Pyrolysis of agricultural waste in a thermogravimetric analyzer: Studies of physicochemical properties, kinetics behaviour, and gas compositions

Abstract

Biomass is employed in pyrolysis to generate a substance that can be employed as a feedstock for speciality chemicals as well as a source of energy. Since the oil crisis in the middle of the 1970s, significant progress has been made to transform biomass into liquid fuels and chemicals. To make the process more efficient and optimized, kinetic understanding is required before moving on to applied pyrolysis. Thus, the present study explored the pyrolysis kinetics of low-value agricultural waste biomass at varied heating rates in a thermogravimetric analyzer (TGA). Six model-free methodologies were utilized to analyse the kinetics parameters (Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (FWO), Distributed Activation Energy Model (DAEM), Coats-Redfern (CR), Vyazovkin model (VZ), and master plot). In addition, a TGA-FTIR analyzer was employed to investigate the gas composition online. The physicochemical study’s findings suggested that it could be used as a feedstock for pyrolysis in the bioenergy sector. Furthermore, TGA-FTIR analyzer established the highest discharge of CO2 (28.73 and 33.14 %) and carbonyl products (20.60 and 29.35 %) for WS and CS, respectively. The average apparent activation energies (AAAE) for KAS, OFW, DAEM, and VZ are also determined to be 237.12, 186.40, 170.50, and 163.63 kJ mol−1 for WS and 176.37, 170.51, 196.12, and 194.91 kJ mol−1, for CS respectively. Further, the master plot and thermodynamic study of biomass exposed that pyrolysis passed through many multifaceted reaction mechanisms (Diffusion, nucleation, phase boundary-controlled etc.) during pyrolysis. Overall, pyrolysis techniques can be used to increase the energy density of lignocellulosic residues in an environmentally friendly manner.

Keywords

• Waste Biomass
• Characterization
• Kinetics
• TGA
• TGA-FTIR
• Master Plot