AbstractThe physical and chemical properties of raw bio-oil, two oxidized bio-oils, and hydrotreated bio-oil were compared before and after catalytic hydrodeoxygenation using sulfided CoMo/γ-Al2O3 catalyst. Following continuous hydrodeoxygenation, the organic liquid products from treated bio-oils and raw bio-oil were compared for higher heating value, oxygen content, water content, and viscosity. In addition, Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry were employed to identify functional groups and chemical species, respectively. Fresh and spent catalysts were characterized by nitrogen adsorption-desorption for surface area and pore properties. The degree of coking of the spent catalysts was analyzed by thermogravimetric analysis. Hydrodeoxygenation of hydrotreated bio-oil (HB) gave the longest reaction time on stream of 780 min, the least coking amount of 20 wt%, and the highest hydrocarbon selectivity of 70% up to 720 min of reaction time on stream. Moreover, organic liquid products from HB showed relatively stable properties such as low oxygen content, water content, and viscosity over a longer period of reaction time on stream.