Conversion of Solid Wastes to Fuel Energy Resources through Normal and Catalytic Pyrolysis Process Conditions: A Renewable Resources Strategy

Abstract

This paper presents findings of a study on solid wastes conversion into fuels through pyrolysis of plastic materials, presenting an alternative renewable approach for waste management. Investigations were conducted on conversion of polypropylene (PP), low-density polyethylene (LDPE) and high-density polyethylene (HDPE) under normal and catalyst mediated process conditions. Plastic wastes were collected from various dumpsites in Nairobi and segregated using plastic resin codes to various classes. Samples were cleaned, dried and shredded to 2 mm and fed into a pyrolysis reactor. The pyrolysis process was conducted at between 220˚C and 420˚C. Pyrolysis gases were condensed in a shell and coil condenser and the incondensable gases were stored in gasbags. Liquid fuels were analysed using Gas chromatograph with a mass spectroscopic detector and Fourier Transform Infrared Spectrometry. The results revealed that the most optimal process conditions were a temperature range of 220˚C - 420˚C at a heating rate of 10˚C per minute. Under these conditions, the oil yields were 53.72% for PP, 62.10% for LDPE, and 64.14% for HDPE. As the heating rate increased from 10˚C/min to 20˚C/min, gas yields increased, rising from 28.05% to 31.12% in PP, 14.96% to 30.62% in LDPE, and 18.51% to 29.49% in HDPE. The introduction of Fe 2 O 3 and Al 2 O 3 catalyst significantly enhanced gas production during pyrolysis, increasing yields from 18% to 61% and 47% respectively.