Production of Liquid Fuels from Discarded Pure Water Sachets: Effect of Catalyst Loading on the Amount of Liquid Produced

Abstract

Only a small fraction of end-of-life ‘pure’ water sachets (PWS) is currently recycled in Ghana, with the rest being illegally discarded. In this work we investigate the potential for producing liquid fuel (diesel) from shredded PWS in a custom-made pyrolytic equipment using a ternary mixture of Al₂O₃-SiO₂-Fe₂O₃ (generated locally) as catalyst. Samples of PWS sourced locally from the University of Mines and Technology, Tarkwa, were dried in air and shredded into small pieces using a pair of scissors. The shredded pieces were fed into a reactor that also served as catalytic cracking chamber. Varying amounts of the catalyst were added to the shredded mass followed by heating to temperatures ranging from 300-500 °C after which the resulting gaseous hydrocarbon mixture was condensed into liquid in a measuring cylinder that serves as a condenser. Physical properties like colour, density and flashpoint of samples of the liquid produced were determined and compared to conventional liquid fuels. It was observed that limited amount of liquid was generated in the absence of the catalyst; the amount of liquid produced showed a dramatic increase in the presence of the catalyst and it increased progressively with the amount of catalyst loaded into the cracking chamber. At temperatures below 350 °C in the catalytic chamber the condensed liquid turned waxy over time, suggesting poor catalytic cracking of long chain hydrocarbons. The waxy appearance disappeared when temperatures in the catalytic chamber exceeded 350 °C. Whilst the colour appeared closer to the colour of diesel, the density and flashpoint appeared in range that corresponded to those of diesel and kerosene. We conclude that liquid fuel production is a potential route for diverting end-of-life plastics from landfill sites.