The effects of stabilizing fast pyrolysis oil via catalytic alcohol pretreatment on upgrading via hydrodeoxygenation or thermal treatment was studied by comparing the properties of upgraded-stabilized oils with those of upgraded-non-stabilized oils (benchmarks). The major expected effect was reduction in molar mass of upgraded oils, as stabilization was expected to reduce the reactivity of fast pyrolysis oil, thereby reducing polymerization. It was observed that molar mass reduction was induced by dilution effect of the alcohol rather than reactivity reduction due to stabilization. Also, the effects of different alcohols on stabilization and subsequent upgrading were examined at minimized dilution effect conditions. Stabilization did not significantly affect the molar mass distribution of upgraded oils. However, other properties (e.g. CO2 production and H2 consumption) were significantly affected by stabilization
