Nature and Properties of Intermediate and Unvaporized Biomass Pyrolysis Materials

    Research output: Chapter in Book/Report/Conference proceedingChapter

    Abstract

    Many types of chemical pathways aimed at representing the primary process of biomass degradation have been published. These models include or ignore the possibility of the existence of an intermediate 'Active' species or state. The purpose of this paper is to gather theoretical results and experimental observations intended to open the discussion on the possible existence and nature of such anintermediate. The results of the modelling of the chemical and thermal behavior of biomass undergoing a pyrolysis decomposition are first given. Simple experimental and visual observations associated with theoretical considerations based on heat transfer measurements lead then to the conclusion that the overall reaction is similar to a fusion sith production of an intermediate liquid species.From kinetic rate constants derived from literature, it appears that it is not necessary to take into account such a liquid in thermogravimetric analysis (TGA) experiments, but that it cannot be ignored in high temperature ablative pyrolysis conditions. At the end of the paper, a discussion is conducted on the possible chemical natures of these liquids, the evolved vapours and the condensedpyrolysis oils formed in a pyrolysis process. It is concluded that the primary liquids could be composed of dimers and higher oligomers derived from cellulose and lignin, while the vapours would be mainly monomers and monomer fragments from the cracking of oligomers in the liquid phase.
    Original languageAmerican English
    Title of host publicationDevelopments in Thermochemical Biomass Conversion
    EditorsA. V. Bridgwater, D. G. B. Boocock
    PagesVol. I: 27-42
    DOIs
    StatePublished - 1997

    NREL Publication Number

    • NREL/CH-431-20970

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