Role of O2 + QOOH in Low-Temperature Ignition of Propane. 1. Temperature and Pressure Dependent Rate Coefficients

2012 ◽  
Vol 116 (13) ◽  
pp. 3325-3346 ◽  
Author(s):  
C. Franklin Goldsmith ◽  
William H. Green ◽  
Stephen J. Klippenstein
Keyword(s):  
Low Temperature ◽  
Rate Coefficients ◽  
Dependent Rate ◽  
Temperature And Pressure

Reaction of Hydroxyl Radicals with C4H5N (Pyrrole): Temperature and Pressure Dependent Rate Coefficients

2012 ◽  
Vol 116 (24) ◽  
pp. 6051-6058 ◽  
Author(s):  
Terry J. Dillon ◽  
Maria E. Tucceri ◽  
Katrin Dulitz ◽  
Abraham Horowitz ◽  
Luc Vereecken ◽  
...  
Keyword(s):  
Hydroxyl Radicals ◽  
Rate Coefficients ◽  
Dependent Rate ◽  
Temperature And Pressure

Pressure-dependent rate constants for PAH growth: formation of indene and its conversion to naphthalene

2016 ◽  
Vol 195 ◽  
pp. 637-670 ◽  
Author(s):  
Alexander M. Mebel ◽  
Yuri Georgievskii ◽  
Ahren W. Jasper ◽  
Stephen J. Klippenstein
Keyword(s):  
Rate Constants ◽  
Potential Energy Surfaces ◽  
Major Product ◽  
Rate Coefficients ◽  
Dependent Rate ◽  
Master Equation Approach ◽  
Polycyclic Aromatic ◽  
Growth Formation ◽  
Energy Surfaces

Unraveling the mechanisms for growth of polycyclic aromatic hydrocarbons (PAHs) requires accurate temperature- and pressure-dependent rate coefficients for a great variety of feasible pathways. Even the pathways for the formation of the simplest PAHs, indene and naphthalene, are fairly complex. These pathways provide important prototypes for modeling larger PAH growth. In this work we employ the ab initio RRKM theory-based master equation approach to predict the rate constants involved in the formation of indene and its conversion to naphthalene. The reactions eventually leading to indene involve C9Hx (x = 8–11) potential energy surfaces (PESs) and include C6H5 + C3H4 (allene and propyne), C6H6 + C3H3, benzyl + C2H2, C6H5 + C3H6, C6H6 + C3H5 and C6H5 + C3H5. These predictions allow us to make a number of valuable observations on the role of various mechanisms. For instance, we demonstrate that reactions which can significantly contribute to the formation of indene include phenyl + allene and H-assisted isomerization to indene of its major product, 3-phenylpropyne, benzyl + acetylene, and the reactions of the phenyl radical with propene and the allyl radical, both proceeding via the 3-phenylpropene intermediate. 3-Phenylpropene can be activated to a 1-phenylallyl radical, which in turn rapidly decomposes to indene. Next, indene can be converted to benzofulvene or naphthalene under typical combustion conditions, via its activation by H atom abstraction and methyl substitution on the five-membered ring followed by isomerization and decomposition of the resulting 1-methylindenyl radical, C10H9 → C10H8 + H. Alternatively, the same region of the C10H9 PES can be accessed through the reaction of benzyl with propargyl, C7H7 + C3H3 → C10H10 → C10H9 + H, which therefore can also contribute to the formation of benzofulvene or naphthalene. Benzofulvene easily transforms to naphthalene by H-assisted isomerization. An analysis of the effect of pressure on the reaction outcome and relative product yields is given, and modified Arrhenius fits of the rate constants are reported for the majority of the considered reactions. Ultimately, the implementation of such expressions in detailed kinetic models will help quantify the role of these reactions for PAH growth in various environments.

scholarly journals Temperature-(208–318 K) and pressure-(18–696 Torr) dependent rate coefficients for the reaction between OH and HNO<sub>3</sub>

2018 ◽  
Vol 18 (4) ◽  
pp. 2381-2394 ◽  
Author(s):  
Katrin Dulitz ◽  
Damien Amedro ◽  
Terry J. Dillon ◽  
Andrea Pozzer ◽  
John N. Crowley
Keyword(s):  
Cross Sections ◽  
Pressure Dependence ◽  
Low Temperatures ◽  
Room Temperature ◽  
Rate Coefficients ◽  
Title Reaction ◽  
Data Set ◽  
Dependent Rate ◽  
Temperature And Pressure

Abstract. Rate coefficients (k5) for the title reaction were obtained using pulsed laser photolytic generation of OH coupled to its detection by laser-induced fluorescence (PLP–LIF). More than 80 determinations of k5 were carried out in nitrogen or air bath gas at various temperatures and pressures. The accuracy of the rate coefficients obtained was enhanced by in situ measurement of the concentrations of both HNO3 reactant and NO2 impurity. The rate coefficients show both temperature and pressure dependence with a rapid increase in k5 at low temperatures. The pressure dependence was weak at room temperature but increased significantly at low temperatures. The entire data set was combined with selected literature values of k5 and parameterised using a combination of pressure-dependent and -independent terms to give an expression that covers the relevant pressure and temperature range for the atmosphere. A global model, using the new parameterisation for k5 rather than those presently accepted, indicated small but significant latitude- and altitude-dependent changes in the HNO3 ∕ NOx ratio of between −6 and +6 %. Effective HNO3 absorption cross sections (184.95 and 213.86 nm, units of cm2 molecule−1) were obtained as part of this work: σ213.86  =  4.52−0.12+0.23  ×  10−19 and σ184.95  =  1.61−0.04+0.08  ×  10−17.

Kinetic Analysis of Complex Chemical Activation and Unimolecular Dissociation Reactions using QRRK Theory and the Modified Strong Collision Approximation

2000 ◽  
Vol 214 (11) ◽  
Author(s):  
A.Y. Chang ◽  
J.W. Bozzelli ◽  
A.M. Dean
Keyword(s):  
Chemical Activation ◽  
Peroxy Radical ◽  
Dissociation Rate ◽  
Rate Coefficients ◽  
Unimolecular Dissociation ◽  
Frequency Model ◽  
Dependent Rate ◽  
Vinyl Radical ◽  
Temperature And Pressure ◽  
Collision Approximation

A method to predict temperature and pressure-dependent rate coefficients for complex bimolecular chemical activation and unimolecular dissociation reactions is described. A three-frequency version of QRRK theory is developed and collisional stabilization is estimated using the modified strong-collision approximation. The methodology permits analysis of reaction systems with an arbitrary degree of complexity in terms of the number of isomer or product channels. Specification of both high and low pressure limits is also provided. The chemically activated reaction of vinyl radical with molecular oxygen is used to demonstrate the approach. Subsequent dissociation of the stabilized vinyl peroxy radical is used to illustrate prediction of dissociation rate coefficients. These calculations confirm earlier results that the vinoxy + O channel is dominant under combustion conditions. The results are also consistent with RRKM results using the same input conditions. This approach provides a means to provide reasonably accurate predictions of the rate coefficients that are required in many detailed mechanisms. The major advantage is the ability to provide reasonable estimates of rate coefficients for many complex systems where detailed information about the transition states is not available. It is also shown that a simpler 1-frequency model appears adequate for high temperature conditions.

Temperature and Pressure-Dependent Rate Coefficients for the Reaction of Vinyl Radical with Molecular Oxygen

2015 ◽  
Vol 119 (28) ◽  
pp. 7766-7779 ◽  
Author(s):  
C. Franklin Goldsmith ◽  
Lawrence B. Harding ◽  
Yuri Georgievskii ◽  
James A. Miller ◽  
Stephen J. Klippenstein
Keyword(s):  
Molecular Oxygen ◽  
Rate Coefficients ◽  
Dependent Rate ◽  
Vinyl Radical ◽  
Temperature And Pressure

Temperature and Pressure Dependent Rate Coefficients for the Reaction of Ketene with Hydroxyl Radical

2019 ◽  
Vol 123 (13) ◽  
pp. 2483-2496 ◽  
Author(s):  
Boyang Xu ◽  
Julian Garrec ◽  
André Nicolle ◽  
Mickaël Matrat ◽  
Laurent Catoire
Keyword(s):  
Hydroxyl Radical ◽  
Rate Coefficients ◽  
Dependent Rate ◽  
Temperature And Pressure

scholarly journals Temperature (208–318 K) and pressure (18–696 Torr) dependent rate coefficients for the reaction between OH and HNO<sub>3</sub>

2017 ◽  
Author(s):  
Katrin Dulitz ◽  
Damien Amedro ◽  
Terry J. Dillon ◽  
Andrea Pozzer ◽  
John N. Crowley
Keyword(s):  
Cross Sections ◽  
Pressure Dependence ◽  
Low Temperatures ◽  
Room Temperature ◽  
Rate Coefficients ◽  
Title Reaction ◽  
Dependent Rate ◽  
Temperature And Pressure ◽  
Entire Dataset

Abstract. Rate coefficients (k5) for the title reaction were obtained using pulsed laser photolytic generation of OH coupled to its detection by laser-induced fluorescence (PLP-LIF). More than eighty determinations of k5 were carried out in nitrogen or air bath gas at various temperatures and pressures. The accuracy of the rate coefficients obtained was enhanced by in-situ measurement of the concentrations of both HNO3 reactant and NO2 impurity. The rate coefficients show both temperature and pressure dependence with a rapid increase in k5 at low temperatures. The pressure dependence was weak at room temperature but increased significantly at low temperatures. The entire dataset was combined with selected literature values of k5 and parameterised using a combination of pressure dependent and independent terms to give an expression that covers the relevant pressure and temperature range for the atmosphere. A global model, using the new parameterisation for k5 rather than those presently accepted, indicated small but significant latitude and altitude dependent changes in the HNO3 / NOx ratio of between −6 % and +6 %. Effective HNO3 absorption cross sections (184.95 and 213.86 nm, units of cm2 molecule−1) were obtained as part of this work: σ213.86 = 4.52+0.23−0.12 × 10−19 and σ184.95 = 1.61+0.08−0.04 × 10−17.

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