AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
New Explorations into the Atmospheric Auto-oxidation of Volatile Organic Compounds
S. MANI SARATHY, Zhandong Wang, Matti Rissanen, Mikael Ehn, KAUST
Abstract Number: 698 Working Group: Aerosol Chemistry
Abstract The auto-oxidation of volatile organic compounds (VOCs) is of central importance to atmospheric chemistry. In the troposphere, the chemistry of alkylperoxy radicals and their derivatives determines the fate of VOCs. Several studies have shown that auto-oxidation of VOCs under low-NOx conditions leads to the formation of extremely low volatility organic compounds (ELVOCs) that ultimately impact air quality and climate. The mechanistic pathways leading to formation of highly oxidized multifunctional molecules (HOMs), which are the building blocks for ELVOCs, are not well understood. A detailed investigation of the structure of HOMs, their reaction mechanisms, and corresponding kinetics can help develop models to predict the distribution of HOMs and ELVOCs in the atmosphere. We find there are synergies in hydrocarbon auto-oxidation chemistry studied in combustion systems and analogous processes occurring in the atmosphere. These areas are the focus of this proposed exploratory research. We have conducted well-controlled reactor experiments with advanced analytical chemistry diagnostics to study the structure of HOMs produced during the auto-oxidation of various VOCs (alkanes, alkenes, naphthenes, aromatics, etc.). The experiments help us understand the effects of VOC source, temperature, and residence time on the concentration and chemical nature of HOMs that are produced. The results of these studies have enabled us to develop reaction mechanisms that describe the initial destruction of VOCs and subsequent formation of HOMs.