Control of the fate of toxic pollutants from catalytic pyrolysis of polyurethane by oxidation using CO2

Abstract

In automotive industry, plastic consumption has substantially increased due to its affordability, durability, and lightness. However, the massive generation of plastic wastes from the automotive industry becomes a growing environmental concern. Current disposal methods of end-of-life vehicles (ELVs) are incineration and landfilling, but these methods generate toxic chemicals and leachate into the environment. To propose more sustainable disposal platform for ELVs, this study used a pyrolysis process using CO2 as a reaction medium. As a case study, automotive seat form (ASF) in ELVs was disposed and valorized through the CO2-assisted pyrolysis. ASF, composed of polyurethane, generated harmful aromatic compounds during pyrolysis process such as benzene, aniline and their derivatives. To convert harmful chemicals into value-added syngas (H2 and CO), catalytic pyrolysis of ASF was performed using a nickel catalyst. Effects of both CO2 and nickel catalyst showed 89.9 wt% reduction of toxic chemical production by converting them into syngas, as comparing to pyrolysis without Ni catalyst. Gas-phase-reaction between CO2 and pyrogenic products from ASF resulted in more than 200 times of CO production. Also, CO2 suppressed catalyst deactivation. Therefore, this study suggested that CO2 and plastic waste from ELVs can be converted to value-added products through CO2-assisted catalytic pyrolysis.