Mahua and neem seeds as sustainable renewable resources towards producing clean fuel and chemicals

The aim of the present study is to find out the feasibility of two non-edible oil seeds as a feedstock to produce fuel and value added products using thermochemical conversion technique. Mahua (Madhuca longifolia), and Neem (Azadirachta indica) seeds were characterized based on their characteristics. Kinetic analysis was carried out by using Horowitz and Metzger models. TGA confirmed that maximum degradation occurred in second stage (150–430 °C). Higher calorific value was observed 22.19 MJ kg⁻¹ and 26.88 MJ kg⁻¹ for Mahua and Neem respectively. Further both seed contain higher volatile matter and negligible sulfur content. All the above physicochemical characterization confirmed that these seeds have the potential to produce fuels and chemicals. Kinetic analysis confirmed that the extractive free seeds required higher activation energy to initiate reaction compared to raw seeds. Thermal pyrolysis of both seeds were carried out in a semi-batch reactor at optimized conditions (450 ± 10 °C temperature, 80 °C min⁻¹ heating rate and 80 mL min⁻¹ N₂ flow rate). The yield of pyrolytic liquid was found to be 34.50 and 56.65 wt% for Neem and Mahua seeds respectively. It was found that oil obtained have higher viscosity as well as calorific value which indicated their use as boiler fuel. GC-MS analysis confirmed the presence of valuable chemicals in pyrolytic liquid which may be further purified to obtain pure chemicals. The results of this work is encouraging and affirmed that both these seeds can be excellent renewable resources to produce fuels and chemicals using pyrolysis.