Improved insight into catalytic reactions by kinetic modelling and LIF detection of intermediate radical species

1989 ◽  
pp. 424-425
Author(s):  
E. Fridell ◽  
B. Hellsing ◽  
S. Ljungström ◽  
T. Wahnström ◽  
A. Rosé ◽  
...  
Nanoscale ◽  
2015 ◽  
Vol 7 (40) ◽  
pp. 16952-16959 ◽  
Author(s):  
Kaige Zhang ◽  
Gongke Li ◽  
Yuling Hu

The surface-enhanced Raman spectroscopy (SERS) technique is of great importance for insight into the transient reaction intermediates and mechanistic pathways involved in heterogeneously catalyzed chemical reactions under actual reaction conditions, especially in water.


2020 ◽  
Vol 44 (44) ◽  
pp. 19103-19112
Author(s):  
Monika ◽  
Azaj Ansari

This work is based on a deep insight into a comparative study of C–H vs. O–H bond activation of allylic compound by the high valent iron complex. Our theoretical findings can help to design catalysts with better efficiency for catalytic reactions.


2004 ◽  
Vol 30/31 ◽  
pp. 311-317 ◽  
Author(s):  
I. Manuel ◽  
C. Thomas ◽  
H. Colas ◽  
N. Matthess ◽  
G. Djéga-Mariadassou

2020 ◽  
Vol 173 ◽  
pp. 111-118
Author(s):  
Rhys David Williams ◽  
Andrea Lucca Fabris ◽  
Aaron Knoll

2010 ◽  
Vol 20 (3) ◽  
pp. 125-131 ◽  
Author(s):  
Pavel A. Belyakov ◽  
Valentine I. Kadentsev ◽  
Alexander O. Chizhov ◽  
Natal’ya G. Kolotyrkina ◽  
Alexander S. Shashkov ◽  
...  

MRS Bulletin ◽  
2006 ◽  
Vol 31 (9) ◽  
pp. 669-674 ◽  
Author(s):  
J.K. Nørskov ◽  
M. Scheffler ◽  
H. Toulhoat

AbstractSolid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large amount of experimental data gathered during the last decades. This article shows how density functional theory can be used to describe the state of the surface during reactions and the rate of catalytic reactions. It will also show how we are beginning to understand the variation in catalytic activity from one transition metal to the next. Finally, the prospects of using calculations to guide the development of new catalysts in industry will be discussed.


2018 ◽  
Author(s):  
◽  
Luay Jaf

Numerous reactions take place within a polyurethane polymerization process. Homogeneous and catalytic reactions occur at the same time and intermediate compounds are formed. As the reaction proceeds, long chains of polymer are formed which drastically affect the kinetics of the reaction. Temperature and viscosity profiles of the reacting mixture are two strong indicators of the extent of reaction and the way the reactions are carried out. Therefore, simulating polyurethane gel and foam systems helps interpret temperature and viscosity profiles and gain insight into the kinetics of the system. Using MATLAB program, a model was introduced which simultaneously solves over 80 ordinary differential equations and provide temperature and viscosity profiles as well as concentration profiles, degrees of polymerization, gel point and foam height for individual formulations. Experimental data were used to validate the code showing the model is fundamentally correct. Simulation results showed good fits to the experimental data providing reaction kinetics of the system. The model was modified to simulate reaction systems with minimal change in kinetic parameters. Finally, the simulation studies of this research provide fundamental insights into mechanism of homogenous and catalytic reactions. This research process places high demands on identifying and testing highly-impacting fundamental mechanism during polymerization that have not previously been identified.


1974 ◽  
Vol 52 (1) ◽  
pp. 102-110 ◽  
Author(s):  
Allen John Elliot ◽  
Frank Cuthbert Adam

Dilute solutions of aliphatic thiols have been prepared and photolyzed at 253.7 nm in 3-methylpentane glasses at 77°K. The major products formed initially are thiyl radicals RS• and hydrogen atoms. Both of these are hot and yield solvent radicals by abstraction reactions, and relatively small amounts of RS2•, RS•, and possibly R1R2C=S. Thermal annealing of the matrices is accompanied by loss of hydrocarbon radicals through cage reactions and concommitant increase in the RS• concentration. An intermediate radical of the type R1R2ĊSH may also be produced in the annealing process. The photometric and spin resonance characteristics of RS•, RS2•and R1ĊH—SH are discussed and related to other systems in which these intermediates are observed. RS• is characterized in the amorphous phase by an absorption at 405 nm and a broad asymmetrical e.p.r. resonance near [Formula: see text] RS2• has a non-axial g-tensor with principal values of about 2.06, 2.02, and 2.00 and has no detectable absorptions between 350 and 1200 nm.The photolytic behavior of these metastable radical species is also investigated.


2003 ◽  
Vol 36 (26) ◽  
pp. 9687-9690 ◽  
Author(s):  
F. M. Calitz ◽  
J. B. McLeary ◽  
J. M. McKenzie ◽  
M. P. Tonge ◽  
B. Klumperman ◽  
...  

Author(s):  
F.M. Leibsle

Scanning tunneling microscopy (STM) can image clean and adsorbate-covered surfaces with atomic/molecular resolution. This enables us to obtain detailed information on how catalytic reactions proceed on surfaces. Information on such topics as initiation sites for chemical reactions, reaction trends, the development of molecular order, and mesoscopic surface restructuring can be obtained. In addition, variable temperature STM experiments can yield insight into the decomposition of molecules at surfaces.Studies using STM under ultra-high vaccuum conditions have shown how the oxidation of CO occurs on oxygen-precovered Rh(110) surfaces. Figure 1 shows an STM image of an oxygen-precovered Rh(110) surface displaying areas of oxygen-induced c(2×6) and c(2×8) reconstructions following exposure to 5 Langmuirs of CO. Images like this show that the reaction between the CO and adsorbed oxygen initiates at step edges and defects sites. The CO reaction fronts then proceed in a onedimensional manner stripping away the oxgyen from two and three atom wide islands.


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