Precursor kinetics and nanoparticle synthesis studied in a shock wave reactor

Abstract

Kineticists all over the world use the shock tube as a high temperature wave reactor for obtaining rate coefficient data under diffusion free conditions, because it provides a nearly one-dimensional flow with practically instantaneous heating of the reactants. The temperature range under which the reactions could be studied can be extended far beyond that of conventional flow reactors. Compared to homogeneous chemical reactions, the study of heterogeneous kinetics is in an early stage. The reasons are that both, the degree of reaction complexity and the difficulties in the diagnostics, are significantly higher. For reactions in dispersed systems, the surface area of the reacting particles needs to be considered, which is experimentally not easy to access. Also, optical absorption diagnostics for measuring concentrations of gaseous species is significantly disturbed by the particles, because of light scattering and light extinction.

In the present paper, some examples of different types of shock wave induced chemical reactions during the synthesis of nanoparticles will be illustrated. Examples are taken from the homogeneous decomposition of iron pentacarbonyl (IPC, FeCOs), the nucleation of iron clusters, and the formation of iron particles.