Torrefaction of Switchgrass As a Pretreatment for Catalytic Upgrading of Pyrolysis

The objective of this work is to use thermal pretreatment to separate the complex bio-oil mixture to produce less complex vapor streams of products from 1. light oxygenates (small aldehydes, acids) , 2. furan derivatives, and 3. phenolics. The selective production of products by thermal treatment is beneficial for catalytic upgrading of bio-oil vapors since different types of products require different catalytic upgrading and would be the first stage of a multi-stage pyrolysis process. Thus more selective and stable catalysts can increase the yields of desired products and lower the cost. In this study, torrefaction of switchgrass has been carried out at various temperatures lower than that for fast pyrolysis (500^oC). Because biomass components, including cellulose, hemicellulose and lignin, break down over different temperature ranges, the enrichment of the product vapors to focus their composition by controlling their evolution may be achieved efficiently.