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.

Mesostructured Pd/Mn3O4 catalyst for efficient low-temperature CO oxidation especially under moisture condition

RSC Advances ◽  
2014 ◽  
Vol 4 (67) ◽  
pp. 35762-35768 ◽  
Author(s):  
Gengnan Li ◽  
Liang Li ◽  
Yuan Yuan ◽  
Yinyin Yuan ◽  
Yongsheng Li ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Moisture Condition ◽  
Highly Dispersed ◽  
Low Temperature Co Oxidation

As-synthesized Pd/Mn3O4 catalysts possess relatively high surface area and highly dispersed palladium species and show much higher catalytic activity and stability for CO oxidation especially under wet conditions.

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.

Enhanced catalytic activity of Au-CeO2/Al2O3 monolith for low-temperature CO oxidation

2019 ◽  
Vol 129 ◽  
pp. 105729 ◽  
Author(s):  
Zhiwen Li ◽  
Huan Wang ◽  
Weiwei Zhao ◽  
Xin Xu ◽  
Quan Jin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Low Temperature Co Oxidation

scholarly journals {CeO2/Bi2Mo1−xRuxO6} and {Au/Bi2Mo1−xRuxO6} Catalysts for Low-Temperature CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 947 ◽  
Author(s):  
Edson Edain González ◽  
Ricardo Rangel ◽  
Javier Lara ◽  
Pascual Bartolo-Pérez ◽  
Juan José Alvarado-Gil ◽  
...  
Keyword(s):  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Supported Catalysts ◽  
Pollutant Emissions ◽  
Impregnation Method ◽  
Wet Impregnation ◽  
X Ray ◽  
Low Temperature Co Oxidation ◽  
Carbon Dioxide Co2 ◽  
Wet Impregnation Method

Nowadays, one of the most important challenges that humanity faces is to find alternative ways of reducing pollutant emissions. CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were prepared to efficiently transform carbon monoxide (CO) to carbon dioxide (CO2) at low temperatures. The systems were prepared in a two-step process. First, Bi2Mo1−xRuxO6 supports were synthesized through the hydrothermal procedure under microwave heating. Then, CeO2 was deposited on Bi2Mo1−xRuxO6 using the wet impregnation method, while the incipient impregnation method was selected to deposit gold nanoparticles. The CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were characterized using SEM microscopy and XRD. Furthermore, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used. Tests were carried out for the supported catalysts in CO oxidation, and high conversion values, nearing 100%, was observed in a temperature range of 100 to 250 °C. The results showed that the best system was the Au/Bi2Mo0.95Ru0.05O6 catalyst, with CO oxidation starting at 50 °C and reaching 100% conversion at 186 °C.

Low-temperature CO oxidation over CeO2 and CeO2@Co3O4 core–shell microspheres

2017 ◽  
Vol 41 (22) ◽  
pp. 13418-13424 ◽  
Author(s):  
Lu Zhang ◽  
Li Zhang ◽  
Guancheng Xu ◽  
Chi Zhang ◽  
Xin Li ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Core Shell ◽  
Synergistic Interactions ◽  
Low Temperature Co Oxidation

The excellent CO catalytic activity and stability of CeO2@Co3O4 composite were ascribed to the synergistic interactions between Co3O4 and CeO2.

scholarly journals Tailoring the reducibility and catalytic activity of CuO nanoparticles for low temperature CO oxidation

RSC Advances ◽  
2018 ◽  
Vol 8 (35) ◽  
pp. 19499-19511 ◽  
Author(s):  
Abdallah F. Zedan ◽  
Assem T. Mohamed ◽  
M. Samy El-Shall ◽  
Siham Y. AlQaradawi ◽  
Amina S. AlJaber
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Copper Oxide ◽  
Co Oxidation ◽  
Cuo Nanoparticles ◽  
Low Temperature Co Oxidation

Copper oxide (CuO) nanoparticles of tailored reducibility could be used as inexpensive, efficient and durable catalysts for CO oxidation at low temperature.

Pt NPs immobilized on a N-doped graphene@Al2O3 hybrid support as robust catalysts for low temperature CO oxidation

2018 ◽  
Vol 54 (79) ◽  
pp. 11168-11171 ◽  
Author(s):  
Zhimin Jia ◽  
Fei Huang ◽  
Jiangyong Diao ◽  
Jiayun Zhang ◽  
Jia Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Platinum Nanoparticles ◽  
Support Interaction ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Low Temperature Co Oxidation ◽  
Doped Graphene ◽  
Strong Metal Support Interaction

Platinum nanoparticles (Pt NPs) immobilized on a N-doped graphene@Al2O3 hybrid support (Al2O3@CNx) were synthesized and exhibit superior catalytic activity for low temperature CO oxidation, due to a strong metal–support interaction between Pt NPs and the N-doped.

scholarly journals Evolution of the pore and framework structure of NaY zeolite during alkali treatment and its effect on methanol oxidative carbonylation over a CuY catalyst

2020 ◽  
Vol 44 (11-12) ◽  
pp. 710-720
Author(s):  
Lifei Yan ◽  
Tingjun Fu ◽  
Jiajun Wang ◽  
Nilesh Narkhede ◽  
Zhong Li
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Dimethyl Carbonate ◽  
Alkali Treatment ◽  
Oxidative Carbonylation ◽  
Framework Structure ◽  
Y Zeolite ◽  
Cage Structure ◽  
X Ray

Alkali treatment is widely used on aluminosilicate zeolites with high Si/Al ratios in order to fabricate mesopores in the framework. However, for zeolites with low Si/Al ratios, the effect of alkali treatment on the pore and framework structure needed further study. In this work, Y zeolite is treated with NaOH solutions of different concentrations and is used as the support for Cu-based catalysts for oxidative carbonylation of methanol to dimethyl carbonate. The physicochemical properties of the supports and corresponding catalysts are characterized by N2 adsorption–desorption, X-ray diffraction, X-ray fluorescence, transmission electron microscopy, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, and H2-temperature-programmed reduction analyses. The results show that no obvious mesopores are formed under alkali treatment, even at high NaOH concentration. However, amorphous species present in the micropores of Y zeolite are removed, which increases the micropore surface area as well as the crystallinity. Simultaneously, the cage structure is partially destroyed, which also leads to a slight increase of the pore volume and surface area. The altered micropore structure eventually increases the content and accessibility of the exchanged Cu species, which is beneficial to the catalytic activity. When the concentration of NaOH is 0.6 M, the space time yield of dimethyl carbonate for the corresponding catalyst was 151.4 mg g−1 h−1 which is 3.3-fold higher than that of the untreated-Y-zeolite-supported Cu catalyst. However, further increasing the alkali treatment strength can seriously destroy the basic aluminosilicate structure of the Y zeolite and decrease its intrinsic ion-exchange capacity. This results in the formation of agglomerated CuO on the catalyst surface, which was not conducive to catalytic activity.

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).

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