Highly stable bimetallic Au–Cu supported on Al2O3 for selective CO oxidation in H2-rich gas: effects of Cu/Au atomic ratio and sensitive influence of particle size

RSC Advances ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 4899-4907 ◽  
Author(s):  
X. M. Liao ◽  
V. Caps ◽  
W. Chu ◽  
V. Pitchon

The effects of Au/Cu atomic ratio and thermal pretreatment on the catalytic performance of AuxCuy/Al2O3 for PROX were studied. The reduced AuxCuy/Al2O3 catalysts display higher catalytic activity and stability than the calcined catalysts.

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini

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.


2020 ◽  
Vol 10 (15) ◽  
pp. 5256-5266 ◽  
Author(s):  
Jihang Yu ◽  
Qiangsheng Guo ◽  
Xiuzhen Xiao ◽  
Haifang Mao ◽  
Dongsen Mao ◽  
...  

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.


2021 ◽  
Vol 21 (12) ◽  
pp. 6082-6087
Author(s):  
Chih-Wei Tang ◽  
Hsiang-Yu Shih ◽  
Ruei-Ci Wu ◽  
Chih-Chia Wang ◽  
Chen-Bin Wang

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.


2011 ◽  
Vol 287-290 ◽  
pp. 1704-1707
Author(s):  
Rong Bin Zhang ◽  
Liu Jing Yao ◽  
Yan Ju

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.


Author(s):  
Ke Ying Cai ◽  
Yu Sheng Liu ◽  
Ming Song ◽  
Ying Mei Zhou ◽  
Qing Liu ◽  
...  

<p>Iron oxyhydroxide was prepared by dropping ammonia water to Fe(NO<sub>3</sub>)<sub>3</sub>.9H<sub>2</sub>O dispersed in polyethylene glycol (PEG) 1000. The catalyst was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy and laser particle size analyzer. The results showed the catalyst modified with polyethylene glycol was amorphous. The addition of PEG during the preparation make the particle size of the catalyst was smaller and more uniform. The catalytic performance was tested in the reduction of nitroarenes to corresponding amines with hydrazine hydrate, and the catalyst showed excellent activity and stability. Copyright © 2016 BCREC GROUP. All rights reserved</p><p><em>Received: 2<sup>nd</sup> February 2016; Revised: 26<sup>th</sup> April 2016; Accepted: 7<sup>th</sup> June 2016</em></p><p><strong>How to Cite:</strong> Cai, K.Y., Liu, Y.S., Song, M., Zhou, Y.M., Liu, Q., Wang, X.H. (2016). Preparation of FeO(OH) Modified with Polyethylene Glycol and Its Catalytic Activity on the Reduction of Nitrobenzene with Hydrazine Hydrate. <em>Bulletin of Chemical Reaction Engineering &amp; Catalysis</em>, 11 (3): 363-368 (doi:10.9767/bcrec.11.3.576.363-368)</p><p><strong>Permalink/DOI:</strong> <a href="http://doi.org/10.9767/bcrec.11.3.576.363-368">http://doi.org/10.9767/bcrec.11.3.576.363-368</a></p>


Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2017
Author(s):  
Yuliya Gulyaeva ◽  
Maria Alekseeva (Bykova) ◽  
Olga Bulavchenko ◽  
Anna Kremneva ◽  
Andrey Saraev ◽  
...  

The heightened interest in liquid organic hydrogen carriers encourages the development of catalysts suitable for multicycle use. To ensure high catalytic activity and selectivity, the structure–reactivity relationship must be extensively investigated. In this study, high-loaded Ni–Cu catalysts were considered for the dehydrogenation of methylcyclohexane. The highest conversion of 85% and toluene selectivity of 70% were achieved at 325 °C in a fixed-bed reactor using a catalyst with a Cu/Ni atomic ratio of 0.23. To shed light on the relationship between the structural features and catalytic performance, the catalysts were thoroughly studied using a wide range of advanced physicochemical tools. The activity and selectivity of the proposed catalysts are related to the uniformity of Cu distribution and its interaction with Ni via the formation of metallic solid solutions. The method of introduction of copper in the catalyst plays a crucial role in the effectiveness of the interaction between the two metals.


Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1644
Author(s):  
Higareda ◽  
Kumar-Krishnan ◽  
García-Ruiz ◽  
Maya-Cornejo ◽  
Lopez-Miranda ◽  
...  

Bimetallic Au@Pt nanoparticles (NPs) with Pt monolayer shell are of much interest for applications in heterogeneous catalysts because of enhanced catalytic activity and very low Pt-utilization. However, precisely controlled synthesis with uniform Pt-monolayers and stability on the AuNPs seeds remain elusive. Herein, we report the controlled deposition of Pt-monolayer onto uniform AuNPs seeds to obtain Au@Pt core–shell NPs and their Pt-coverage dependent electrocatalytic activity for methanol electro-oxidation. The atomic ratio between Au/Pt was effectively tuned by varying the precursor solution ratio in the reaction solution. The morphology and atomic structure of the Au@Pt NPs were analyzed by high-resolution scanning transmission electron microcopy (HR-STEM) and X-ray diffraction (XRD) techniques. The results demonstrated that the Au@Pt core–shell NPs with Pt-shell thickness (atomic ratio 1:2) exhibit higher electrocatalytic activity for methanol electro-oxidation reaction, whereas higher and lower Pt ratios showed less overall catalytic performance. Such higher catalytic performance of Au@Pt NPs (1:2) can be attributed to the weakened CO binding on the Pt/monolayers surface. Our present synthesis strategy and optimization of the catalytic activity of Au@Pt core–shell NPs catalysts provide promising approach to rationally design highly active catalysts with less Pt-usage for high performance electrocatalysts for applications in fuel cells.


Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6413
Author(s):  
Pierre-Alexis Répécaud ◽  
Monica Ceretti ◽  
Mimoun Aouine ◽  
Céline Delwaulle ◽  
Emmanuel Nonnet ◽  
...  

The support material can play an important role in oxidation catalysis, notably for CO oxidation. Here, we study two materials of the Brownmillerite family, CaFeO2.5 and SrFeO2.5, as one example of a stoichiometric phase (CaFeO2.5, CFO) and one existing in different modifications (SrFeO2.75, SrFeO2.875 and SrFeO3, SFO). The two materials are synthesized using two synthesis methods, one bottom-up approach via a complexation route and one top-down method (electric arc fusion), allowing to study the impact of the specific surface area on the oxygen mobility and catalytic performance. CO oxidation on 18O-exchanged materials shows that oxygen from SFO participates in the reaction as soon as the reaction starts, while for CFO, this onset takes place 185 °C after reaction onset. This indicates that the structure of the support material has an impact on the catalytic performance. We report here on significant differences in the catalytic activity linked to long-term stability of CFO and SFO, which is an important parameter not only for possible applications, but equally to better understand the mechanism of the catalytic activity itself.


2015 ◽  
Vol 3 (2) ◽  
pp. 54-64
Author(s):  
Larisa Lutsenko ◽  
Ludmila Oleksenko ◽  
German Telbiz ◽  
Victoriia Gerasova

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


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