Fuel phase extraction from pyrolytic liquid of Azadirachta indica biomass followed by subsequent characterization of pyrolysis products

Abstract

Growing concerns over fossil fuel utilization and their impending scarcity have spurred a transition towards renewable energy sources. Among these, biomass has gained remarkable traction due to its widespread availability and adaptability. Pyrolysis, amid various biomass conversion routes, boasts advantages like moderate operating conditions, facile handling and efficient product distribution. Nonetheless, the commercialization of pyrolysis faces hurdles. A key challenge involves extracting the fuel phase from raw bio-oil. While numerous studies focus on biomass pyrolysis, comprehensive examinations of fuel phase extraction and subsequent characterization remain limited. Thus, this research concentrates on extracting the fuel phase from pyrolysis oil generated via the lesser-explored Azadirachta indica biomass followed by subsequent characterization. Dichloromethane and n-hexane were the solvents employed at four different volume percentages (10%, 20%, 30% and 40%) as solvents relative to raw bio-oil. The n-hexane emerged as a superior choice based on density, dynamic viscosity, calorific value and selectivity. The pinnacle achievement lies in the fuel phase extracted using 30 and 40 vol. % n-hexane, exhibiting physiochemical comparability to conventional gasoline. For instance, calorific values ranged between 29.1 and 37.1 MJ/kg for n-hexane-extracted fuel phases, compared to 15.1–19.6 MJ/kg for dichloromethane-extracted ones. Fourier-Transform-Infrared spectroscopy unveiled aliphatic compounds, ketones, aromatics, t-butyl compounds, alcohols, hydrocarbons and carboxylic acids. Gas-Chromatography-Mass-Spectroscopy highlighted furan, 2-methoxy- and ethanol, pentamethyl as principal compounds. Energy density of biochar and non-condensable gases stood at 28.5 MJ/kg and 14.9 MJ/Nm3, respectively. Non-condensable gases comprised of 15.9% H2, 26.7% CO, 23.8% CH4 and 33.6% CO2.