Thermo-catalytic pyrolysis of Azadirachta indica seeds over CaO and CuO: Pyrolysis kinetics, impact of catalysts on yield, fuel properties and its chemical compositions

Pyrolysis oil and distribution is still in the incipient stages, though it is a potential source of energy and valueable chemicals. The current work focused on the kinetics study and thermo-catalytic pyrolysis of Azadirachta indica seeds (AZI) over CaO and CuO. The kinetic behaviour of AZI is studied in a TGA under an inert atmosphere at dynamic heating rates (10, 20 and 30 °C min⁻¹) using Starink method (ST) and Vyazovkin model (VM). Further, AZI were pyrolyzed in a semi-batch tubular reactor at 500 °C, 50 °C min⁻¹ heating rate and 100 mL min⁻¹ nitrogen flow rate at 20 wt% catalyst loading. The biomass and pyrolysis liquid were characterised via proximate analysis, elemental analysis, thermal stability, FTIR, viscosity, density, acidity, moisture content, GC-MS etc. Kinetic analysis of AZIs confirmed that biomass decomposition takes place in a multifaceted route, and the activation energy is associated with conversion and temperature. Thermal pyrolysis exhibited 39.53 wt% liquid yields; however, introducing 20 wt% catalyst has improved the yield to 46.53 wt% and 45.36 wt% for CaO and CuO, respectively. The findings of the thermal and catalytic pyrolytic oil demonstrated that the addition of catalysts significantly enhanced the properties of pyrolytic oil by lowering viscosity and oxygen content while raising heating value and acidity. Finally, GC-MS results displayed that the use of catalysts resulted in a considerable decline in the proportion of oxygenated compounds, acids, and phenols and an increase in the proportion of hydrocarbons, aldehydes and alcohols.