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

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 hydrocarbo

Assessment of n-alkanes and acyclic isoprenoids (geochemical markers) in crudes: A case study of Iraq and Niger delta, Nigeria

This study was designed to determine the ratios of the isoprenoids and n-alkanes in an imported crude oil sample (Bassrah from Iraq) and four crude oil samples (Bodo, Bonny-Export, Escravos and Penningston) from the Niger Delta region of Nigeria to ascertain the levels of maturity and as an indicator of the depositional environment of the crudes. The physical properties of the crudes: viscosity, density and °API gravity were also determined. Fractionation of the crudes was done using a new approach coded NAASAR, (n-alkanes, asphaltenes, aromatics and resins) comprising urea adduction followed by gas chromatographic analyses (for n-alkanes), n-heptane precipitation (for asphaltenes) and column chromatography (for resins). Results showed °API gravities Bassrah 28.03°, Bodo 31.89°, Bonny-Export 33.8°, Escravos 33.8°, and Penningston 33.8° indicating that Escravos, Penningston and Bonny-Export crudes are light crudes while Bodo and Bassrah crudes are medium crudes. The n-alkanes profiles of the five crudes were determined by gas chromatography ranged from n-C8H18 to n-C40H82 with total weight percent n-alkane yield Bassrah 11.2, Bodo 47.41, Bonny-Export 32.47, Escravos 5.58, Penningston 30.75 were obtained by urea adduction. The pristane to phytane ratios were computed, Bassrah 1.51, Bodo 1.48, Bonny-Export 1.08, Escravos 1.01 and Penningston 2.41. Isoprenoids to n-alkane ratios Pr/n-C17 in the same order of the crudes were 0.85, 0.83, 0.67, 0.65, 0.95 while phytane to n-C18 ratios were 0.61, 0.55, 0.62, 0.61 and 0.43. The results established the increasing level of maturity as obtained from Pr/n-C17 ratio in the order: Penningston < Bassrah < Bodo < Bonny-Export < Escravos. The result of Pr/Ph ratios show the same trend in the level of maturity. Penningston crude with Pr/Ph ratio 2.41 shows that the crude is deposited in fluviomarine and coastal swamp environment while Bassrah, Bodo, Bonny-Export and Escravos crudes indicate aquatic depositional environment (anoxia) condition. Keywords: Assessment, n-Alkanes, Acyclic isoprenoids, Pristane, Phytane, Maturit