Biofuel production via the pyrolysis of sugarcane (Saccharum officinarum L.) leaves: Characterization of the optimal conditions

Abstract

Sugarcane leaves, a lightweight lignocellulosic biomass from a harvested crop, represent a feedstock for in situ pyrolysis to biofuels and valuable chemicals, facilitating the collection and transportation of pyrolyzed oil to industry. In this paper, the pyrolyzed products were separated into water/aqueous and bio-oil fractions, and the yield was characterized. Pyrolysis was performed in a screw-driven custom-built pyrolysis reactor. The effects of pyrolysis parameters, including the temperature (400–650 °C), feedstock feed rate (0.3–1.8 kg h−1), average size distribution (250 µm, 500 µm and 750 µm) and N2 sweeping gas flow rate (80–240 cm3 min−1) were investigated systematically. The results show that the temperature and residence time according to the N2 sweep gas also mainly affects the bio-oil yield and properties such as the acidity, heating value, viscosity and chemical composition, with the highest bio-oil yield (40.16 wt%) obtained at 500 °C, a feed rate of 0.4 kg h−1, an average biomass feedstock particle size of 500 µm, and an inert N2 flow rate of 120 cm3 min−1. Gas chromatography-mass spectrometry analysis of the chemical composition revealed aromatic derivatives, phenols, ketones, and oxygenated compounds of high molecular weight that might be useful chemical products. These results indicate that pyrolyzed oil cannot be utilized as a biofuel directly but instead must be pretreated. The oil should be treated by a co-catalytic pyrolysis process to be considered a potential source for energy and valuable chemicals. In addition, the biochar was analyzed to determine whether it can be used for the production of activated carbon.