Time-Resolved Fast Pyrolysis Using a Free-Fall Reactor and a Time-of-Flight Mass Spectrometer

Time resolved fast pyrolysis was investigated using a Time-of-Flight Mass Spectrometer  (TOF-MS) integrated with a Free-Fall Reactor. Sampling ports along the axis of the vertically oriented reactor provided spatially resolved measurement of chemical species according to molecular weight.  Spatially resolved data was converted to time resolved concentration based on free-fall velocities of the pyrolyzing biomass. In some cases it was possible to assign molecular weights to specific molecular species although for most lignin-derived compounds this was not possible.  This presentation focuses on the anhydrosugar levoglucosan, which is easy to identify from the MS data and has a relatively well-known reaction pathway, although little is known about the kinetics of its formation.  The time-resolved data for levoglucosan is used to estimate reaction rates for its formation from cellulose. The effects of reactor temperature, sweep gas velocity, and biomass-to-sweep gas ratio are evaluated.