Kinetics and thermodynamics of non‐isothermal pyrolysis of Terminalia chebula branches at different heating rates

Abstract

AbstractNon‐isothermal thermogravimetric tests of Terminalia chebula (Helikha) were conducted under inert N2 gas environment for temperatures (25–900°C) at heating rates of 10, 20, 35, and 55°C min−1. Kinetic triplet approximated employing five iso‐conversional methods namely, differential Friedman method (DFM), distributed activation method (DAEM), Ozawa–Flynn–Wall (OFW), Kissinger–Akahira–Sunose (KAS), and Starink (STK). Average values of activation energy (kJ mol−1) and frequency factor (min−1) calculated by the five models were 227.11, 2.98 × 1021 for DFM; 229.21, 4.63 × 1021 for KAS; 227.11, 3.81 × 1020 for OFW; 225.54, 1.15 × 1018 for STK; and 227.33, 3.02 × 1020 for DAEM respectively over the conversion range up to 0.8. In the kinetics study, correlation coefficient (R2) of greater than 0.97 is noticed in the conversion range of α = 0.1–0.8 for all models. From thermodynamic analysis, average values of ΔH (kJ mol−1), ΔG (kJ mol−1), and ΔS (kJ mol−1 K−1) for DAEM: 221.8, 179.69, and 0.065; for DFM: 236.40, 179.37, and 0.089; for KAS: 221.8, 179.69, and 0.065; for OFW: 220.22, 179.72, and 0.063; and for STK: 222.02, 179.68, and 0.066 were estimated to assess viability and reactivity of the process. Criado's master plots revealed that the data obtained from pyrolysis of selected biomass was followed a multistep reaction pathway.