Pyrolysis characteristics and kinetics of waste photovoltaic module: A TG-MS-FTIR study

The emerging application of solar power plants has led to serious waste photovoltaic module disposal problems. To address the environmental concerns associated with waste photovoltaic module disposal, this study investigates pyrolysis as a promising treatment technology and a fundamental step for various thermal chemical processes. The kinetic characteristics and pyrolysis products of ethylene vinyl acetate (EVA), Tedlar-Polyethylene Terephalate-Tedlar (TPT), and silica gel were studied using TG-FTIR-MS. The weight loss stages of EVA, TPT, and silica gel were between 300 and 510 °C, 330–520 °C, and 100–830 °C, respectively, with a total weight loss rate of 99–100%, 73–76%, and 60–62%. The reactions they experienced were acetic acid production and long chain fracture, long chain fracture and fluorocarbon compound production, polymer methyl vibration, [(CH3)2SiO] cyclic compound production, Si–C bond fracture, and CO2 production, respectively. According to the results of the two kinetic models, their average activation energies were 278-281 kJ/mol, 330-336 kJ/mol, and 187-193 kJ/mol. The products released during the pyrolysis process of the three samples were different. Among them, olefins and aromatic hydrocarbons from EVA and TPT could be used to synthesize high-molecular-weight substances. Aldehydes, fats, and esters from TPT could be used to synthesize drugs and daily necessities; hydrofluoric acid and furan were harmful to human health and the environment. Hexamethylcyclotrisiloxane and octamethylcyclotetrasiloxane from silica gel could be used to synthesize silicone polymers. The content of volatile substances during pyrolysis was related to the heating rate. The findings are expected to contribute to the development of waste photovoltaic module disposal and resource recovery through pyrolysis.