Pyrolysis of Residual Tobacco Seeds: Characterization of Nitrogen Compounds in Bio-oil Using Comprehensive Two-Dimensional Gas Chromatography with Mass Spectrometry Detection

Energetic tobacco (EnT) is a type of genetically modified tobacco with a focus on energy. Its seeds are larger and appear in greater quantity than those of conventional tobacco. This plant easily adapts to unproductive soils and is practically free of nicotine. The oil seed from EnT can be used for producing biodiesel without competition with edible oils. Additionally, the resulting residual cake can be thermally degraded to bio-oil and biochar through pyrolysis processes. In this study, the fast pyrolysis (700 °C at 100 °C min–1) of the residual cake of EnT seeds was performed in a fixed bed reactor (quartz), yielding approximately 40% (in mass) liquid products (bio-oil and an aqueous phase). After removal of the aqueous phase, the organic phase was submitted to an acid–alkaline extraction of the N-compounds in a simple and efficient way. The bio-oil and alkaline extract were analyzed by comprehensive two-dimensional gas chromatography coupled to fast-quadrupole mass spectrometry. Compounds were tentatively identified by similarity with a commercial library of mass spectra and using retention indexes. The main classes of compounds identified were phenols, hydrocarbons, and N-compounds (imidazole, pyridine, and their derivatives), with the potential to be applied in the chemical and pharmaceutical industries as well as biofuel production. The alkaline extraction resulted in the isolation of the main N-components, a finding fundamental for the utilization of these compounds for the production of pharmaceuticals, pesticides, and polymers.