Insights into the Reactions of Hydroxyl Radical with Diolefins from Atmospheric to Combustion Environments

Abstract

Hydroxyl radicals and olefins are quite important from combustion and atmospheric chemistry standpoint. Large amounts of olefinic compounds are emitted into the earth's atmosphere from both biogenic and anthropogenic sources. Olefins make a significant share in the tranportation fuels (e.g., up to 20% by volume in gasoline), and they appear as important intermediates during hydrocarbon oxidation. As olefins inhibit low-temperature heat release, they have caught some attention for their applicability in future advanced combustion engine technology. Despite their importance, the literature data for the reactions of olefins are quite scarce. In this work, we have measured the rate coefficients for the reaction of hydroxyl radicals (OH) with several diolefins,

Reaction kinetics of 1,4-cyclohexadienes with OH radicals: an experimental and theoretical study

“…The details of the experimental setup and data treatment can be found elsewhere. 20,[22][23][24][25] Only a brief description is provided here. An excimer laser (Lambda Physik LPX 201) at 248 nm was used to photolyze H 2 O 2 generating OH radicals exclusively.…”

Low-Temperature Hypergolic Ignition of 1-Octene with Low Ignition Delay Time

“…The ignition delay times of pure 1-octene and 1-octene/BDMS at various ratios were also determined using the high-speed CCD camera. The OH· could promote the combustion reaction due to the changes in OH· during combustion at 306.5 nm. , This process was recorded with a high-speed CCD camera equipped with an ultraviolet (UV) lens coupled to an image intensifier and a 310 nm optical filter system (optical measurement system), as shown in Figure .…”

Identification of Isoprene Oxidation Reaction Products via Anion Photoelectron Spectroscopy

“…The choices of oxidizing gas mixtures, which generate • OH and ozone, were also motivated by atmospherically relevant reactions of these radicals with isoprene. • OH is the primary tropospheric oxidizer of isoprene, 28,29 and ozone is the second-most prevalent oxidizer of isoprene (although at a much lesser percentage of total isoprene reactions). 28 The reaction of isoprene with • OH accounts for ∼85% of isoprene's reactive fate and contributes to its average atmospheric lifetime of only 1−2 h. 30 The reactions of isoprene and ozone have been more difficult to fully characterize due to uncertainty in kinetic measurements 31,32 and the relatively low percentage of isoprene + ozone reactions out of all isoprene reactions, but isoprene ozonolysis forms a wide variety of products and is a known ozone loss mechanism in areas of high isoprene concentrations.…”

“…• OH is the primary tropospheric oxidizer of isoprene, 28,29 and ozone is the second-most prevalent oxidizer of isoprene (although at a much lesser percentage of total isoprene reactions). 28 The reaction of isoprene with • OH accounts for ∼85% of isoprene's reactive fate and contributes to its average atmospheric lifetime of only 1−2 h. 30 The reactions of isoprene and ozone have been more difficult to fully characterize due to uncertainty in kinetic measurements 31,32 and the relatively low percentage of isoprene + ozone reactions out of all isoprene reactions, but isoprene ozonolysis forms a wide variety of products and is a known ozone loss mechanism in areas of high isoprene concentrations. 33 As such, identifying potential products of these reactions (especially in a high-temperature regime, which could be consistent with the conditions observed in combustion) of both reactions is of significant importance.…”

“…The choices of oxidizing gas mixtures, which generate • OH and ozone, were also motivated by atmospherically relevant reactions of these radicals with isoprene. • OH is the primary tropospheric oxidizer of isoprene, , and ozone is the second-most prevalent oxidizer of isoprene (although at a much lesser percentage of total isoprene reactions) . The reaction of isoprene with • OH accounts for ∼85% of isoprene’s reactive fate and contributes to its average atmospheric lifetime of only 1–2 h .…”