Fast pyrolysis of macroalga Saccharina japonica in a bubbling fluidized-bed reactor for bio-oil production

• Fast pyrolysis of Saccharina japonica was conducted in a bubbling fluidized-bed reactor.
• Effects of pyrolysis temperature and fluidization velocity were investigated.
• The highest bio-oil yield of 44.99% was obtained at the pyrolysis temperature of 350 °C.
• The HHVs of pyrolysis bio-oils from S. japonica were in the range of 24.75–28.72 MJ/kg.

Macroalgae have recently attracted attention as a possible feedstock for bio-fuels. Saccharina japonica, a kind of macroalgae, can be converted into bio-oil, gas, and char through pyrolysis. In this study, fast pyrolysis of Saccharina japonica was performed in a bubbling fluidized-bed reactor under various conditions. The effects of pyrolysis temperature and fluidization velocity on product yield and the quality of bio-oil were systematically investigated. When the pyrolysis temperature increased from 350 °C to 500 °C, the bio-oil yield steadily decreased from 44.99 wt% to 26.67 wt%. The major compounds in the bio-oil were di-anhydromannitol and 2-methyl furyl ketone, showing the highest selectivities of 24.08% and 17.18%, respectively. The 13C NMR results showed that shorter aliphatic carbon and lower molecular weight compounds of alcohols, ketone, and their derivatives were generated during pyrolysis at higher temperatures due to secondary decomposition reactions. This research showed the feasibility of converting macroalgae biomass into bio-oil by fast pyrolysis.