In-situ catalytic pyrolysis upgradation of microalgae into hydrocarbon rich bio-oil: Effects of nitrogen and carbon dioxide environment.

Pyrolysis of Spirulina Platensis (SP) microalgae was carried out under different reaction environment such as nitrogen (N2) and carbon dioxide (CO2) at different reaction temperatures of 300, 350, 400, 450 and 500 °C. Catalytic upgradations were examined over solid acid (ZSM-5) and solid base (MgO) catalyst, and with ZSM-5-MgO catalysts mixtures. Results showed, pyrolysis of non-catalytic biomass yielded maximum bio-oil of 43.6% under N2. However catalytic upgradation in CO2 environment produced lower bio-oil due to the coke formation. Maximum bio-oil (46.2 wt%) was obtained with basic metal MgO catalyst in N2 environment compared to other catalyst and environments. Mixture of MgO-ZSM-5 catalyst improved the bio-oil yield (37.8-48.6 wt%) compared to individual catalytic reaction under N2 and CO2. Higher high heating value (HHV) was observed in catalytic bio-oil 36.8 MJ/Kg. Bio-oil (catalytic) analysis revealed that 64-70% of compounds are in hydrocarbon range. Bio-oil was rich in hydrocarbons of C7-C18 range with less oxygenated compounds.