Mechanisms of biomass pyrolysis studied reactor with advanced gas analysis by combining a fixed bed

Slow pyrolysis of different biomasses (miscanthus, douglas fir and oak) was conducted in a U-shape fixed bed reactor combined to (1) on-line analysis of the vapors (primary tar) by soft photoionisation mass spectrometry (single photoionisation time-of-flight mass spectrometer, SPI-TOFMS), (2) quantitative off-line analysis of condensed vapors by GC*GC/MS-FID and (3) permanent gas analysis. The U-shape fixed bed reactor allows controlling external mass transfers, temperature of the bed, quenching char at targeted temperatures and quantifying mass balances. The mass yields in solid, condensable products and gas are studied between 200 degrees C and 500 degrees C. The soft on-line photoionisation analysis leads to a more interpretable mass spectra with few fragment ions and gives the evolution of the main markers of volatiles produced in real-time as a function of the temperature. The chemical structure of the markers analyzed on-line by SPI-TOFMS is assigned by GC*GC/FID-MS analysis. The mechanisms of hemicelluloses, cellulose and lignin pyrolysis in the complex network of biomass (including minerals catalytic effect) are discussed. (C) 2015 Elsevier B.V. All rights reserved.