On the mechanism of the rapid pyrolysis of cellulose

Experimental yields and liquid product analyses obtained from the fast pyrolysis of biomass and cellulose in a fluidized bed reactor have been used to demonstrate that the decomposition of cellulose to liquid products proceeds to a major degree by a single mechanism. At temperatures over about 450°C and at vapor residence times of one second or less, it is proposed that the monomer unit of cellulose decomposes preferentially to a two-carbon and a four-carbon fragment, with the two-carbon fragment rearranging to give a yield of hydroxyacetaldehyde (glycolaldehyde) which is 75% or more of that theoretically probable. The most likely route for decomposition or rearrangement of the four-carbon moiety is suggested. The formation of carbonyl or hydroxycarbonyl compounds with two to four carbon atoms is favored. Experimental results from the fast pyrolysis of poplar wood indicate that the cellulose decomposition in wood follows the same path as that of pure cellulose in the production of liquid products.