Kinetics, reaction models, and thermodynamic feasibility of non-isothermal catalytic pyrolysis of <i>Erythrina indica</i>

The pyrolysis process, which involves the transformation of biomass into valuable products like bio-oil, biochar, and non-condensable gases, is a crucial aspect of biomass waste utilization. Gaining an insight into the kinetics and thermodynamics involved in this process is paramount for enhancing its efficiency. This research employs iso-conversional methods to study the kinetics of non-catalytic and catalytic pyrolysis of Erythrina indica (EI) biomass at four different heating rates followed by thermodynamic feasibility. The catalytic pyrolysis of biomass was studied using 10 wt. % of catalysts such as biochar (obtained by non-catalytic pyrolysis of EI at 800 °C for 2 h), nickel, and titanium dioxide for each case to evaluate their effects on kinetics and thermodynamics. The iso-conversional methods include the differential Friedman method, Ozawa–Flynn–Wall, Kissinger–Akharia–Sunose, distributed activation energy model, and Starink. All kinetic models showed strong agreement (R2 &amp;gt; 0.96). The reaction models were also evaluated using the integral form of the master plots and were compared with those by Criado's master plots approach. Biochar catalyst exhibited the lowest activation energy requirements (155.924–162.846 kJ/mol), followed by titanium dioxide (160.231–167.924 kJ/mol) and nickel (172.125–176.482 kJ/mol), while non-catalytic pyrolysis required the highest energy (176.861–184.784 kJ/mol) for EI pyrolysis. Thermodynamic analysis revealed that biochar catalytic pyrolysis required the lowest enthalpy change (ΔH: 156–160 kJ/mol), followed by titanium dioxide (160–168 kJ/mol) and nickel (174–177 kJ/mol), all lower than non-catalytic pyrolysis (176–186 kJ/mol). The Gibbs free energy (ΔG) remained similar (170–175 kJ/mol) across all cases, indicating the conditional feasibility of pyrolysis regardless of the catalyst used. Finally, on the basis of master plots, suitable reaction models were proposed for catalytic pyrolysis of EI biomass.