Chemical and physical insights into castor shell pyrolysis: Composition, blending, and utilization perspectives

The study investigates the fast pyrolysis of unutilized castor shells (CS) as a sustainable and efficient route for bio-oil production. Thermogravimetric Analysis (TGA) was performed at a heating rate of 10 °C/min under a nitrogen atmosphere (50 mL/min) from room temperature to 800 °C to investigate the thermal degradation behavior of the castor shells. Kinetic parameters — activation energy (E), pre-exponential factor (A), and reaction order (n) — were determined using the Coats-Redfern and Direct Arrhenius methods. A lab-scale experiment using a fixed-bed reactor was conducted under the same conditions as the TGA analysis, yielding 27 % bio-oil. Comprehensive characterization of the bio-oil and biogas through GC-MS revealed that 52.08 % of the bio-oil consisted of phenol and phenolic derivatives, indicating its potential for value-added chemical recovery. In a novel approach, the fuel properties of the bio-oil were assessed before and after blending with 10 % methanol, revealing that methanol addition significantly improved the stability of the bio-oil without adversely affecting key fuel characteristics. By integrating kinetic analysis, detailed chemical profiling and robust insights into the pyrolytic reaction mechanisms, this work provides a comprehensive framework for valorizing castor shell biomass, addressing critical gaps in existing pyrolysis research.