Abstract

Terpenes are a class of hydrocarbon compounds naturally found in plants. They already have a variety of uses, such as flavor and fragrance additives. Also, they can be blended with conventional or synthetic liquid fuels. Understanding the kinetics of terpenes combustion is important for the development of cleaner combustion, as well as for evaluating associated air pollution and environmental impacts. Therefore, the oxidation of terpenes has been performed under well-controlled conditions. The cool flame oxidation of limonene, α-pinene, and β-pinene, terpenes commonly emitted by vegetation, was performed in a jet-stirred reactor under fuel-lean conditions, at 1 bar. Samples of the reacting mixtures were collected, dissolved in acetonitrile, and analyzed by high-resolution mass spectrometry. Direct flow injection and chromatographic separation by ultra-high-performance liquid chromatography were used. Heated electrospray ionization and atmospheric pressure chemical ionization were employed to characterize the products of oxidation. H/D exchange using D2O was performed for probing the presence of hydroxyl and hydroperoxyl groups in the products. The Brady reaction was used to assess the presence of carbonyl functional groups in the products. A large set of oxidation products, including highly oxidized organic products with 5 and more oxygen atoms, was observed. Besides, FTIR analyzes of gas products were performed. Aromatic and/or polyunsaturated products were detected. Graphic tools including Van Krevelen plots, aromaticity index, and maximum carbonyl ratio, and Venn plots were used to analyze the results. Reaction pathways are proposed to rationalize the results.

This content is only available via PDF.
You do not currently have access to this content.