Speaker
Description
To understand the thermal decomposition mechanisms of fuels, we are developing a tiny flow tube to study the thermal cracking of complex organic molecules. We use a heated 1 mm × 2 cm SiC microtubular reactor to decompose complex fuels. Thermal decomposition of 0.1 % samples mixed with He or Ar carrier gases takes place at pressures of 75 — 250 Torr and at temperatures up to 1700 K. Residence time of the organics in the reactor is roughly 25 — 150 µsec. The pyrolysis products are identified by several independent techniques: VUV photoionization mass spectroscopy, resonance enhanced multiphoton ionization, microwave spectroscopy, and matrix-isolated, infrared absorption spectroscopy.
Aromatics (toluene, xylenes, alkylbenzenes, etc.) make up roughly ¼ of all aviation fuels. Thermal cracking of these fuels produces a pool of "persistent“ radicals. We have observed radical/radical reactions to produce benzene and naphthalene. These are early steps in the formation of "soot“.
CH$_3$ + C$_5$H$_5$ → C$_6$H$_6$ (benzene) + 2 H atoms
C$_5$H$_5$ + C$_5$H$_5$ → C$_{10}$H$_8$ (naphthalene) + 2 H atoms
