Bio-oil production from Moringa oleifera Lam. residue through fixed-bed pyrolysis

The thermal degradation of lignocellulosic materials is one of the most promising approaches for obtaining energy sources and chemical products. In this study, the chemical and thermochemical characterization of Moringa oleifera Lam. seeds and residues showed that biomass can potentially be used to produce energy through a thermochemical conversion process. The seeds and biomasses of Moringa oleifera Lam. were submitted to pyrolysis, the main method of thermochemical conversion. Pyrolysis reactions were conducted in a stainless steel fixed-bed reactor under atmospheric nitrogen pressure, temperatures of 500–600 °C and N2 gas flow of 1 and 3 mL min−1. The calorific value of the biomass ranged from 17 to 21 MJ/kg. The results obtained in the optimization of the pyrolysis conditions in a fixed-bed reactor, the temperature of 600 °C, and N2 flow of 1 mL min−1, were selected. The chromatographic analysis (GC/MS) of the bio-oil allowed the identification and semi-quantification of the different chemical classes present in the bio-oils (acids, phenols, oleonitriles, hydrocarbons, aromatics, ketones, aldehydes, ether, amines, amides, alcohol). High content of carboxylic acids (superior values 70%) was observed for the seeds and mechanical residue, and a high content of phenolic and nitrogen compounds, with 43% in both cases, for the Soxhlet residue. The moringa residues can be considered as a productive source of bioproducts, significantly reducing the harmful effects of chemicals originating from fossil fuels, while minimizing the disposal of waste into the environment.