Particle size impact on pyrolysis of multi-biomass: a solid-state reaction modeling study

ABSTRACT

Pyrolysis has gained significant attention due to its generation of value-added products from waste feeds in an environmentally friendly manner. The primary purpose of this study is to understand the effect of different particle sizes of biomass wastes – date stones (DS), cow manure (CM), and spent coffee grounds (SCG) – to understand better and design a biomass pyrolysis system. Thermogravimetric analysis of four different sizes of DS, SCG, and CM (range 1 mm to 125 μm) and a mixed sample (for each feed) was conducted at a heating rate of 10K/min from room temperature to 1173.15 K at inert conditions and employed model-based Coats–Redfern equations to understand the kinetic and thermodynamic parameters of the pyrolysis process. All the particle sizes except 355–125 μm for DS and SCG have the best-fit reaction mechanism of Ginstling-Brounshtein (D4). Both activation energy and pre-exponential factor decreased from 18.78 to 5.57 kJ/mol and 1.16 E+10 to 1.48 E+08 with reducing particle sizes. The onset degradation temperature, activation energy, change in enthalpy, and entropy decrease with particle sizes. The product formation is favored for all feeds and particle sizes, as the difference between the enthalpy and activation energies (Ea) is below 10 kJ/mol. As a result of their substantially lower activation energies and better reaction thermodynamics, mixed and smaller particle-sized biomass are favored.

KEYWORDS:

• Pyrolysis
• TGA
• kinetics
• coats-redfern
• thermodynamics
• particle size

Acknowledgements

Open Access funding provided by the Qatar National Library.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author, S.M., upon reasonable request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2023.2196945

Additional information

Funding

This publication was made possible by NPRP – Standard (NPRP-S) 11 cycle grant - NPRP11S-0117-180328 from the Qatar National Research Fund (a member of the Qatar Foundation). The findings herein reflect the work and are solely the responsibility of the authors.

Notes on contributors

Sabah Mariyam

Sabah Mariyam is a Ph.D. candidate in the Division of Sustainable Development at Hamad Bin Khalifa University (HBKU) in Qatar. Her research interests are focused on sustainable energy processes, with a particular emphasis on waste-to-energy generation using thermochemical processes like pyrolysis. Sabah has published several works in her field, including empirical prediction modeling of products, multi-biomass pyrolysis kinetics and thermodynamics, and product characterization. Through her research, she aims to develop innovative solutions for sustainable energy generation that can contribute to a cleaner, more sustainable future for all.

Tareq Al-Ansari

Dr. Tareq Al-Ansari acquired a BEng. in Mechanical Engineering from the University College of London and an MPhil. in Engineering for Sustainable Development from the University of Cambridge and completed his Ph.D. at Imperial College London in Sustainable Development and Environmental Engineering. Currently, he is an Associate Professor at the College of Science and Engineering at HBKU within the Division of Sustainable Development, where he is the division head.

Gordon McKay

Professor McKay has almost four decades of experience in academia and industry. He is presently a Professor of Sustainable Development at Hamad Bin Khalifa University. He has held previous positions at the Hong Kong University of Science and Technology (HKUST) as Head of the Department and Professor of Chemical and Biomolecular Engineering. Before his academic career, he spent 10 years in industry and established his own company, Consultancy Process Engineering and Management Systems, which was later subcontracted to Foster Wheeler, Ireland. Professor McKay has authored eight books, over 800 publications in international refereed journals, and co-authored the third most cited paper in the SCI Chemical Engineering sector.