Urban mining of fuel gases via low temperature pyrolysis of post-consumer high density polyethylene wastes

Abstract

Low temperature pyrolysis of high density polyethylene (HDPE) wastes was studied by adapting a cylindrical pressure cooking pot of height 30.00 cm with an internal diameter of 31.50 cm. The pyrolysis reaction was carried out with and without catalysts. The gases evolved during the pyrolysis were collected in Tedlar bags and analysis was done using a Buck 530 Gas chromatograph. Results when the pyrolysis was without catalyst, showed aliphatic hydrocarbons in the range of C₁ – C₁₀ with a total concentration of 87.0114 ppm and 93.9733 ppm at 200ºC and 350ºC respectively. The pyrolysis was repeated under catalytic influence of zeolite using catalyst/sample ratios of 1:8 and 1:16 at 150 ºC and 250 ºC. Results showed that the total yield of gases for HDPE under the zeolitic effect at temperatures of 150 ºC and 250 ºC using catalyst/sample ratio of 1:8 to be 159.4613 ppm and 394.4499 ppm respectively. The corresponding values obtained at 150 ºC and 250 ºC using catalyst/sample ratio of 1:16 were 595.8016 ppm and 724.0983 ppm respectively. The hydrocarbon gases revealed C₁ – C₁₀ aliphatic hydrocarbons which can be fractionated into fuel gases (C₁ – C₄), gasoline range gases (˃C₇) and organic solvents (C₅ – C₇).

Keywords: Pyrolysis, high density polyethylene, zeolite, aliphatic hydrocarbon