Hydrogen production from the pyrolysis–gasification of waste tyres with a nickel/cerium catalyst

Abstract

Hydrogen production from the pyrolysis–gasification of waste tyres has been investigated with a Ni/CeO 2/Al 2O 3 catalyst using a two-stage fixed bed reaction system. The conditions of catalyst preparation such as Ni and CeO 2 content and calcination temperature were investigated in relation to product yield and composition. The fresh and reacted catalysts were analysed using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results showed that there were small changes in the gas and hydrogen yield by adding 5 wt.% of CeO 2 into the Ni/CeO 2/Al 2O 3 catalyst. The gas yield related to the mass of waste tyre and the amount of reacted water were increased with the increase of CeO 2 content from 5 to 15 wt.%. However, with the further increase of CeO 2 content to 30 wt.%, the gas yield related to the mass of tyre and the amount of reacted water was reduced. Increasing the Ni content of the catalyst showed a positive influence on the gas yield and hydrogen production. The investigation of the calcination temperature of the Ni/CeO 2/Al 2O 3 catalyst showed that the oil yield related to the mass of tyre and reacted water decreased from 28.4 to 23.4 wt.% for the catalyst calcined at 500 °C, and decreased from 24.2 to 17.7 wt.% for the catalyst calcined at 750 °C. When the Ni content of the catalyst was increased from 5 to 20 wt.%. there were only small changes in total gas and hydrogen production from the pyrolysis–gasification of waste tyre. Lower coke deposition on the reacted catalyst was obtained for the Ni/CeO 2/Al 2O 3 catalyst prepared at the calcination temperature of 750 °C compared with the 500 °C calcination temperature.