Kinetics of Radical-Radical Reactions in Combustion Chemistry

Catholic University Of America, Washington DC

Investigators

Abstract

0853706 Knyazev The research is directed at determination of the kinetics of radical-radical reactions important in the oxidation and pyrolysis of hydrocarbons. These reactions usually serve as chain termination and molecular-mass growth pathways. Certain members of this class of reactions have been linked to formation of aromatic rings and polyaromatic hydrocarbons, which leads, in turn, to production of soot in combustion systems. In spite of the importance of radical-radical reactions for understanding the chemistry of a wide variety of combustion and pyrolysis processes, experimental information on them is rather sparse and, in many cases, controversial. The main objective of the work is the establishment of a reliable database of accurately determined experimental data on a benchmark set of reactions. The project covers several types of radical-radical reactions, including self-reactions and cross reactions of alkyl, cycloalkyl, and delocalized and aromatic radicals. Temperature dependences of the rate constants are being determined in direct experiments under conditions where radicals are created in known concentrations and the reactions under study are isolated from side influences. Radical concentration decays and formation of products are monitored in real-time using Laser Photolysis / Photoionization Mass Spectrometry technique. Reaction-product studies are performed by online mass spectrometry as well as GC/MS of final products. Results of the study will be of fundamental importance for modeling the combustion of hydrocarbon fuels, forming an experimental basis for further advancement of high-level theories of reaction rates and semi-empirical computational tools. Benefits to society will be advanced by improving our understanding of commercial technologies such as energy generation through combustion, including the safety and environmental aspects of these processes. Other broader impacts of the proposed work will come from integration of education and research and contributions to training and education of undergraduate and graduate students. Broad dissemination of the results will be advanced via publications, presentations in multi-disciplinary conferences and workshops, web presentation of the findings, and contributing to cyberinfrastructure projects.