Pyrolysis of peanut shell: Kinetic analysis and optimization of thermal degradation process

[Display omitted] •Physico-chemical characterization of peanut shell (PS) biomass of Indian origin.•Thermal degradation studies of PS biomass using TG/DTG analysis.•Kinetic parameters and reaction mechanism using iso-conversional and Criado’s methods.•Pyrolysis in fixed bed reactor and optimization of process parameters using RSM. Thermal degradation kinetics of peanut shell (PS) biomass has been investigated at the heating rates of 10, 15, and 20 °C/min using thermo-gravimetric (TG) and differential thermo-gravimetric (DTG) analyses techniques in the temperature range of ambient to 800 °C. The iso-conversional methods of Flynn-Ozawa-Wall (FOW), Kissinger-Akahira-Sunose (KAS), Starink, Tang, Vyazovkin, and Vyazovkin AIC have yielded activation energy Eα,varying from 186 to 226.97 kJ/mol. Effects of heating rate, temperature and nitrogen gas flow rate on the bio-char and bio-oil yields have been investigated using a fixed bed batch pyrolyser. The Box-Behenken design (BBD) of response surface methodology (RSM) has been used to optimize the process parameters. The average values of bio-oil and bio-char yields at the optimum conditions have been found to be 43.24 and 28.25 %, respectively. The product bio-oil is highly acidic and has the higher heating value (HHV) of 26.49 MJ/kg and the bio-char is rich in micronutrients.