Unraveling the hydrocracking capabilities of fluidized bed systems operated with natural ores as bed materials

Abstract

Hydrocracking represents an alternative to the recycling of abundantly available plastic waste. Hydrocracking of polyethylene in a fluidized bed, at 750 °C and 1 atm, was investigated in this work. Water dissociation, through the steam-iron reaction, was used as the source of hydrogen. Bauxite and olivine, containing reduced iron, were used as the bed materials in the reactor to drive the water dissociation reaction. The hydrogen-to-carbon (H/C) ratios of the products were compared to assess the hydrocracking potential. It was discovered that conversion of polyethylene on the surface of reduced bauxite effectively increased the H/C ratios of the products, as compared to bauxite in its oxidized form. Reduced olivine was ineffective at increasing the H/C ratios of the products in the presence of water dissociation. It is concluded that hydrocracking through hydrogen donation by steam is feasible in fluidized beds, provided that the bed material has the ability to transfer the hydrogen atoms to the hydrocarbon species.