The activity of homogeneous and heterogenized Rh(I) complexes in hydrogenation of alkenes

1979 ◽  
Vol 44 (9) ◽  
pp. 2624-2632 ◽  
Author(s):  
Zdeněk Kozák ◽  
Martin Čapka
Keyword(s):  
Liquid Phase ◽  
Pore Size ◽  
Supported Catalysts ◽  
Supported Catalyst ◽  
First Order ◽  
Liquid Phase Hydrogenation ◽  
Kinetics Of ◽  
Soluble Complexes

Kinetics of liquid phase hydrogenation of alkenes catalysed by homogeneous Rh(I) complexes prepared in situ from di-μ,μ'-chloro-bis/di(cyclooctene)rhodium/ and 3-(triethoxysilyl)propyldiphenylphosphine and by heterogenised analogues anchored to silica have been studied. The reaction was found to be first order in hydrogen, alkene and catalyst. Compared to the soluble complexes, the supported catalyst turned out to be substantially more stable. At 0.3-0.6%Rh concentrations on the support, the activity of the catalyst was not affected by pore size within 4-10 nm region. The supported catalysts prepared by functionalization of the support followed by formation of the Rh complex were more active then their homogeneous analogues.

In Situ Measurement of Dissolved Hydrogen during the Liquid-Phase Hydrogenation of DinitrilesMethod and Case Study

2005 ◽  
Vol 44 (25) ◽  
pp. 9770-9775 ◽  
Author(s):  
Peter Schärringer ◽  
Thomas E. Müller ◽  
Wolfgang Kaltner ◽  
Johannes A. Lercher
Keyword(s):  
Liquid Phase ◽  
In Situ Measurement ◽  
Liquid Phase Hydrogenation ◽  
Dissolved Hydrogen

Preparation of ZnO/PANI Nanocomposite and Study on its Photocatalytic Properties

2013 ◽  
Vol 716 ◽  
pp. 368-372
Author(s):  
Hui Xu ◽  
Jian Wei Xing
Keyword(s):  
Charge Separation ◽  
In Situ Polymerization ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Aniline Monomer ◽  
First Order ◽  
Photocatalytic Activities ◽  
Recombination Centers ◽  
Kinetics Of

Polyaniline (PANI)/zinc oxide (ZnO) nanocomposites have been synthesized by in-situ polymerization of aniline monomer with ZnO nanomaterials. The PANI/ZnO nanocomposites were used as photocatalyst in the photodegradation of methylene blue dye (MB) molecules in aqueous solution. The results showed that PANI/ZnO nanocomposite greatly enhanced photocatalytic activities compared with pristine polyaniline might due to high photoexcited electronhole pairs charge separation. The photocatalytic activities of PANI/ZnO nanocomposites increased with increasing ZnO content, however, further increasing ZnO content over 50% induced the formation of more agglomerates, which could act as recombination centers of photoexcited electronhole pairs, leading to decreased photocatalytic activity. The kinetics of photodegradation of MB dye using PANI/ZnO(ZnO content 50 % ) nanocomposites photocatalyst was found to be of the first order.

Feasibility Study of Raman Spectroscopy as a Tool to Investigate the Liquid-Phase Chemistry of Aliphatic Organic Peroxides

1997 ◽  
Vol 51 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Peter Jacob ◽  
Bernhard Wehling ◽  
Wieland Hill ◽  
Dieter Klockow
Keyword(s):  
Hydrogen Peroxide ◽  
Raman Spectroscopy ◽  
Liquid Phase ◽  
Chemical Processes ◽  
Organic Peroxides ◽  
Time Resolved ◽  
In Situ Investigation ◽  
Phase Chemistry ◽  
Kinetics Of

The described investigations are focused on peroxides occurring as products in atmospheric chemical processes, namely, hydrogen peroxide, methylhydroperoxide, hydroxymethylhydroperoxide, bis-(hydroxymethyl)peroxide, 1-hydroxyethylhydroperoxide, bis-(hydroxyethyl)peroxide, and hydroxymethylmethylperoxide. The compounds are identified and determined through the position and intensity of their characteristic O–O stretching bands in the range between 767 and 878 cm−1. Time-resolved Raman spectroscopy of peroxide solutions permits the in situ investigation of pathways and kinetics of reactions between peroxides and aldehydes.

Kinetics of liquid-phase hydrogenation of isooctenes on a Pd/γ-alumina catalyst

AIChE Journal ◽  
2006 ◽  
Vol 52 (3) ◽  
pp. 1142-1156 ◽  
Author(s):  
Amitava Sarkar ◽  
Deepyaman Seth ◽  
Flora T. T. Ng ◽  
Garry L. Rempel
Keyword(s):  
Liquid Phase ◽  
Alumina Catalyst ◽  
Liquid Phase Hydrogenation ◽  
Kinetics Of

scholarly journals Heparin-stimulated inhibition of factor IXa generation and factor IXa neutralization in plasma

Blood ◽  
1990 ◽  
Vol 76 (3) ◽  
pp. 549-554
Author(s):  
J Pieters ◽  
T Lindhout ◽  
G Willems
Keyword(s):  
Unfractionated Heparin ◽  
Rate Constant ◽  
Calcium Ions ◽  
Order Rate Constant ◽  
Free Calcium ◽  
First Order ◽  
Factor Ixa ◽  
Factor Xia ◽  
Kinetics Of

Generation and inhibition of activated factor IXa was studied in factor XIa-activated plasma containing 4 mmol/L free calcium ions and 20 mumol/L phospholipid (25 mol% phosphatidylserine/75 mol% phosphatidylcholine). Interference of other (activated) clotting factors with the factor IXa activity measurements could be avoided by using a highly specific and sensitive bioassay. Factor IXa generation curves were analyzed according to a model that assumed Michaelis-Menten kinetics of factor XIa-catalyzed factor IXa formation and pseudo first order kinetics of inhibition of factor XIa and factor IXa. In the absence of heparin, factor IXa activity in plasma reached final levels that were found to increase with increasing amounts of factor XIa used to activate the plasma. When the model was fitted to this set of factor IXa generation curves, the analysis yielded a rate constant of inhibition of factor XIa of 0.7 +/- 0.1 min-1 and a kcat/Km ratio of 0.29 +/- 0.01 (nmol/L)-1 min-1. No neutralization of factor IXa activity was observed (the estimated rate constant of inhibition of factor IXa was 0). Thus, in the absence of heparin, the final level of factor IXa in plasma is only dependent on the initial factor XIa concentration. While neutralization of in situ generated factor IXa in normal plasma was negligible, unfractionated heparin dramatically enhanced the rate of inactivation of factor IXa (apparent second order rate constant of inhibition of 5.2 min-1/per microgram heparin/mL). The synthetic pentasaccharide heparin, the smallest heparin chain capable of binding antithrombin III, stimulated the inhibition of in situ generated factor IXa, but sevenfold less than unfractionated heparin (k = 0.76 min-1 per microgram pentasaccharide/mL). We found that free calcium ions were absolutely required to observe an unfractionated heparin and pentasaccharide-stimulated neutralization of factor IXa activity. Factor XIa inhibition (psuedo first order rate constant of 0.7 min-1) was not affected by unfractionated heparin or pentasaccharide in the range of heparin concentrations studied.

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