Model Ziegler-Natta .alpha.-Olefin Polymerization Catalysts Derived from[{(.eta.5-C5Me4)SiMe2(.eta.1-NCMe3)}(PMe3)Sc(.mu.2-H)]2 and[{(.eta.5-C5Me4)SiMe2(.eta.1-NCMe3)}Sc(.mu.2-CH2CH2CH3)]2. Synthesis, Structures, and Kinetic and Equilibrium Investigations of the Catalytically Active Species in Solution

1994 ◽  
Vol 116 (11) ◽  
pp. 4623-4640 ◽  
Author(s):  
Pamela J. Shapiro ◽  
William P. Schaefer ◽  
Jay A. Labinger ◽  
John E. Bercaw ◽  
W. Donald Cotter
Keyword(s):  
Olefin Polymerization ◽  
Active Species ◽  
Polymerization Catalysts ◽  
Alpha Olefin ◽  
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

Highly Efficient Carborane-Based Activators for Molecular Olefin Polymerization Catalysts

ACS Catalysis ◽  
2021 ◽  
pp. 3335-3342
Author(s):  
S. Olivia Gunther ◽  
Qingheng Lai ◽  
Todd Senecal ◽  
Rafael Huacuja ◽  
Sean Bremer ◽  
...  
Keyword(s):  
Olefin Polymerization ◽  
Polymerization Catalysts ◽  
Highly Efficient

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.

Chiral, non-C2 symmetric zirconocene complexes as catalysts for stereoregular .alpha.-olefin polymerization

1993 ◽  
Vol 115 (8) ◽  
pp. 3326-3327 ◽  
Author(s):  
Michael A. Giardello ◽  
Moris S. Eisen ◽  
Charlotte L. Stern ◽  
Tobin J. Marks
Keyword(s):  
Olefin Polymerization ◽  
Alpha Olefin
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