{"title":"Thermodynamic and kinetic analysis of waste plastic pyrolysis: Synergistic effects and sustainability perspectives","authors":"Prathwiraj Meena, Rohidas Bhoi","doi":"10.1016/j.nxsust.2025.100132","DOIUrl":null,"url":null,"abstract":"<div><div>In this study, low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), waste mixed plastics (WMPs) and WMPs with spent fluid catalytic cracking (sFCC) catalyst (WMPs/ sFCC) were investigated to simulate real-life pyrolysis and catalytic pyrolysis of waste plastics using Thermogravimetric analysis (TGA). TGA was performed under different heating rates i.e., 5, 10, 15 and 20 ˚C/min) in an inert nitrogen atmosphere. The pyrolysis kinetics are assessed using three model-free methods, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink, as well as two model-fitting methods, Coats–Redfern (CR) and Criado methods (master plots). The results showed that the WMPs exhibited a positive synergetic effect among the different types of plastics, leading to a notable reduction in degradation temperature and required activation energy. Moreover, adding sFCC catalysts significantly lowered the initial pyrolysis temperature (approximately 47 ˚C) of WMPs compared to direct pyrolysis. Moreover, the average activation energy of WMPs decreased by approximately 13.41 kJ/mole with the inclusion of the sFCC catalyst. The thermodynamic properties such <em>ΔH</em><sup><em>‡</em></sup>, <em>ΔG</em><sup><em>‡</em></sup> and <em>ΔS</em><sup><em>‡</em></sup> suggested that the process was endothermic, non-spontaneous and decreased in randomness during pyrolysis. This study promotes sustainability through a circular economy to convert waste into wealth. These findings offer valuable theoretical insights for reducing energy consumption in plastic pyrolysis and expanding the applications of sFCC catalyst.</div></div>","PeriodicalId":100960,"journal":{"name":"Next Sustainability","volume":"5 ","pages":"Article 100132"},"PeriodicalIF":0.0000,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Next Sustainability","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2949823625000352","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
In this study, low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), waste mixed plastics (WMPs) and WMPs with spent fluid catalytic cracking (sFCC) catalyst (WMPs/ sFCC) were investigated to simulate real-life pyrolysis and catalytic pyrolysis of waste plastics using Thermogravimetric analysis (TGA). TGA was performed under different heating rates i.e., 5, 10, 15 and 20 ˚C/min) in an inert nitrogen atmosphere. The pyrolysis kinetics are assessed using three model-free methods, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink, as well as two model-fitting methods, Coats–Redfern (CR) and Criado methods (master plots). The results showed that the WMPs exhibited a positive synergetic effect among the different types of plastics, leading to a notable reduction in degradation temperature and required activation energy. Moreover, adding sFCC catalysts significantly lowered the initial pyrolysis temperature (approximately 47 ˚C) of WMPs compared to direct pyrolysis. Moreover, the average activation energy of WMPs decreased by approximately 13.41 kJ/mole with the inclusion of the sFCC catalyst. The thermodynamic properties such ΔH‡, ΔG‡ and ΔS‡ suggested that the process was endothermic, non-spontaneous and decreased in randomness during pyrolysis. This study promotes sustainability through a circular economy to convert waste into wealth. These findings offer valuable theoretical insights for reducing energy consumption in plastic pyrolysis and expanding the applications of sFCC catalyst.