Ozonolysis reactions have been intensively investigated due to their importance in many branches of chemistry such as synthetic organic, atmospheric, and combustion, but the mechanistic details are not fully understood in part due to limitations in detecting intermediate species. In particular, ozone addition is considered a promising method to enhance and control combustion and ignition processes. Mass spectrometric methods and synchrotron-based techniques are used here to selectively study individual processes involved in the ozone assisted oxidation reaction of trans-2-butene in a temperature range between 300 and 900 K. An atmospheric pressure jet stirred reactor in conjunction with a high-resolution tunable synchrotron photoionization time-of-flight mass spectrometer is used to monitor the chemical transformations of key intermediates via identification and quantification of previously elusive intermediate species. A significant trans-2-butene oxidation is observed upon ozone addition in the low-temperature range between 300 and 600 K. A variety of multi-functional peroxide species are identified based on the experimentally measured photoionization spectra and <i>ab initio</i> threshold energy calculations for isomer identification. A reaction network of Criegee intermediates (CIs) is identified, which is described by the addition of CIs to species like trans-2-butene, water, and formaldehyde. Detection of additional oxygenated species such as methanol, ketene, aldehyde, and acetoin suggest multiple active oxidation routes. These findings improve our understanding of ozone assisted oxidation reaction of alkenes at ambient and elevated temperature conditions providing a database for future modeling.

Mechanistic understanding of ozone assisted low-temperature oxidation rection of trans-2-butene in a jet stirred reactor

ACS Spring Meeting 2021

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