Production of Bio-Oil from De-Oiled Karanja (Pongamia pinnata L.) Seed Press Cake Via Pyrolysis: Kinetics and Evaluation of Anthill as the Catalyst

In this study, bio-oil was produced from the pyrolysis of de-oiled karanja seed press cake in the presence of abandoned anthill as the catalyst. The anthill was characterised by SEM, EDX, XRF, XRD and surface area and pore size analysis. The pyrolysis experiments were carried out in an indigenously made furnace in a nitrogen atmosphere from 310 to 400 °C. The pyrolysis oil was collected at an optimised temperature and analysed through gas chromatography–mass spectrometry (GC-MS). The compounds identified via GC-MS of non-catalytic bio-oil were in the range of C5 to C19, and compounds identified from catalytic bio-oil were in the range of C2–C63. Furthermore, thermogravimetric analysis of the karanja seed press cake without and with anthill was carried out in a nitrogen atmosphere with temperature programme rates of 3, 12, 20 and 30 °C·min−1. Kinetic parameters were determined by applying the Kissinger equation. The activation energy (Ea) values for hemicelluloses, cellulose and lignin were obtained as 99.7 ± 0.4, 182.9 ± 0.5 and 199.5 ± 0.7 kJ·mol−1 without catalyst; and with catalyst, the Ea were lowered to 74.8 ± 0.2, 83.1 ± 0.4 and 108.0 ± 0.5 kJ·mol−1, respectively. From the results, it was concluded that the catalyst played a key role in lowering the activation energy for the pyrolysis reaction and enhanced the quality of the bio-oil obtained as well.