scholarly journals An Unexpected Iron (II)-Based Homogeneous Catalytic System for Highly Efficient CO2-to-CO Conversion under Visible-Light Irradiation

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1878 ◽  
Author(s):  
Zi-Cheng Fu ◽  
Cheng Mi ◽  
Yan Sun ◽  
Zhi Yang ◽  
Quan-Qing Xu ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Monochromatic Light ◽  
Product Selectivity ◽  
Fuel Conversion ◽  
High Turnover ◽  
Experimental Conditions ◽  
Catalytic Systems ◽  
Highly Efficient ◽  
Co Conversion ◽  
Molecular Catalysts

We present two as-synthesized Fe(II)-based molecular catalysts with 1,10-phenanthroline (phen) ligands; Fe(phen)3Cl2 (1) and [Fe(phen)2(CH3CH2OH)Cl]Cl (2), and their robust catalytic properties for the conversion of CO2 to CO in DMF/TEOA (DMF = N,N’-dimethylformamide; TEOA = triethanolamine) solution containing Ru(bpy)32+ and BIH (1,3-dimethyl-2-phenyl-2,3- dihydro-1H-benzo-[d]-imidazole). High turnover numbers (TONs) of 19,376 were achieved with turnover frequencies (TOFs) of 3.07 s−1 for complex 1 (1.5 × 10−7 M). A quantum efficiency of 0.38% was observed after 5 h irradiated by 450 nm monochromatic light. The generation rate of CO2 and H2 were tuned by optimizing the experimental conditions, resulting in a high CO selectivity of 90%. The remarkable contribution of the photosensitizer to the total TONCO was found being 19.2% (as shown by tests under similar conditions without catalysts) when BIH was employed as a sacrificial electron donor. The product selectivity in complex 2 reached 95%, and the corresponding TONCO and TOFCO were 33,167 and 4.61 s−1 in the same concentration with complex 1 used as catalyst; respectively. This work provides guidance for future designs of simple, highly efficient and selective molecular catalytic systems that facilitate carbon-neutral solar-to-fuel conversion processes

Highly efficient and selective photocatalytic CO2 to CO conversion in aqueous solution

2020 ◽  
Vol 56 (27) ◽  
pp. 3851-3854 ◽  
Author(s):  
Xiaomin Chai ◽  
Hai-Hua Huang ◽  
Huiping Liu ◽  
Zhuofeng Ke ◽  
Wen-Wen Yong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Performance ◽  
Aqueous Media ◽  
Highly Efficient ◽  
Co Conversion

A Co-based complex displayed the highest photocatalytic performance for CO2 to CO conversion in aqueous media.

Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

2020 ◽  
Author(s):  
Laurent Sévery ◽  
Jacek Szczerbiński ◽  
Mert Taskin ◽  
Isik Tuncay ◽  
Fernanda Brandalise Nunes ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Heterogeneous Systems ◽  
Catalytic Systems ◽  
New Approach ◽  
Molecular Systems ◽  
Electrode Surfaces ◽  
Catalytic Surfaces ◽  
Oxide Electrodes ◽  
The Stability ◽  
Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Extreme Values ◽  
Catalytic Properties ◽  
Active Components ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Peroxide Decomposition ◽  
Two Component ◽  
Catalytically Active

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.

Oxidative ammonolysis of methylpyrazine over binary catalytic systems: III. Phosphorus-molybdenum system: Catalytic properties and the active component

2000 ◽  
Vol 41 (2) ◽  
pp. 222-230 ◽  
Author(s):  
V. M. Bondareva ◽  
T. V. Andrushkevich ◽  
N. N. Chumachenko ◽  
R. I. Maksimovskaya ◽  
L. M. Plyasova ◽  
...  
Keyword(s):  
Active Component ◽  
Catalytic Properties ◽  
Catalytic Systems ◽  
Oxidative Ammonolysis

Degradation of Amaranth azo dye in water by heterogeneous photo-Fenton process using FeWO4 catalyst prepared by microwave irradiation

2015 ◽  
Vol 73 (1) ◽  
pp. 88-94 ◽  
Author(s):  
Eric da Cruz Severo ◽  
Chayene Gonçalves Anchieta ◽  
Vitória Segabinazzi Foletto ◽  
Raquel Cristine Kuhn ◽  
Gabriela Carvalho Collazzo ◽  
...  
Keyword(s):  
Azo Dye ◽  
Fenton Reaction ◽  
Catalytic Properties ◽  
Interactive Effects ◽  
Fenton Process ◽  
Operational Parameters ◽  
Treatment Efficiency ◽  
Experimental Conditions ◽  
Decolorization Efficiency ◽  
Central Composite

FeWO4 particles were synthesized by a simple, rapid and facile microwave technique and their catalytic properties in heterogeneous photo-Fenton reaction were evaluated. This material was employed in the degradation of Amaranth azo dye. Individual and interactive effects of operational parameters such as pH, dye concentration and H2O2 dosage on the decolorization efficiency of Amaranth dye were evaluated by 23 central composite design. According to characterization techniques, a porous material and a well-crystallized phase of FeWO4 oxide were obtained. Regarding the photo-Fenton reaction assays, up to 97% color and 58% organic carbon removal were achieved in the best experimental conditions. In addition, the photo-Fenton process maintained treatment efficiency over five catalyst reuse cycles to indicate the durability of the FeWO4 catalyst. In summary, the results reveal that the synthesized FeWO4 material is a promising catalyst for wastewater treatment by heterogeneous photo-Fenton process.

Isomorphous rare-earth tris[bis(2,6-diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3-diene polymerization and in the inhibited oxidation of polydimethylsiloxane

2018 ◽  
Vol 74 (5) ◽  
pp. 590-598 ◽  
Author(s):  
Mikhail E. Minyaev ◽  
Alexander N. Tavtorkin ◽  
Sof'ya A. Korchagina ◽  
Galina N. Bondarenko ◽  
Andrei V. Churakov ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Catalytic Properties ◽  
Molar Ratio ◽  
High Catalytic Activity ◽  
Catalytic Systems ◽  
Neodymium Complex ◽  
Butadiene Polymerization ◽  
Bond Network ◽  
Phosphate Ligands ◽  
Monodentate Coordination

Crystals of mononuclear tris[bis(2,6-diisopropylphenyl) phosphato-κO]pentakis(methanol-κO)lanthanide methanol monosolvates of lanthanum, [La(C24H34O4P)3(CH3OH)5]·CH3OH, (1), cerium, [Ce(C24H34O4P)3(CH3OH)5]·CH3OH, (2), and neodymium, [Nd(C24H34O4P)3(CH3OH)5]·CH3OH, (3), have been obtained by reactions between LnCl3(H2O) n (n = 6 or 7) and lithium bis(2,6-diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds (1)–(3) crystallize in the monoclinic P21/c space group and have isomorphous crystal structures. All three bis(2,6-diisopropylphenyl) phosphate ligands display a κO-monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O2P(O-2,6-iPr2C6H3)2}3(CH3OH)5] molecular unit exhibits four intramolecular O—H...O hydrogen bonds, forming six-membered rings. The unit forms two intermolecular O—H...O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O2P(O-2,6-iPr2C6H3)2}3(CH3OH)5]·CH3OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen-bond network. Complexes (1)–(3) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound (2) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6-diisopropylphenyl) phosphato-κO]neodymium, (3′), which was obtained as a dry powder of (3) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.

Improving C11+ Hydrocarbon Product Selectivity by Hydrogen Distribution in Fischer-Tropsch Synthesis

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Shahram Sharifnia ◽  
A. Khodadadi ◽  
Y. Mortazavi
Keyword(s):  
Strong Dependence ◽  
Operating Pressure ◽  
Product Selectivity ◽  
Hydrogen Distribution ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Ft Synthesis ◽  
Co Conversion ◽  
Methane Selectivity ◽  
Hydrocarbon Product

The present study examines the effect of hydrogen distribution (HD) along a Co/SiO2 catalyst bed on Fischer-Tropsch (FT) synthesis. The synthesis is performed under two pressures of 1.0 and 9.0 atm and different H2/CO ratios. The results are compared to those of the usual co-feed, in which both CO and H2 are introduced to the bed inlet. By HD strategy, the methane selectivity is suppressed by as much as 25% and the C11+ selectivity is enhanced up to 26%. CO conversion and product selectivity exhibited a strong dependence on the operating pressure and H2/CO ratio, when hydrogen is distributed.

l-Methionine–Pd complex supported on hercynite as a highly efficient and reusable nanocatalyst for C–C cross-coupling reactions

2020 ◽  
Vol 44 (7) ◽  
pp. 2919-2929 ◽  
Author(s):  
Masoud Mohammadi ◽  
Arash Ghorbani-Choghamarani
Keyword(s):  
Catalytic Properties ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Highly Efficient ◽  
Cross Coupling Reactions

An l-methionine–Pd complex was covalently immobilized on the surface of hercynite (FeAl2O4) MNPs, and its catalytic properties were studied in C–C coupling reactions.

“Water soluble” palladium nanoparticle engineering for C–C coupling, reduction and cyclization catalysis

2019 ◽  
Vol 21 (24) ◽  
pp. 6646-6657 ◽  
Author(s):  
A. Iben Ayad ◽  
C. Belda Marín ◽  
E. Colaco ◽  
C. Lefevre ◽  
C. Méthivier ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Water Soluble ◽  
Organic Reactions ◽  
Palladium Nanoparticle ◽  
High Turnover ◽  
Highly Efficient ◽  
Ppm Level

Water stable Pd-NPs prepared in an eco-friendly manner enable highly efficient catalysis of 6 organic reactions in aqueous media with quantities of Pd down to the ppm level and high turnover frequencies.

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