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

C.A Nwadinigwe,T.N Alumona,A.M Lawal,N Surma,C.C Ezeofor

doi:10.4314/jasem.v22i6.18

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 C 1 – C 10 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 C 1 – C 10 aliphatic hydrocarbons which can be fractionated into fuel gases (C 1 – C 4 ), gasoline range gases (˃C 7 ) and organic solvents (C 5 – C 7 ). Keywords: Pyrolysis, high density polyethylene, zeolite, aliphatic hydrocarbon

Highlights

Ethylene, with crude oil and natural gas as precursors, is one of the six major petrochemical industrial raw materials
This work focuses on low temperature pyrolysis of post-consumer high density polyethylene wastes in other to recovery fuel gases from them
The weight obtained at the end of the pyrolysis reaction was 900 g while 110 g and 120 g were obtained at the end of the catalytic pyrolysis at catalyst/sample ratios of 1:8 and 1:16 respectively

Summary

Introduction

With crude oil and natural gas as precursors, is one of the six major petrochemical industrial raw materials. It can be polymerized into high or low density (HDPE or LDPE) polyethylenes. These differ slightly in molecular structure depending on operating conditions, pressure. Both HDPE and LDPE are thermoplastic, tough with a slightly waxy feel, and widely used for the manufacture of domestic wax, bottles, packing films and all kinds of industrial components using various methods of moulding. Loss of hydrogen atom followed by hemolytic β -fission of a C- C bond could be a possible pathway, Nwadinigwe, (2012)

Methods

Results

Conclusion