MWs could efficiently tailor the interfacial interactions and charge transfers (CT) among PVP, the support, and Ag NPs, thereby affecting the oxidation activity of HMF. The turnover number (TON) for HMF oxidation decreases in the order of unsupported colloidal Ag clusters > Ag/ZrO2 (58,000) > Ag/ZrO2 (130,000) > Ag/ZrO2 (24,000) > Ag/ZrO2. The reason for this large difference in the catalytic activity for HMF oxidation is that various MWs of PVP result in a change of MSI, thereby facilitating CT from PVP to Ag metal sites. This study offers a new strategy for modulating MSI by varying the MW of capping agents, thereby tuning the catalytic properties in the oxidation of HMF.

scholarly journals The Sintering of Au Nanoparticles on Flat {100}, {111} and Zigzagged {111}-Nanofacetted Structures of Ceria and Its Influence on Catalytic Activity in CO Oxidation and CO PROX

2020 ◽  
Author(s):  
O. S. Bezkrovnyi ◽  
P. Kraszkiewicz ◽  
W. Mista ◽  
L. Kepinski
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Catalytic Activity ◽  
Beneficial Effect ◽  
Co Oxidation ◽  
Au Nanoparticles ◽  
Ceria Support ◽  
Ceria Catalysts ◽  
Thermal Stability Of

Abstract The thermal stability of Au nanoparticles on ceria support of various morphology (nanocubes, nanooctahedra, and {111}-nanofacetted nanocubes) in oxidizing and reducing atmospheres was investigated by electron microscopy. A beneficial effect of the reconstruction of edges of ceria nanocubes into zigzagged {111}-nanofacetted structures on the inhibition of sintering of Au nanoparticles was shown. The influence of different morphology of Au particles on various ceria supports on the reducibility and catalytic activity in CO oxidation, and CO PROX of Au/ceria catalysts was also investigated and discussed. It was shown, that ceria nanocubes with flat {110} terminated edges are more suitable as a support for Au nanoparticles, used to catalyze CO oxidation, than zigzagged {111}- nanofacetted structures. Graphic Abstract

scholarly journals Ambient Temperature CO Oxidation Using Palladium–Platinum Bimetallic Catalysts Supported on Tin Oxide/Alumina

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1223
Author(s):  
James K. Aldridge ◽  
Louise R. Smith ◽  
David J. Morgan ◽  
Albert F. Carley ◽  
Mandy Humphreys ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Ambient Temperature ◽  
Co Oxidation ◽  
Tin Oxide ◽  
Photoelectron Spectroscopy ◽  
Bimetallic Catalysts ◽  
Moisture Resistance ◽  
X Ray ◽  
Sodium Stannate ◽  
Palladium Platinum

A series of Pt-based catalysts were synthesised and investigated for ambient temperature CO oxidation with the aim to increase catalytic activity and improve moisture resistance through support modification. Initially, bimetallic PtPd catalysts supported on alumina were found to exhibit superior catalytic activity compared with their monometallic counterparts for the reaction. Following an investigation into the effect of Pt/Pd ratio, a composition of 0.1% Pt/0.4% Pd was selected for further studies. Following this, SnO2/Al2O3 supports were synthesised from a variety of tin oxide sources. Catalytic activity was improved using sodium stannate and tin oxalate precursors compared with a traditional tin oxide slurry. Catalytic activity versus tin concentration was found to vary significantly across the three precursors, which was subsequently investigated by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX).

scholarly journals Catalytic activity of nanostructured Au: Scale effects versus bimetallic/bifunctional effects in low-temperature CO oxidation on nanoporous Au

2013 ◽  
Vol 4 ◽  
pp. 111-128 ◽  
Author(s):  
Lu-Cun Wang ◽  
Yi Zhong ◽  
Haijun Jin ◽  
Daniel Widmann ◽  
Jörg Weissmüller ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Scale Effects ◽  
Structural Parameters ◽  
Kinetic Measurements ◽  
X Ray ◽  
Low Temperature Co Oxidation

The catalytic properties of nanostructured Au and their physical origin were investigated by using the low-temperature CO oxidation as a test reaction. In order to distinguish between structural effects (structure–activity correlations) and bimetallic/bifunctional effects, unsupported nanoporous gold (NPG) samples prepared from different Au alloys (AuAg, AuCu) by selective leaching of a less noble metal (Ag, Cu) were employed, whose structure (surface area, ligament size) as well as their residual amount of the second metal were systematically varied by applying different potentials for dealloying. The structural and chemical properties before and after 1000 min reaction were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic behavior was evaluated by kinetic measurements in a conventional microreactor and by dynamic measurements in a temporal analysis of products (TAP) reactor. The data reveal a clear influence of the surface contents of residual Ag and Cu species on both O2 activation and catalytic activity, while correlations between activity and structural parameters such as surface area or ligament/crystallite size are less evident. Consequences for the mechanistic understanding and the role of the nanostructure in these NPG catalysts are discussed.

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