Pyrolysis of coffee residues, tobacco, and algae biomasses as a source of nitrogen-containing compounds

Agro-industrial residues hold immense potential as sustainable energy and bioproduct sources. Thermoconversion through pyrolysis, which generates bio-oil, is a promising approach that simultaneously reduces environmental impact and adds value to biomass. Notably, biomasses with high nitrogen content yield bio-oils rich in diverse, industrially valuable nitrogen-containing compounds (N-compounds). This study investigates the rapid pyrolysis of five such biomasses: spent coffee grounds (SCG), silverskin (SVK), microalgae (MIA), macroalgae (MAA), and tobacco (TBC). A pretreatment step was employed to reduce fat content and enhance bio-oil quality. Gas chromatography analysis subsequently identified the generated N-compounds. The bio-oils revealed a significant presence of oxygenated compounds and hydrocarbons beside N-compounds. The use of Principal Component Analysis (PCA) effectively allowed to group the samples based on their bio-oil compositions, highlighting microalgae as the richest source of N-compounds, particularly after fat pre-extraction.