Stable Bio-oil Production from Proteinaceous Cyanobacteria: Tail Gas Reactive Pyrolysis of Spirulina

Pyrolysis of spirulina, a cyanobacteria with high levels of protein (74 wt %) and low levels of lipid (0.8 wt %) content, has the potential to produce fuels and platform chemicals that differ from those produced from lignocellulosic materials. The yields and product distribution from fluidized-bed pyrolysis of spirulina using the U.S. Department of Agriculture - Agricultural Research Service's tail gas reactive pyrolysis (TGRP) process were evaluated and compared with those produced under an inert atmosphere. Important differences include improved performance of the system when using TGRP along with lower viscosity (77.6-148.5 cP at 27 degrees C) and higher energy content (32.5-33.5 MJ/kg) of the bio-oil compared to conventionally produced liquids. Chemically, the TGRP bio-oils were composed largely of aromatic hydrocarbons, phenols, and nitrogenated compounds. This more stable mixture allowed for distillation of the bio-oil into fractions with higher concentrations of certain platform chemicals including phenolics and nitrogenated compounds such as pyrrole. In addition to the liquid, the biochar and noncondensable gases had improved properties.