scholarly journals Cu42Ge24Na4—A Giant Trimetallic Sesquioxane Cage: Synthesis, Structure, and Catalytic Activity

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 484 ◽  
Author(s):  
Alena Kulakova ◽  
Alexey Bilyachenko ◽  
Victor Khrustalev ◽  
Yan Zubavichus ◽  
Pavel Dorovatovskii ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Nitric Acid ◽  
Hydroxyl Radicals ◽  
Cost Effective ◽  
Catalyst Loading ◽  
High Catalytic Activity ◽  
Initial Concentration ◽  
Alkyl Hydroperoxides ◽  
Tert Butyl Hydroperoxide ◽  
Oxidative Amidation

Unprecedented germanium-based sesquioxane exhibits an extremely high nuclearity (Cu42Ge24Na4) and unusual encapsulation features. The compound demonstrated a high catalytic activity in the oxidative amidation of alcohols, with cost-effective catalyst loading down to 400 ppm of copper, and in the oxidation of cyclohexane and other alkanes with H2O2 in acetonitrile in the presence of nitric acid. Selectivity parameters and the mode of dependence of initial cyclohexane oxidation rate on initial concentration of the hydrocarbon indicate that the reaction occurs with the participation of hydroxyl radicals and alkyl hydroperoxides are formed as the main primary product. Alcohols have been transformed into the corresponding ketones by the catalytic oxidation with tert-butyl hydroperoxide.

scholarly journals High Catalytic Activity of Heterometallic (Fe6Na7 and Fe6Na6) Cage Silsesquioxanes in Oxidations with Peroxides

2017 ◽  
Author(s):  
Alexey I. Yalymov ◽  
Alexey N. Bilyachenko ◽  
Mikhail M. Levitsky ◽  
Alexander A. Korlyukov ◽  
Victor N. Khrustalev ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Hydroxyl Radicals ◽  
Acetonitrile Solution ◽  
High Catalytic Activity ◽  
X Ray ◽  
Complex Ii ◽  
Alkyl Hydroperoxides ◽  
Catalytically Active ◽  
Very High

Two types of heterometallic (Fe(III),Na) silsesquioxanes [Ph5Si5O10]2[Ph10Si10O21]Fe6(O2‒)2Na7(H3O+)(MeOH)2(MeCN)4.5.1.25(MeCN), I, and [Ph5Si5O10]2[Ph4Si4O8]2Fe6Na6(O2‒)3(MeCN)8.5(H2O)8.44, II, were obtained and characterized. X-Ray studies established distinctive structures of both products, with pair of Fe(III)-O-based triangles surrounded by siloxanolate ligands, giving fascinating cage architectures. Complex II proved to be catalytically active in the formation of amides from alcohols and amines, thus becoming a rare example of metallasilsesquioxanes performing homogeneous catalysis. Benzene, cyclohexane and other alkanes, as well as alcohols, can be oxidized in acetonitrile solution to phenol, the corresponding alkyl hydroperoxides and ketones, respectively, by hydrogen peroxide in air in the presence of catalytic amounts of complex II and trifluoroacetic acid. Thus, the cyclohexane oxidation at 20 °C gave oxygenates in very high for alkanes yield (48% based on alkane). The kinetic behaviour of the system indicates that the mechanism includes the formation of hydroxyl radicals generated from hydrogen peroxide in its interaction with diiron species. The latter are formed via monomerization of starting hexairon complex with further dimerization of the monomers.

A Cost-Effective 3D Hydrogen Evolution Cathode with High Catalytic Activity: FeP Nanowire Array as the Active Phase

2014 ◽  
Vol 53 (47) ◽  
pp. 12855-12859 ◽  
Author(s):  
Ping Jiang ◽  
Qian Liu ◽  
Yanhui Liang ◽  
Jingqi Tian ◽  
Abdullah M. Asiri ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Nanowire Array ◽  
Cost Effective ◽  
Active Phase ◽  
High Catalytic Activity

Pyrite cinder as a cost-effective heterogeneous catalyst in heterogeneous Fenton reaction: decomposition of H2O2 and degradation of Acid Red B

2014 ◽  
Vol 70 (9) ◽  
pp. 1548-1554 ◽  
Author(s):  
Deli Wu ◽  
Yanxia Liu ◽  
Dong Duan ◽  
Luming Ma
Keyword(s):  
Catalytic Activity ◽  
Metal Ions ◽  
Cost Effective ◽  
High Catalytic Activity ◽  
Order Kinetic ◽  
Pyrite Cinder ◽  
Heterogeneous Fenton ◽  
Kinetic Rate Constant ◽  
Heterogeneous Fenton Reaction ◽  
Decomposition Of H2o2

Pyrite cinder (PyC) was employed as a heterogeneous Fenton-like catalyst, and its catalytic activity was evaluated in view of the effects of catalyst dosage, pH and leaching metal ions. PyC showed significant reactivity, and the pseudo-first-order kinetic rate constant for decomposition of H2O2 and degradation of Acid Red B (ARB) were 3.4 and 14.89 (10−3 min−1) respectively when pH = 5. When 20 g/L PyC was added into 10 mM H2O2 solution in neutral pH, H2O2 could be completely degraded within 4 h, and more than 90% ARB was removed. Leaching metal ions from PyC were found to have little effect on decomposition of H2O2 or on degradation of ARB. PyC still had high catalytic activity after five successive runs. The decomposition mechanism of H2O2 was analyzed and the Haber–Weiss mechanism was employed in this paper. The electron spin resonance image showed •OH was produced and increased between 3 and 5 min in the PyC catalyzing H2O2 reaction, which demonstrated that PyC had a durable ability to produce •OH.

scholarly journals Novel Oxidovanadium Complexes with Redox-Active R-Mian and R-Bian Ligands: Synthesis, Structure, Redox and Catalytic Properties

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5706
Author(s):  
Anton N. Lukoyanov ◽  
Iakov S. Fomenko ◽  
Marko I. Gongola ◽  
Lidia S. Shul’pina ◽  
Nikolay S. Ikonnikov ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Dft Calculations ◽  
Oh Radicals ◽  
High Catalytic Activity ◽  
Alternative Mechanism ◽  
Alkyl Hydroperoxides ◽  
Redox Active ◽  
Diimine Ligand ◽  
Active Nature ◽  
The Difference

A new monoiminoacenaphthenone 3,5-(CF3)2C6H3-mian (complex 2) was synthesized and further exploited, along with the already known monoiminoacenaphthenone dpp-mian, to obtain oxidovanadium(IV) complexes [VOCl2(dpp-mian)(CH3CN)] (3) and [VOCl(3,5-(CF3)2C6H3-bian)(H2O)][VOCl3(3,5-(CF3)2C6H3-bian)]·2.85DME (4) from [VOCl2(CH3CN)2(H2O)] (1) or [VCl3(THF)3]. The structure of all compounds was determined using X-ray structural analysis. The vanadium atom in these structures has an octahedral coordination environment. Complex 4 has an unexpected structure. Firstly, it contains 3,5-(CF3)2C6H3-bian instead of 3,5-(CF3)2C6H3-mian. Secondly, it has a binuclear structure, in contrast to 3, in which two oxovanadium parts are linked to each other through V=O···V interaction. This interaction is non-covalent in origin, according to DFT calculations. In structures 2 and 3, non-covalent π-π staking interactions between acenaphthene moieties of the neighboring molecules (distances are 3.36–3.40 Å) with an estimated energy of 3 kcal/mol were also found. The redox properties of the obtained compounds were studied using cyclic voltammetry in solution. In all cases, the reduction processes initiated by the redox-active nature of the mian or bian ligand were identified. The paramagnetic nature of complexes 3 and 4 has been proven by EPR spectroscopy. Complexes 3 and 4 exhibited high catalytic activity in the oxidation of alkanes and alcohols with peroxides. The yields of products of cyclohexane oxidation were 43% (complex 3) and 27% (complex 4). Based on the data regarding the study of regio- and bond-selectivity, it was concluded that hydroxyl radicals play the most crucial role in the reaction. The initial products in the reactions with alkanes are alkyl hydroperoxides, which are easily reduced to their corresponding alcohols by the action of triphenylphosphine (PPh3). According to the DFT calculations, the difference in the catalytic activity of 3 and 4 is most likely associated with a different mechanism for the generation of ●OH radicals. For complex 4 with electron-withdrawing CF3 substituents at the diimine ligand, an alternative mechanism, different from Fenton’s and involving a redox-active ligand, is assumed.

scholarly journals Metal Complexes Containing Redox-Active Ligands in Oxidation of Hydrocarbons and Alcohols: A Review

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1046 ◽  
Author(s):  
Georgiy B. Shul’pin ◽  
Yuriy N. Kozlov ◽  
Lidia S. Shul’pina
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Oxidation States ◽  
Acetonitrile Molecule ◽  
Oxidation Of Hydrocarbons ◽  
Alkyl Hydroperoxides ◽  
Redox Active ◽  
Tert Butyl Hydroperoxide ◽  
Saturated And Aromatic Hydrocarbons

Ligands are innocent when they allow oxidation states of the central atoms to be defined. A noninnocent (or redox) ligand is a ligand in a metal complex where the oxidation state is not clear. Dioxygen can be a noninnocent species, since it exists in two oxidation states, i.e., superoxide (O2−) and peroxide (O22−). This review is devoted to oxidations of C–H compounds (saturated and aromatic hydrocarbons) and alcohols with peroxides (hydrogen peroxide, tert-butyl hydroperoxide) catalyzed by complexes of transition and nontransition metals containing innocent and noninnocent ligands. In many cases, the oxidation is induced by hydroxyl radicals. The mechanisms of the formation of hydroxyl radicals from H2O2 under the action of transition (iron, copper, vanadium, rhenium, etc.) and nontransition (aluminum, gallium, bismuth, etc.) metal ions are discussed. It has been demonstrated that the participation of the second hydrogen peroxide molecule leads to the rapture of O–O bond, and, as a result, to the facilitation of hydroxyl radical generation. The oxidation of alkanes induced by hydroxyl radicals leads to the formation of relatively unstable alkyl hydroperoxides. The data on regioselectivity in alkane oxidation allowed us to identify an oxidizing species generated in the decomposition of hydrogen peroxide: (hydroxyl radical or another species). The values of the ratio-of-rate constants of the interaction between an oxidizing species and solvent acetonitrile or alkane gives either the kinetic support for the nature of the oxidizing species or establishes the mechanism of the induction of oxidation catalyzed by a concrete compound. In the case of a bulky catalyst molecule, the ratio of hydroxyl radical attack rates upon the acetonitrile molecule and alkane becomes higher. This can be expanded if we assume that the reactions of hydroxyl radicals occur in a cavity inside a voluminous catalyst molecule, where the ratio of the local concentrations of acetonitrile and alkane is higher than in the whole reaction volume. The works of the authors of this review in this field are described in more detail herein.

scholarly journals Application of Mineral Iron-Based Natural Catalysts in Electro-Fenton Process: A Comparative Study

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 57
Author(s):  
Zahra Heidari ◽  
Rasool Pelalak ◽  
Reza Alizadeh ◽  
Nihal Oturan ◽  
Saeed Shirazian ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Energy Consumption ◽  
Degradation Kinetics ◽  
Cost Effective ◽  
Electrical Energy ◽  
Process Efficiency ◽  
New Mineral ◽  
High Catalytic Activity ◽  
Pseudo First Order Reaction ◽  
Iron Based

The potential use of novel iron based mineral catalysts as an effective and available material for electrocatalytic oxidation of refractory contaminants by heterogeneous electro-Fenton (HEF) process was studied for the first time. For this purpose, four natural catalysts, namely ilmenite (FeTiO3), pyrite (FeS2), chromite (FeCr2O4), and chalcopyrite (CuFeS2) were selected as the source of ferrous iron (Fe2+) ions. The catalyst samples were appropriately characterized by X-ray diffraction (XRD) and RAMAN analysis. The degradation kinetics and mineralization rate of 0.2 mM antibiotic cefazolin (CFZ), as a contaminant of emerging concern, were comparatively investigated by HEF using the catalysts mentioned above. The effect of important experimental parameters such as catalysts loading and current on the process efficiency was investigated. Moreover, the performance of these new mineral catalysts was compared in term of CFZ degradation kinetics, mineralization power, mineralization current efficiency and electrical energy consumption. A greater enhancement in degradation/mineralization of CFZ was obtained when using chalcopyrite as the catalyst in HEF. The stability and reusability experiments demonstrated negligible decrease in catalytic activity of chalcopyrite after five consecutive runs. Besides, the rate constant for CFZ oxidation by hydroxyl radicals was estimated according the pseudo-first-order reaction kinetics. The empirical assessment, in addition to economic evaluation, confirmed that iron based mineral catalysts and specifically chalcopyrite could be an appropriate and cost-effective alternative catalyst for HEF due to its high catalytic activity, availability, eco-friendly nature and low energy consumption compared to other synthesized catalysts.

Liquid-Phase Catalytic Oxidation of Styrene by a Fiber-Supported Copper(II) Complex with High Catalytic Performance

2014 ◽  
Vol 1033-1034 ◽  
pp. 61-64 ◽  
Author(s):  
Hong Hong Yang ◽  
Ge Wang ◽  
Shan Shan Yan ◽  
Jing Feng ◽  
Zhen Dong Liu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Temperature ◽  
Supported Catalyst ◽  
Catalytic Performance ◽  
Subsequent Treatment ◽  
High Catalytic Activity ◽  
Reaction Conditions ◽  
Tert Butyl Hydroperoxide ◽  
New Type ◽  
Polymer Supported

A new type of polymer-supported catalyst, [PS-(PBIM)2Cu (II)], was synthesized by loading 2-(2’-pyridyl) benzimidazole on chloromethylated propylene-styrene graft copolymer fiber and subsequent treatment with Cu (OAc)2 in methanol. The prepared catalyst was used in the oxidation of styrene with tert-butyl hydroperoxide (TBHP) as the oxidant. The important reaction conditions, such as the reaction temperature, the ratio of oxidant/styrene, and the recycle times were examined. The experimental results show that the catalyst reveals relatively high catalytic performance with 84% conversion for styrene. The suitable conditions are as follows: n (styrene):n (TBHP)=1:3, the reaction temperature of 80 °C and the reaction time of 8 h. In addition, the catalyst used repeatedly for 3 times can still possess high catalytic activity.

Self-Supported FeP Nanorod Arrays: A Cost-Effective 3D Hydrogen Evolution Cathode with High Catalytic Activity

ACS Catalysis ◽  
2014 ◽  
Vol 4 (11) ◽  
pp. 4065-4069 ◽  
Author(s):  
Yanhui Liang ◽  
Qian Liu ◽  
Abdullah M. Asiri ◽  
Xuping Sun ◽  
Yonglan Luo
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Cost Effective ◽  
High Catalytic Activity ◽  
Nanorod Arrays

scholarly journals New Oxidovanadium(IV) Complexes with 2,2′-bipyridine and 1,10-phenathroline Ligands: Synthesis, Structure and High Catalytic Activity in Oxidations of Alkanes and Alcohols with Peroxides

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 217 ◽  
Author(s):  
Iakov Fomenko ◽  
Artem Gushchin ◽  
Pavel Abramov ◽  
Maksim Sokolov ◽  
Lidia Shul'pina ◽  
...  
Keyword(s):  
Xrd Analysis ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
Coordination Environment ◽  
Homogeneous Oxidation ◽  
Alkyl Hydroperoxides ◽  
Monomeric Complex ◽  
Tert Butyl Hydroperoxide ◽  
Distorted Octahedral

Reactions of [VCl3(thf)3] or VBr3 with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) in a 1:1 molar ratio in air under solventothermal conditions has afforded polymeric oxidovanadium(IV) four complexes 1–4 of a general formula [VO(L)X2]n (L = bpy, phen and X = Cl, Br). Monomeric complex [VO(DMF)(phen)Br2] (4a) has been obtained by the treatment of compound 4 with DMF. The complexes were characterized by IR spectroscopy and elemental analysis. The crystal structures of 3 and 4a were determined by an X-ray diffraction (XRD) analysis. The {VOBr2(bpy)} fragments in 3 form infinite chains due to the V = O…V interactions. The vanadium atom has a distorted octahedral coordination environment. Complexes 1–4 have been tested as catalysts in the homogeneous oxidation of alkanes (to produce corresponding alkyl hydroperoxides which can be easily reduced to alcohols by PPh3) and alcohols (to corresponding ketones) with H2O2 or tert-butyl hydroperoxide in MeCN. Compound 1 exhibited the highest activity. The mechanism of alkane oxidation was established using experimental selectivity and kinetic data and theoretical DFT calculations. The mechanism is of the Fenton type involving the generation of HO• radicals.

Pd anchored on C3N4 nanosheets/reduced graphene oxide: an efficient catalyst for the transfer hydrogenation of alkenes

2018 ◽  
Vol 42 (11) ◽  
pp. 9324-9331 ◽  
Author(s):  
Jie Li ◽  
Saisai Cheng ◽  
Tianxing Du ◽  
Ningzhao Shang ◽  
Shutao Gao ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Catalytic Activity ◽  
Hybrid Composite ◽  
Cost Effective ◽  
Pd Nanoparticles ◽  
Transfer Hydrogenation ◽  
High Catalytic Activity ◽  
Efficient Catalyst ◽  
Reduced Graphene ◽  
Hydrogen Donors

Pd nanoparticles anchored on g-C3N4 NS/rGO were prepared by means of a cost-effective and facile co-assembly approach. The hybrid composite showed high catalytic activity and stability for the hydrogenation of alkenes with FA and HCOONH4 as hydrogen donors.

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