Nanostructured Fe-Co Catalysts Generated by Ultrasound

1994 ◽  
Vol 351 ◽  
Author(s):  
Kenneth S. Suslick ◽  
Mingming Fang ◽  
Taeghwan Hyeon ◽  
Andrzej A. Cichowlas
Keyword(s):  
Catalytic Activity ◽  
High Surface ◽  
Pure Metal ◽  
High Catalytic Activity ◽  
Small Surface ◽  
Co Catalysts ◽  
Surface Areas ◽  
Alloy Particles ◽  
Dehydrogenation Of Cyclohexane ◽  
Co Alloys

ABSTRACTBimetallic catalysts have been studied intensively because of their unique activity and selectivity. Unsupported alloy catalysts, however, are usually of limited value due to their very small surface areas. We have now developed a sonochemical synthesis of bimetallic alloys that provides both high surface areas and high catalytic activity. We have produced Fe-Co alloys by ultrasonic irradiation of mixed solutions of Fe(CO)5 and Co(CO)3(NO) in hydrocarbon solvents. The alloy composition can be controlled simply by changing the ratio of precursor concentrations. After treatment at 673K under H2 flow for 2 hours, we obtain nearly pure alloys. BET results show that the surface areas of these alloys are large (10-30 m2/g). TEM and SEM show that the alloy particles are porous agglomerates of particles with diameters of 10-20 nm. Sonochemically prepared Fe, Co, and Fe-Co powders have very high catalytic activity for dehydrogenation and hydrogenolysis of cyclohexane. Furthermore, sonochemically prepared Fe-Co alloys show high catalytic selectivity for dehydrogenation of cyclohexane to benzene; the 1:1 ratio alloy has much higher selectivity for dehydrogenation over hydrogenolysis than either pure metal.

scholarly journals Flower-Shaped C-Dots/Co3O4{111} Constructed with Dual-Reaction Centers for Enhancement of Fenton-Like Reaction Activity and Peroxymonosulfate Conversion to Sulfate Radical

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 135
Author(s):  
Zhibin Wen ◽  
Qianqian Zhu ◽  
Jiali Zhou ◽  
Shudi Zhao ◽  
Jinnan Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Site ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Centers ◽  
Organic Radicals ◽  
The Other ◽  
High Catalytic Activity ◽  
High Adsorption ◽  
High Turnover

Novel flower-shaped C-dots/Co3O4{111} with dual-reaction centers were constructed to improve the Fenton-like reaction activity and peroxymonosulfate (PMS) conversion to sulfate radicals. Due to the exposure of a high surface area and Co3O4{111} facets, flower-shaped C-dots/Co3O4{111} could provide more Co(II) for PMS activation than traditional spherical Co3O4{110}. Meanwhile, PMS was preferred for adsorption on Co3O4{111} facets because of a high adsorption energy and thereby facilitated the electron transfer from Co(II) to PMS. More importantly, the Co–O–C linkage between C-dots and Co3O4{111} induced the formation of the dual-reaction center, which promoted the production of reactive organic radicals (R•). PMS could be directly reduced to SO4−• by R• over C-dots. On the other hand, electron transferred from R• to Co via Co–O–C linkage could accelerate the redox of Co(II)/(III), avoiding the invalid decomposition of PMS. Thus, C-dots doped on Co3O4{111} improved the PMS conversion rate to SO4−• over the single active site, resulting in high turnover numbers (TONs). In addition, TPR analysis indicated that the optimal content of C-dots doped on Co3O4{111} is 2.5%. More than 99% of antibiotics and dyes were degraded over C-dots/Co3O4{111} within 10 min. Even after six cycles, C-dots/Co3O4{111} still remained a high catalytic activity.

Cascade catalysis of highly active bimetallic Au/Pd nanoclusters: structure–function relationship investigation using anomalous small-angle X-ray scattering and UV–Vis spectroscopy

2013 ◽  
Vol 46 (5) ◽  
pp. 1353-1360 ◽  
Author(s):  
Sylvio Haas ◽  
Robert Fenger ◽  
Edoardo Fertitta ◽  
Klaus Rademann
Keyword(s):  
Catalytic Activity ◽  
Structural Characteristics ◽  
High Surface ◽  
Volume Ratio ◽  
Single Type ◽  
High Catalytic Activity ◽  
Highly Active ◽  
Bimetallic Nanoclusters ◽  
Vis Spectroscopy ◽  
Cascade Catalysis

Recently, a so-called `crown-jewel' concept of preparation of Au/Pd-based colloidal nanoclusters has been reported [Zhang, Watanabe, Okumura, Haruta & Toshima (2011).Nat. Mater.11, 49–52]. Here, a different way of preparing highly active Au/Pd-based nanoclusters is presented. The origin of the increased activity of Au/Pd-based colloidal bimetallic nanoclusters was unclear up to now. However, it is, in general, accepted that in the nanometre range (1–100 nm) the cluster size, shape and composition affect the structural characteristics (e.g.lattice symmetry, unit cell), electronic properties (e.g.band gap) and chemical properties (e.g.catalytic activity) of a material. Hence, a detailed study of the relationship between the nanostructure of nanoclusters and their catalytic activity is presented here. The results indicate that a high surface-to-volume ratio of the nanoclusters combined with the presence of `both' Au and Pd isolated regions at the surface are crucial to achieve a high catalytic activity. A detailed structure elucidation directly leads to a mechanistic proposal, which indeed explains the higher catalytic activity of Au/Pd-based catalysts compared with pure metallic Au or Pd. The mechanism is based on cascade catalysis induced by a single type of nanoparticle with an intermixed surface of Au and Pd.

High surface area, high catalytic activity titanium dioxide aerogels prepared by solvothermal crystallization

2020 ◽  
Vol 47 ◽  
pp. 223-230 ◽  
Author(s):  
Xian Yue ◽  
Junhui Xiang ◽  
Junyong Chen ◽  
Huaxin Li ◽  
Yunsheng Qiu ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Catalytic Activity ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
High Catalytic Activity

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.

scholarly journals Highly effective photocatalytic performance of {001}-TiO2/MoS2/RGO hybrid heterostructures for the reduction of Rh B

RSC Advances ◽  
2019 ◽  
Vol 9 (26) ◽  
pp. 15033-15041 ◽  
Author(s):  
Ya Gao ◽  
Yongjie Zheng ◽  
Jixing Chai ◽  
Jingzhi Tian ◽  
Tao Jing ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Photocatalytic Performance ◽  
Photogenerated Electron ◽  
High Catalytic Activity ◽  
Electron Hole ◽  
Co Catalysts ◽  
Effective Separation ◽  
Key Features ◽  
Rapid Transfer ◽  
Photocatalytic Materials

Effective separation and rapid transfer of photogenerated electron–hole pairs are key features of photocatalytic materials with high catalytic activity, which could be achieved by co-catalysts.

N-doped carbon nanocages with high catalytic activity and durability for oxygen reduction

2015 ◽  
Vol 3 (23) ◽  
pp. 12427-12435 ◽  
Author(s):  
Xiao Xia Wang ◽  
Biao Zou ◽  
Xin Xin Du ◽  
Jian Nong Wang
Keyword(s):  
Catalytic Activity ◽  
Oxygen Reduction Reaction ◽  
Specific Surface ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
High Catalytic Activity ◽  
Surface Areas ◽  
Excellent Activity ◽  
Specific Surface Areas

N-doped carbon nanocages with high specific surface areas exhibited excellent activity and durability for oxygen reduction reaction in acidic electrolytes.

High-surface-area activated red mud supported Co3O4 catalysts for efficient catalytic oxidation of CO

RSC Advances ◽  
2016 ◽  
Vol 6 (97) ◽  
pp. 94748-94755 ◽  
Author(s):  
Zhong-Pan Hu ◽  
Hui Zhao ◽  
Ze-Min Gao ◽  
Zhong-Yong Yuan
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Co Oxidation ◽  
Red Mud ◽  
High Surface ◽  
High Surface Area ◽  
High Catalytic Activity ◽  
Oxidation Of Co ◽  
Catalytic Oxidation Of Co ◽  
Low Temperature Co Oxidation

Red mud is activated and employed as the support of Co3O4 catalysts, exhibiting high catalytic activity for low-temperature CO oxidation.

scholarly journals Furfural Hydrogenation on Modified Niobia

2019 ◽  
Vol 9 (11) ◽  
pp. 2287 ◽  
Author(s):  
Andrea Jouve ◽  
Stefano Cattaneo ◽  
Daniel Delgado ◽  
Nicola Scotti ◽  
Claudio Evangelisti ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Furfuryl Alcohol ◽  
Surface Acidity ◽  
High Surface ◽  
Pt Nanoparticles ◽  
Acid Sites ◽  
High Catalytic Activity ◽  
Lewis Acid Sites ◽  
Furfural Hydrogenation

In this study, niobia-based materials have been used as supports for Pt nanoparticles and used in the hydrogenation of furfural. The incorporation of dopants (W6+ and Ti4+) in the Nb2O5 structure induced modifications in the surface acidity of the support; in particular, the addition of W6+ increased the amount of Lewis acid sites, while the addition of Ti4+ decreased the number of Lewis acid sites. As a result, the catalytic activity towards the hydrogenation of furfural was affected; high surface acidity resulted in high catalytic activity. The selectivity of the reaction changed with the support acidity as well, with higher amount of furfuryl alcohol produced decreasing the Lewis acid sites.

Highly Ordered Mesoporous WO3 with Excellent Catalytic Performance and Reusability for Deep Oxidative Desulfurization

NANO ◽  
2015 ◽  
Vol 10 (05) ◽  
pp. 1550075 ◽  
Author(s):  
Zhenghua Li ◽  
Heon Jong Jeong ◽  
Kumarsrinivasan Sivaranjani ◽  
Byung Jin Song ◽  
Su Bin Park ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Oxidative Desulfurization ◽  
High Catalytic Activity ◽  
Ordered Mesoporous ◽  
Model Oil ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

Highly ordered mesoporous tungsten trioxide ( WO 3) with high surface area (75 m2/g) and well-defined mesopores were successfully prepared through a hard templating method using a mesoporous silica KIT-6 as a template and ( NH 4)6 H 2 W 12 O 40 ⋅ x H 2 O as a tungsten precursor. Oxidative desulfurization of a model oil with H 2 O 2 as the oxidant was carried out at 50°C under atmospheric pressure in order to analyze the catalytic activity. The desulfurization reactions were optimized by various kinds of reaction parameters such as H 2 O 2/ S molar ratio, reaction temperatures and series of sulfur-containing compounds [dibenzothiophene (DBT), benzothiophene (BT) and 4,6-dimethyl dibenzothiophene (4,6-DMBT)]. Excellent catalytic activity for the removal of the sulfur-containing compounds from the model oil was observed with mesoporous WO 3 catalyst, where the activity was maintained during 5 recycle tests without any regeneration process. The high catalytic activity and durability is mainly attributed to well-defined mesopores and high surface area of mesoporous WO 3 catalyst.

scholarly journals Enhanced Activity for CO Preferential Oxidation over CuO Catalysts Supported on Nanosized CeO2 with High Surface Area and Defects

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 884
Author(s):  
Lei Gong ◽  
Weiwei Jie ◽  
Yumeng Liu ◽  
Xinchen Lin ◽  
Wenyong Deng ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Oxygen Vacancies ◽  
High Surface ◽  
High Surface Area ◽  
High Catalytic Activity ◽  
Preferential Oxidation ◽  
Preferential Oxidation Of Co ◽  
Co Preferential Oxidation ◽  
Strength Of Interaction

Nanosizedceria (n-CeO2) was synthesized by a facile method in 2-methylimidazolesolution. The characterization results of XRD, N2 adsorption-desorption, Raman and TEM indicate that n-CeO2 shows a regular size of 10 ± 1 nm, a high surface area of 130 m2·g−1 and oxygen vacancies on the surface. A series of CuO/n-CeO2 catalysts (CuCeOX) with different copper loading were prepared for the preferential oxidation of CO in H2-rich gases (CO-PROX). All CuCeOX catalysts exhibit a high catalytic activity due to the excellent structural properties of n-CeO2, over which the 100% conversion of CO is obtained at 120 °C. The catalytic activity of CuCeOX catalysts increases in the order of CuCeO12 < CuCeO3 < CuCeO6 < CuCeO9. It is in good agreement with the order of the amount of active Cu+ species, Ce3+ species and oxygen vacancies on these catalysts, suggesting that the strength of interaction between highly dispersed CuO species and n-CeO2 is the decisive factor for the activity. The stronger interaction results in the formation of more readily reducible copper species on CuCeO9, which shows the highest activity with high stability and the broadest temperature “window” for complete CO conversion (120–180 °C).

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