Pyrolysis is a process capable of converting biomass to a liquid bio-oil with a 75wt% yield, which can be further upgraded and blended to create a finished fuel product.  However, raw pyrolysis oil has undesirable properties of high acidity, high oxygen content, instability, and immiscibility with hydrocarbons. One technique to improve the bio-oil quality is the upgrading of pyrolysis vapors, which has been achieved using acidic zeolites, and they have been shown to produce aromatic hydrocarbons that can be condensed to form oils with low oxygen content.  In this study, we have examined the effect of catalyst acidity on distribution of pyrolysis products.  Materials evaluated in this study include ZSM-5 and BEA zeolites of varying silica-to-alumina ratios, and also sulfated and tungstated oxide supports (ZrO2 and Al2O3).  Catalysts were evaluated for their activity for pine pyrolysis at 500�C, and acid properties are investigated using pyridine IR and ammonia TPD.  The zeolite catalysts had a tendency towards the formation of aromatic compounds whereas the sulfated/tungstated ZrO2 and Al2O3 catalysts produced more light gases (e.g., CO, CO2, propane).  Also, the increasingly acidic zeolites had a tendencey towards smaller aromatics (e.g., benzene, toluene) whereas the less acidic zeolites tended towards heavier deoxygenated aromatics (e.g., naphthalene, methyl-naphthalene). The interplay between acid strength and reaction product distribution is discussed.

Upgrading biomass-derived pyrolysis vapors on catalysts of varying acidity

248th National Meeting (2014)

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