Pyrolysis of low-density polyethylene

Abstract

Pyrolysis of low-density polyethylene in an innovative batch pilot plant, with a hydraulic guard ensuring a safe process, was performed. The influence of process temperature on yield, distribution and composition of products was investigated. The oil/waxes were analyzed by gas chromatography coupled mass spectrometry, while pyrolysis gas was monitored online during the process by micro-gas chromatography. Pyrolysis were carried out at 450, 500, 550 and 600 °C. Results obtained show that low temperatures yield a greater amount of oil/waxes, and a gas enriched in carbon oxides and C3+ hydrocarbons. At higher temperatures, the gas fraction, riche in methane and hydrogen, is predominant over liquid products. This process has proved to be a versatile way to recover polyethylene wastes into valuable oils (rich in aliphatic and simple aromatic hydrocarbons) or gas, to be used as petrochemical feedstock or fuel, thus providing a sustainable method for material and energy recovery of waste packaging.