Environmental pollution and greenhouse
gas emissions are major
challenges faced by our society. One possible way to mitigate global
warming is to cut CO2 emissions by taking a shift from
conventional fuels to renewable fuels for future sustainability. Carbon
neutral fuels produced in a sustainable carbon cycle can close the
carbon cycle and reach net zero-carbon emission. To this end, ethers
are promising renewable fuels and/or additives for future advanced
combustion engines. Therefore, understanding the oxidation behavior
of ethers under engine-relevant conditions is of utmost importance.
In this work, the reaction kinetics of hydroxyl radicals with dimethyl
ether (DME), diethyl ether (DEE), di-n-propyl ether
(DPE), and di-n-butyl ether (DBE) were investigated
behind reflected shock waves over the temperature range of 865–1381
K and the pressure range of 0.96–5.56 bar using a shock tube
and a UV laser diagnostic technique. Hydroxyl radicals were monitored
near 306.7 nm to follow the reaction kinetics. These reactions did
not exhibit discernible pressure effects. The temperature dependence
of the measured rate coefficients can be expressed by the following
modified Arrhenius equations in units of cm3 mol–1 s–1: k
1(DME+OH) =
1.19 × 1014 exp(−2469.8/T), k
2(DEE+OH) = 1.27 × 107
T
2 exp(327.8/T), k
3(DPE+OH) = 1.64 × 107
T
2 exp(368.4/T), k
4(DBE+OH) = 9.12 × 1011
T
0.65 exp(−843.5/T). Our measured rate data were analyzed to obtain site-specific
rates and branching ratios. Our results are compared with the available
literature data wherever applicable. Furthermore, the ability of Atkinson’s
structure–activity relationship (SAR) to predict the kinetic
behavior of the reactions of dialkyl ethers with OH radicals was examined.
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