Fast pyrolysis of Saccharina japonica alga in a fixed-bed reactor for bio-oil production

Highlights: • Fas pyrolysis of Saccharina japonica was conducted in a fixed-bed reactor. • Effects of pyrolysis temperature and sweeping-gas flow rate were investigated. • The highest liquid yield was obtained at the temperature in range of 350–500 °C with a sweeping gas flow rate of 300 ml/min. • The HHVs of pyrolysis bio-oils from S. japonica were in the range of 32.97–33.26 MJ/kg. - Abstract: Macro-algae are recognized as a potential feedstock for renewable energy and fuel production. Saccharina japonica is a kind of macro-algae that has been extensively cultivated in Korea. Through pyrolysis, S. japonica can be converted into bio-oil, gas, and char. In this study, we investigated the fast pyrolysis of S. japonica in a fixed-bed reactor at different temperatures from 350 to 550 °C with sweeping-gas flow rates of 100, 300, and 500 ml/min. As the pyrolysis temperature was increased from 350 °C to 500 °C, the bio-oil yields decreased while the gas yields increased. The highest liquid yield (40.91 wt%) was obtained at a pyrolysis temperature of 350 °C with a sweeping-gas velocity of 300 ml/min. The major compositions in the bio-oil were di-anhydromannitol (34.45%), iso-sorbide (19.84%), and 2-methyl furyl ketone (8.43%). The gas products (including CO, CO₂, H₂, and hydrocarbon gases from C₁ to C₄), were analyzed by gas chromatography with an FID and a TCD. The bio-chars contained a high carbonaceous content can be used as a pollution-free solid fuel or for the production of activated carbon and other chemicals.