ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Thermo-catalytic pyrolysis of sawdust by a synthesized NiO/Al₂O₃ composite catalyst: investigation on its reaction mechanism, kinetics, and thermodynamics

Munmi Bhattacharyya, Krushna Prasad Shadangi, Pinakeswar Mahanta, and Kaustubha Mohanty

School of Energy Science and Engineering, Indian Institute of Technology Guwahati, Guwahati, India

E-mail: kmohanty@iitg.ac.in

Received: 20 September 2022  Accepted: 8 April 2023

Abstract:

The study reveals the effect of catalysts on the thermal degradation of sawdust where Ni-based catalysts were used (prepared by wetness impregnation method). The catalyst was prepared at 10% and 20% Ni loading onto the alumina-support by impregnating metallic precursor (Ni (NO₃)₂.6H₂O). The prepared catalyst was characterized using various analytical techniques and observed that it was a composite of NiO and Ni(II) aluminates having a particle size in the range of nano scale. Thermo-catalytic degradation analysis of the sawdust was evaluated by varying the catalyst loading (5%, 10%, 15%, and 20% by weight) at a single heating rate (20 K min⁻¹) within 303–1173 K temperature. Based on the degradability of the catalyst, the effect of the heating rate was perceived. The Kissinger-Akahira-Sunose (KAS) method was followed to observe the degradation kinetics and thermodynamics at every 5% increase in the conversion beyond the evaporation zone. The use of a catalyst during thermal degradation displayed less variation in the activation energy within 65% conversion compared to the thermal. However, a significant variation in the activation energy was observed within 65–95% conversion. The positive value of Gibb’s free energy confirmed the requirement of more energy during thermal compared to catalytic pyrolysis.

Keywords: Pyrolysis; Composite catalyst; KAS method; Kinetics; Thermodynamics; Reaction mechanism

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02826-z

Chemical Papers 77 (9) 4877–4903 (2023)