Investigation of Pyrolysis of Hydrocarbons and Biomass Model Compounds Using a Micropyrolysis Flow Cell

Hydrocarbon growth mechanisms based on a combination of small hydrocarbon fragments, such as C2/C4, have been postulated in high-temperature flames. However, there is considerable evidence of alternative pathways, especially in lower temperature regimes, in particular, the importance of resonance-stabilized radicals based on cyclopentadienyl (CPDyl) moieties. Further evidence of polycyclic aromatic hydrocarbon (PAH) growth mechanisms can be provided by analytical pyrolysis experiments using high-temperature flow cells. An analytical micropyrolysis flow cell method has been developed, enabling reactive pyrolysis of solid and liquid samples. This uses a SGE microflow cell pyrojector interfaced to a CDS 5200 series pyrolyzer in adsorbent mode for the product concentration, followed by gas chromatography–mass spectrometry (GC–MS) or Fourier transform infrared (FTIR) analysis. The flow cell system enables residence time and stoichiometry to be varied. The benefits of the system over a filament pyrolyzer are demonstrated. A number of applications of this technique are presented to illustrate the potential of this system to investigate biofuel decomposition, PAH growth mechanisms, and soot formation from different hydrocarbon and oxygenated fuels. Evidence is obtained indicating that resonance-stabilized intermediates, especially CPDyl, are important in PAH growth mechanisms for a wide range of fuel types.