Chemical Kinetics – Fundamentals and Applications in Atmospheric and Combustion Chemistry

Shock tubes are quite universal tools to study high-temperature reactions in the gas phase (800 K < T < 3000 K). A gas mixture is rapidly (t < 1 μs) heated by a travelling shock wave, and species formed behind the shock front are time-resolved detected, where we use absorption spectroscopy [1] and mass spectrometry. [2] Kinetic data are inferred from the concentration-time profiles. A recent example from our research is the reaction between H atoms and 2,5-dimethylfuran (25DMF), a potential biofuel [1]. The H + fuel reaction is important for the ignition behavior of any fuel, because it competes with the chain-branching step H + O2 OH + O. We studied H + 25DMF, using the reaction sequence C2H5I C2H5 + I C2H4 + H + I to produce H atoms. Concentration-time profiles of H atoms were determined by recording the absorption of the Lyman line. The experimental setup with a microwave discharge lamp as a light source is shown in Fig. 1, and a typical concentration-time profile is displayed in Fig. 2. The rate coefficient is obtained from a fit to the curve. Quantum chemistry and statistical rate theory is then used to characterize the different product channels [1, 2]. In a similar manner we study high-temperature reactions of other oxygenated species [3] and the kinetics of early chemical steps in soot formation [2]. Chemical Kinetics – Fundamentals and Applications in Atmospheric and Combustion Chemistry Prof. Dr. Matthias Olzmann | Institute of Physical Chemistry, Molecular Physical Chemistry