2017

A shock tube study of C4–C6 straight chain alkenes+ OH reactions

A shock tube study of C4–C6 straight chain alkenes+ OH reactions

F. Khaled, J. Badra, A. Farooq

Proceedings of the Combustion Institute 36 (1), 289-298, 2017
F. Khaled, J. Badra, A. Farooq
Alkenes, Hydroxyl radicals, Rate coefficients, Shock tube
2017


Alkenes are known to be good octane boosters and they are major components of commercial fuels. Detailed theoretical calculations and direct kinetic measurements of elementary reactions of alkenes with combustion radicals are scarce for C4 alkenes and they are practically absent for C5 and larger alkenes. The overall rate coefficients for the reaction of OH radical with 1-butene (CH2=CH-CH2-CH3, kI), 1-pentene (CH2=CH-CH2-CH2-CH3,kII), cis/trans 2-pentene (CH3-CH=CH-CH2-CH3, kIII and kIV), 1-hexene (CH2=CH-CH2-CH2-CH2-CH3, kv) and cis/trans 2-hexene (CH3- CH=CH-CH2-CH2-CH3, kVI and kVII ) were measured behind reflected shock waves over the temperature range of 833-1377K and pressures near 1.5atm. The reaction progress was followed by measuring mole fraction of OH radicals near 306.7nm using UV laser absorption technique. It is found that the rate coefficients of OH+trans-2-alkenes are larger than those of OH+cis-2-alkenes, followed by OH+1-alkenes. The derived Arrhenius expressions for the overall rate coefficients (in cm3.mol-1.s-1) are: 

kI=(4.83±0.03)104.T2.72±0.01.exp(940.8±2.9cal/mol/RT) (946K-1256K) 
kII=(5.66±0.54)10-1.T4.14±0.80.exp(4334±227cal/molRT) (875K-1379K)
kIII=(3.25±0.12)104.T2.76±0.5.exp(1962±83cal/molRT) (877K-1336K)
kIV=(3.42±0.09)104.T2.76±0.5.exp(1995±59cal/molRT) (833K-1265K)
kV=(7.65±0.58)10-4.T5±1.exp(5840±175cal/molRT) (836K-1387K)
kVI=(2.58±0.06)106.T2.17±0.37.exp(1461±55cal/molRT) (891K-1357K)
kVII=(3.08±0.05)106.T2.18±0.37.exp(1317±38cal/molRT) (881K-1377K) 
 
DOI: 10.1016/j.proci.2016.06.029