In Search of Catalytically Active Species in the Surfactant-Mediated Biphasic Alkene Epoxidation with Mimoun-Type Complexes

2001 ◽  
Vol 3 (3) ◽  
pp. 329-332 ◽  
Author(s):  
Dirk V. Deubel ◽  
Jörg Sundermeyer ◽  
Gernot Frenking
Keyword(s):  
Active Species ◽  
Catalytically Active

Sewage sludge as a precursor of adsorbents/catalysts for environmental applications

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Ros ◽  
C. Canals-Batlle ◽  
M.A. Lillo-Ródenas ◽  
E. Fuente ◽  
M. A. Montes-Morán ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Room Temperature ◽  
Waste Water Treatment ◽  
Textural Properties ◽  
Active Species ◽  
Elemental Sulphur ◽  
Gaseous Emissions ◽  
Removal Experiments ◽  
Catalytically Active

This paper focuses on the valorisation of solid residues obtained from the thermal treatment of sewage sludge. In particular, sewage sludge samples were collected from two waste water treatment plants (WWTPs) with different sludge line basic operations. After drying, sludges were heated up to 700 °C in appropriate ovens under diluted air (gasification) and inert (pyrolysis) atmospheres. The solids obtained, as well as the dried (raw) sludges, were characterised to determine their textural properties and chemical composition, including the speciation of their inorganic fraction. All the materials under study were employed as adsorbents/catalysts in H2S removal experiments at room temperature. It was found that, depending on the particular sludge characteristics, outstanding results can be achieved both in terms of retention capacities and selectivity. Some of the solids outperform commercially available sorbents specially designed for gaseous emissions control. In these adsorbents/catalysts, H2S is selectively oxidised to elemental sulphur most likely due to the presence of inorganic, catalytically active species. The role of the carbon-enriched part on these solids is also remarked.

Probing the Catalytically Active Species in POM‐catalysed DNA‐model Hydrolysis

2021 ◽  
Author(s):  
Frederico F Martins ◽  
Ángel Sánchez-González ◽  
Jose Lanuza ◽  
Haralampos N. Miras ◽  
Xabier Lopez ◽  
...  
Keyword(s):  
Active Species ◽  
Catalytically Active

scholarly journals Shedding light on the nature of the catalytically active species in photocatalytic reactions using Bi2O3 semiconductor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Paola Riente ◽  
Mauro Fianchini ◽  
Patricia Llanes ◽  
Miquel A. Pericàs ◽  
Timothy Noël
Keyword(s):  
Experimental Studies ◽  
Heterogeneous Photocatalysis ◽  
Active Species ◽  
Organic Transformations ◽  
Alkyl Bromides ◽  
Catalytically Active ◽  
Visible Light Driven ◽  
Photocatalytic Reactions ◽  
Insight Into ◽  
Photocatalytic Processes

AbstractThe importance of discovering the true catalytically active species involved in photocatalytic systems allows for a better and more general understanding of photocatalytic processes, which eventually may help to improve their efficiency. Bi2O3 has been used as a heterogeneous photocatalyst and is able to catalyze several synthetically important visible-light-driven organic transformations. However, insight into the operative catalyst involved in the photocatalytic process is hitherto missing. Herein, we show through a combination of theoretical and experimental studies that the perceived heterogeneous photocatalysis with Bi2O3 in the presence of alkyl bromides involves a homogeneous BinBrm species, which is the true photocatalyst operative in the reaction. Hence, Bi2O3 can be regarded as a precatalyst which is slowly converted in an active homogeneous photocatalyst. This work can also be of importance to mechanistic studies involving other semiconductor-based photocatalytic processes.

scholarly journals Surprisingly high sensitivity of copper nanoparticles toward coordinating ligands: consequences for the hydride reduction of benzaldehyde

2018 ◽  
Vol 8 (19) ◽  
pp. 5073-5080 ◽  
Author(s):  
Xavier Frogneux ◽  
Ferenc Borondics ◽  
Stéphane Lefrançois ◽  
Florian D'Accriscio ◽  
Clément Sanchez ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
High Sensitivity ◽  
Active Species ◽  
Hydride Reduction ◽  
Catalytically Active

Depending on the ligand, ligand-induced leaching of copper nanoparticles may produce catalytically active species for the reduction of benzaldehyde.

scholarly journals Unprecedentedly High Activity and/or High Regio-/Stereoselectivity of Fluorenyl-Based CGC Allyl-Type η3:η1-tert-Butyl(dimethylfluorenylsilyl)amido Ligated Rare Earth Metal Monoalkyl Complexes in Olefin Polymerization

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 836
Author(s):  
Ge Guo ◽  
Xiaolu Wu ◽  
Xiangqian Yan ◽  
Li Yan ◽  
Xiaofang Li ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Active Species ◽  
Metal Centers ◽  
Tert Butyl ◽  
Alkyl Groups ◽  
Elemental Analyses ◽  
Catalytically Active ◽  
Geometry Configuration

A series of fluorenyl-based constrained-geometry-configuration (CGC) allyl-type rare earth metal monoalkyl complexes bearing the divalent anionic η3:η1-tert-butyl(dimethylfluorenylsilyl)amido (η3:η1-FluSiMe2NtBu) ligand (η3:η1-FluSiMe2NtBu)Ln(CH2SiMe3)(THF)2 (1–3) have been synthesized via the alkane elimination reaction between the FluHSiMe2NHtBu ligand and rare earth metal tri(trimethylsilylmethyl) complexes Ln(CH2SiMe3)3(THF)n. Their structures are characterized by means of NMR spectrum, elemental analyses, and X-ray diffraction. These complexes 1–3 are isostructural and isomorphous, and each of them adopts a distorted-trigonal-bipyramidal configuration containing one η3:η1-FluSiMe2NtBu ligand, one CH2SiMe3 ligand, and two THF molecules. Unlike traditional CGC allyl-type rare earth metal complexes showing no or low activity and regio-/stereoselectivity in styrene or MMA polymerization, these complexes 1–3 exhibit high catalytic activities and/or high regio-/stereoselectivities in the cis-1,4-polymerization of isoprene and myrcene or in the syndiotactic polymerization of styrene under the aid of different activators (borate or borane) and AlR3. The in situ 1H NMR spectra suggest that the exchanges of chelating ligands such as alkyl groups and divalent anionic η3:η1-FluSiMe2NtBu ligands between rare earth metal centers and Al centers result in the formation of a heterobimetallic tetraalkylaluminate complex R2Al(μ-R)2Ln(R)(μ-R)2AlR2, which is activated by activators to form a divalent cationic species [Ln(μ-R)2AlR2]2+ as a catalytically active species in the coordination–insertion polymerization of olefins.

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