Compositional analysis of bio-oil derived from pyrolysis of seaweed

► The major components of seaweed bio-oil are hydrocarbon, ketones, aldehydes, etc. ► The constituents of seaweed bio-oil are different from that of land-based bio-oil. ► The hydrocarbon matters generate in seaweed oil due to carbohydrates and lipids. ► The generation of the nitrogen compounds in seaweed oil is due to protein. The pyrolysis of two seaweed (Enteromorpha clathrata and Sargassum natans) was investigated for the production of bio-oil under different conditions. The constituents of seaweed bio-oils were greatly different from those of terrestrial biomass, especially in the presence of many nitrogen-containing compounds. Besides nitrogen-containing compounds, major components of seaweed bio-oil were hydrocarbon, ketones, aldehydes, alcohols, and phenolic compounds, as well as carboxylic acids and their derivatives. It was found from the comparison between two bio-oils that E. clathrata bio-oil had lots of hydrocarbons, carboxylic acids and their derivatives, however S. natans bio-oil contains many steroids and alcohols compounds. In addition, the oleic acid, palmitate, and peanut acid were also detected in S. natans bio-oil. Pyrolysis temperature played an important role on the distribution of seaweed bio-oil compositions, while the influence of the carrier gas was not obvious. The liquid derived from pyrolysis of protein contained more than 50% nitrogen-containing organic compounds, few phenolic compounds and aldehydes. It was concluded that the generations of hydrocarbon matters in seaweed bio-oil were associated with carbohydrates and lipids, and the nitrogen compounds were in accordance with protein.