Biofuels are increasingly being viewed as a promising alternative fuel resource due to the growing concerns about increasing global energy consumption and the effects of growing carbon dioxide emissions from fossil fuels. Pyrolysis has been reported as one of the economic ways (i.e., low capital and operating costs) to utilize biomass for bio-fuels and bio-chemicals. However, the produced pyrolysis oils always have higher oxygen content, molecular weight, viscosity and acidity than gasoline and diesel, and consequently they are characterized as having thermal instability, corrosiveness, poor volatility, low heating value, high coking tendency, immiscible with petroleum fuels, and one of the most challenging property -- aging problem. It is well known that the viscosity of pyrolysis oils increases with storage of time, especially when the oils are stored or handled at high temperature. The average molecular weight of pyrolysis oils also increases during the storage and it has been indicated that the formation of larger molecules is one of the reason for the increasing viscosity of pyrolysis oils during the storage. Compared to the well known properties include viscosity, water content and molecular weight of aged pyrolysis oils, only a few of researchers have characterized aged pyrolysis oils primarily by FT-IR and GC/MS to identify changes in chemical structures. Our previous work employed in-situ NMR to monitor the aging process of various pyrolysis oils; however, due to the complexity of pyrolysis oil, the detailed aging mechanisms are still unknown. To explore the mechanisms of aging process is a crucial topic for both development of catalysts and evaluation of upgraded pyrolysis oils. In this study, the fundamental study for the aging process of several pyrolysis oil model compounds has been investigated. The in-situ monitoring of aging process for the cross linking reactions of several model compound have also been examined. The concepts established in this work provide new insights into the aging process of pyrolysis oil.

Aging process of biomass pyrolysis oil and its model compounds � a mechanistic study

248th National Meeting (2014)

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