Optimization of process parameters for conventional pyrolysis of algal biomass into bio–oil and bio–char production

Abstract

The current study involves the conventional pyrolysis of algal biomass under a batch fixed–bed reactor for the analysis of temperature, retention time, N2 flow rate on pyrolysis product yields Response Surface Methodology by Box–Behnken Design method was used for obtaining optimum parameters. The operating conditions were varied in the range of 450–575 °C, 30–60 min and 0.1–0.5 l/min, respectively. The regression model with 95% confidence level resulted in the high value of R2=98.42% with R2 adjusted=95.59% indicating excellent fit of the data to the model. A maximum yield of 20.1% (organic) + 20.62% (aqueous) by weight of bio–oil obtained at a pyrolysis temperature 575 °C, retention time 45 min and N2 flow rate 0.5 l/min. The Fourier transform infrared analysis study represents a reduction in the quantities of O–H (hydroxyl), CH (alkanes), CO (esters), CH (alkenes), and CO (primary alcohol) groups, under algal biomass at the expanding pyrolysis temperatures. The gas chromatography–mass spectroscopy investigation showed highest concentrations of 4–Methylpentanamide, n–Heptadecane, 2–Methyl naphthalene and n–Hexadecanoic acids in bio–oil.