Catalytic pyrolysis of waste thermocol using rice husk ash and zeolite: A sustainable approach for hydrocarbon recovery and renewable fuel production

Abstract

The piling up of waste thermocol (polystyrene) is causing environmental issues due to its non-biodegradable properties. Conventional disposal methods are ineffective, necessitating eco-friendly approaches for degrading waste thermocol (WT) into useful hydrocarbons as alternative fuels. This study investigates the catalytic pyrolysis of WT using rice husk ash (RHC) and zeolite (ZeC) as catalysts. Thermal degradation was conducted at 224–410 °C, yielding 62 % liquid, 21 % gas and 17 % solid residue after 100 min. The catalytic influence of RHC and ZeC was evaluated at a 0.1 catalyst-to-polymer ratio. RHC reduced the degradation temperature to 190–370 °C, increasing liquid yield to 76 % with complete conversion in 80 min. ZeC further lowered the conversion temperature to 170–320 °C, achieving complete degradation in 60 min with a 49 % liquid product and 51 % gas yield. Gas Chromatography-Mass Spectrometry (GC-MS) and Nuclear Magnetic Resonance spectroscopy (NMR) analysis revealed that RHC-derived waste thermocol oil (WTCO) contained both aromatic and aliphatic hydrocarbons, whereas ZeC-derived WTCO was predominantly aromatic hydrocarbons. Both exhibited fuel-like properties, with calorific content and density comparable to diesel. The findings emphasize the importance of catalyst selection in maximizing hydrocarbon recovery, demonstrating waste thermocol's potential as a renewable fuel source.