Pyrolysis of plastic waste into fuel : an experimental study of polyethylene pyrolysis

Abstract

Plastic waste is an increasing economic and environmental problem as such there is a great need to process this waste and reduce its environmental impact. In this research the pyrolysis of high density polyethylene (HDPE) waste products is investigated using both thermal and catalytic cracking techniques. The experimental work is carried out in a laboratory scale packed bed reactor operating under an inert atmosphere at a temperature of 450ºC. Different reactor beds, including sand, cement and white clay are used in the reactor to enhance the thermal cracking of HDPE. In addition, the catalytic effect of sodium hydroxide, HUSY and HBeta zeolite catalysts on the degradation of HDPE waste is inspected; the liquid products obtained from the pyrolysis experiments were analyzed using GC-MS to identify composition and product distribution. Varyingthe reactor bedmaterial greatly altered the yield as well as the composition of the generated products. The highest yield of liquid (82percent) was obtained over cement reactor bed with alkane composition of 57.6percent. The carbon chain length was narrowed to C₁₀-C₂₈ when the zeolitic catalysts were employed, as well as a significant yield of aromatics was obtained mainly naphthalene and D-Limonene as an indication that products obtained are fuel-like products. Sand-HUSY and Cement HUSY produced the highest composition of alkanes of 80.8percent and 60.8percent respectively.