Measuring biomass fast pyrolysis kinetics: State of the art

摘要

Fast pyrolysis of lignocellulosic biomass is considered to be a promising thermochemicalroute for the production of drop-in fuels and valuable chemicals. Duringthe past decades, a comprehensive understanding of feedstock structure, fast pyrolysiskinetics, product distribution, and transport effects that govern the process hasallowed to design better pyrolysis reactors and/or catalysts. A variety of lignocellulosicbiomass feedstocks, like corn stover, pinewood, poplar, and model compoundslike glucose, xylan, monolignols have been utilized to study the thermaldecomposition at or close to fast pyrolysis conditions. Significant progress hasbeen made in understanding the kinetics by developing unique setups such as droptube,PHASR, and micropyrolyzer reactors in combination with the use ofadvanced analytical techniques such as comprehensive gas and liquid chromatography(GC, LC) with time-of-flight mass spectrometer (TOF-MS). This has led to initialintrinsic kinetic models for biomass and its main components, namelycellulose, hemicellulose, and lignin, validated using experimental setups where theeffects of heat and mass transfer on the performance of the process, expressedusing Biot and pyrolysis numbers, are adequately negligible. Yet, not all aspects offast pyrolysis kinetics of biomass components are equally well understood. The useof time-resolved or multiplexed experimental techniques can further improve ourunderstanding of reaction intermediates and their corresponding kinetic mechanisms.The novel experimental data combined with first principles based multiscalemodels can reshape biomass pyrolysis models and transform biomass fast pyrolysisto a more selective and energy efficient process.