Combustion Chemistry of Cyclic Ether Radicals

Oxidation of hydrocarbons is comprised of a series of chemical reactions that are in constant competition based on the conditions of the reaction environment. Further understanding of these pathways and the implications of this competition is important to improving the efficiency of combustion systems used for transportation. To calculate the contribution of each reaction, quantification of the intermediates formed must be conducted. However, these intermediates either have a short lifespan or are formed from various complex reaction networks. One example is through pathways mediated by hydroperoxy-substituted carbon-centered radicals (QOOH). The clearest identifiers for these reactions are a class of species called cyclic ethers. However, consumption reactions of cyclic ethers are oversimplified in combustion models. In the present work, experiments and potential energy surface computations were conducted on alkyl-substituted oxiranes that are cyclic ether products from n-butane. At the Advanced Light Source of Lawrence Berkeley National Laboratory, Multiplexed Photoionization Mass Spectrometry (MPIMS) was used to properly characterize and quantify the consumption reactions for these intermediates. The outcome from this work provides a foundation into further studies for cyclic ethers, and how these pathways will affect our understanding of combustion schemes.