Complete inhibition of char formation from cellulose in fast pyrolysis with aromatic substance

Aromatic substances stabilize levoglucosan and other monomeric glycosides by solvation against thermal decomposition including char formation. We applied this stabilization to inhibit char formation from cellulose, a crystalline polysaccharide. Cellulose was heated with various types of aromatic substances in a heating mantle (slow pyrolysis) or by inserting a sample in a ceramic boat into a furnace preheated to 700 degrees C under a nitrogen flow (fast pyrolysis). As a result, only fast pyrolysis in aromatic substances with polar substituents (>C=O or -N=) and high boiling points >400 degrees C completely inhibited the char formation. By the NMR analysis, the major product was identified to be levoglucosan (LG), and the selectivity increased in the presence of aromatic substances probably due to the stabilization of LG in the molten products produced from cellulose fast pyrolysis. The phscicochemical properties required for aromatic substance are discussed with the nature of the cellulose crystallite surface and its decomposition temperature. (C) 2016 Elsevier B.V. All rights reserved.