In-depth analyses of kinetics, thermodynamics and solid reaction mechanism for pyrolysis of hazardous petroleum sludge based on isoconversional models for its energy potential

Abstract

The pyrolysis of hazardous petroleum sludge (PS) has widely been used for its remediation and energy extraction. However, in view of process optimization, scale-up, design and simulation, the kinetic (activation energy and frequency factor) and thermodynamic parameters (change in enthalpy ( Δ H), entropy ( Δ S), and Gibb's free energy ( Δ G)) along with reaction mechanism followed by pyrolysis has rarely been investigated. Therefore, pyrolysis of PS was investigated in thermogravimetric analyzer (TGA) at three heating rates viz. 5, 10, 15 K min−1. The kinetic and thermodynamic parameters were estimated by iso-conversional methods such as Kissinger-Akahira-Sunose (KAS), Starink and Ozawa-Wall- Flynn (OWF) method. Further, solid reaction mechanism during pyrolysis was examined by employing Criado method (Z-master plot). The effect of heating rate on thermodynamic parameters and solid reaction mechanism was also examined. The average activation energy using Starink method was found to be 76.77 kJ mol−1. The frequency factor, Δ H, Δ S and Δ G at 5 K min−1, using activation energy from Starink method was found to be 3.23 × 107 sec-1, 70.78 kJ mol−1, -0.168 J mol-1 K-1, and 189.88 kJ mol−1, respectively. Z-master plot revealed that solid reaction mechanism depend on the degree of conversion and heating rate during pyrolysis of PS. © 2020 Institution of Chemical Engineers