Titre :

The Kinetics of the Reaction C2H5• + HI → C2H6 + I• over an extended Temperature Range (213 - 623 K): Experiment and Modeling

Auteur(s) :

Leplat, Nicholas [Auteur]
Federic, Jozef [Auteur]
Commenius University in Bratislava - Univerzita Komenského
Sulkova, Katarina [Auteur]
Trnava University
Sudolska, Maria [Auteur]
LOUIS, Florent [Auteur]
Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 [PC2A]
Cernusak, Ivan [Auteur]
Commenius University in Bratislava - Univerzita Komenského
Rossi, Michel Jean [Auteur]
Laboratory of Atmospheric Chemistry [Paul Scherrer Institute] [LAC]

Titre de la revue :

Zeitschrift für Physikalische Chemie

Nom court de la revue :

Z. Phys. Chem.

Numéro :

229

Pagination :

Pages 1475-1502

Date de publication :

2015-09

Mot(s)-clé(s) en anglais :

Ethyl Free Radical
H-Metathesis
Reaction Rate Constant
Temperature Dependence
Arrhenius Rate Parameters
ab initio Calculations
Potential Energy Surface
Spin-Orbit Interaction

Discipline(s) HAL :

Chimie/Chimie théorique et/ou physique
Physique [physics]/Physique [physics]/Chimie-Physique [physics.chem-ph]

Résumé en anglais : [en]

The present study reports temperature dependent rate constants k1 for the title reaction across the temperature range 213 to 293 K obtained in a Knudsen flow reactor equipped with an external free radical source based on ...
Lire la suite >The present study reports temperature dependent rate constants k1 for the title reaction across the temperature range 213 to 293 K obtained in a Knudsen flow reactor equipped with an external free radical source based on the reaction C2H5I + H• → C2H5• + HI and single VUV-photon ionization mass spectrometry using Lyman-α radiation of 10.2 eV. Combined with previously obtained high-temperature data of k1 in the range 298–623 K using the identical experimental equipment and based on the kinetics of C2H5• disappearance with increasing HI concentration we arrive at the following temperature dependence best described by a three-parameter fit to the combined data set: k1 = (1.89 ± 1.19)10−13(T/298)2.92±0.51 exp ((3570 ± 1500)/RT), R = 8.314 J mol–1 K–1 in the range 213–623 K. The present results confirm the general properties of kinetic data obtained either in static or Knudsen flow reactors and do nothing to reconcile the significant body of data obtained in laminar flow reactors using photolytic free radical generation and suitable free radical precursors. The resulting rate constant for wall-catalyzed disappearance of ethyl radical across the full temperature range is discussed. Highly correlated ab initio quantum chemistry methods and canonical transition state theory were applied for the reaction energy profiles and rate constants. Geometry optimizations of reactants, products, molecular complexes, and transition states are determined at the CCSD/cc-pVDZ level of theory. Subsequent single-point energy calculations employed the DK-CCSD(T)/ANO-RCC level. Further improvement of electronic energies has been achieved by applying spin-orbit coupling corrections towards full configuration interaction and hindered rotation analysis of vibrational contributions. The resulting theoretical rate constants in the temperature range 213–623 K lie in the range E-11–E-12 cm3 molecule–1 s–1, however experiments and theoretical modelling seem at great odds with each other.Lire moins >

Langue :

Anglais

Audience :

Internationale

Vulgarisation :

Non

Établissement(s) :

Université de Lille
CNRS

Collections :

• Physicochimie des Processus de Combustion et de l'Atmosphère (PC2A) - UMR 8522

Équipe(s) de recherche :

Cinétique chimique, Combustion, Réactivité (C3R) : Sûreté Nucléaire

Date de dépôt :

2018-11-27T14:37:23Z
2020-10-05T10:48:43Z