Citation: Vitale, A.; Papa, A.A.; Iannello, S.; Ciro, E.; Hatunoglu, A.; Corradetti, V.; Rovelli, N.; Foscolo, P.U.; Di Carlo, A. Devolatilization of Polypropylene Particles in Fluidized Bed. Energies 2023, 16, 6324. https://doi.org/10.3390/en16176324 Academic Editor: Fernando Rubiera González Received: 26 June 2023 Revised: 31 July 2023 Accepted: 18 August 2023 Published: 31 August 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). energies Article Devolatilization of Polypropylene Particles in Fluidized Bed Armando Vitale 1 , Alessandro Antonio Papa 1, * , Stefano Iannello 2 , Erwin Ciro 3 , Arda Hatunoglu 4 , Valerio Corradetti 5 , Nicola Rovelli 5 , Pier Ugo Foscolo 1 and Andrea Di Carlo 1 1 Industrial Engineering Department, University of L’Aquila, Piazzale E. Pontieri 1, Monteluco di Roio, 67100 L’Aquila, Italy; armando.vitale@graduate.univaq.it (A.V.); pierugo.foscolo@univaq.it (P.U.F.); andrea.dicarlo1@univaq.it (A.D.C.) 2 Department of Chemical Engineering, University College London, London WC1E 7JE, UK; stefano.iannello.18@ucl.ac.uk 3 Department of Engineering Sciences, Università degli Studi Guglielmo Marconi, 00193 Rome, Italy; e.ciro@lab.unimarconi.it 4 Department of Astronautics, Electrical and Energy Engineering, Sapienza Università di Roma, Via Eudossiana 18, 00184 Rome, Italy; a.hatunoglu@lab.unimarconi.it 5 ENERECO Spa, Via L. Einaudi, 84/88, 61032 Fano, Italy; valerio.corradetti@enereco.com (V.C.); nicola.rovelli@enereco.com (N.R.) * Correspondence: alessandroantonio.papa@univaq.it Abstract: Gasification of plastic waste is an emerging technology of particular interest to the scientific world given the production of a hydrogen-rich gas from waste material. Devolatilization is a first step thermochemical decomposition process which is crucial in determining the quality of the gas in the whole gasification process. The devolatilization of polypropylene (a key compound of plastic waste) has been investigated experimentally in a bench-scale fluidized bed reactor. Experimental tests were carried out by varying two key parameters of the process—the size of the polypropylene spheres (8–12 mm) and temperature (650–850 ◦ C). Temperature shows the highest influence on the process. Greater molecular cracking results were more pronounced at higher temperatures, increasing the production of light hydrocarbons along with the formation of solid carbon residue and tar. The overall syngas output reduced, while the H 2 content increased. Furthermore, a pseudo-first-order kinetic model was developed to describe the devolatilization process (E app = 11.8 kJ/mol, A 1 = 0.55 s −1 , ψ = 0.77). Keywords: devolatilization; hydrogen; plastic waste; polypropylene; kinetic model; fluidized bed reactor 1. Introduction In recent years, research efforts on renewable and sustainable energy sources have been increasingly intensified due to the complexity of the global energy problems and the urgency of current global warming problems [1]. The world population is projected to increase to over 11 billion people by the end of the 21st century, geographically concen- trated in the developing regions of the world [2]. This will result in net economic growth of those regions, which in the future will cause global growth of energy demand and resource consumption resulting in waste generation [3]. The projected growth of the world population should be compensated by avoiding the current severe mismanagement of waste. In this framework, the European Union (EU) has promoted thematic strategies on waste prevention and recycling, as well as regulations concerning the transition towards a circular and sustainable economy [4,5]. The use of waste as a raw material is crucial in a circular economy for applications in energy and biofuel production, as it is one of the pillars of the 2030 Agenda for sustainable development and contributes to decarbonization and minimization of landfill usage [6]. Based on current power demand and environmental concerns, thermochemical con- versions could be an essential part of a sustainable and integrated waste management Energies 2023, 16, 6324. https://doi.org/10.3390/en16176324 https://www.mdpi.com/journal/energies