Hydrogen-rich syngas production and tar removal from biomass gasification using sacrificial tyre pyrolysis char

- Tyre char is used as catalyst and syngas source in pyrolysis-reforming of biomass.
- Metals in tyre char catalyse tar decomposition.
- Increased steam and higher temperature promotes H2 production.
- Syngas H2/CO ratio varied between 1.3 to 2.
- A waste derived catalyst degrades tar and is also sacrificed for char gasification.

Carbonaceous materials have been proven to have a high catalytic activity for tar removal from the syngas produced from biomass gasification. The simultaneous reforming and gasification of pyrolysis gases and char could have a significant role in increasing the gas yield and decreasing the tar in the product syngas. This study investigates the use of tyre char as a catalyst for H2-rich syngas production and tar reduction during the pyrolysis-reforming of biomass using a two stage fixed bed reactor. The biomass sample was pyrolysed under nitrogen at a pyrolysis temperature of 500 °C, the evolved pyrolysis volatiles were passed to a second stage with steam and the gases were reformed in the presence of tyre char as catalyst. The influence of catalyst bed temperature, steam to biomass ratio, reaction time and tyre ash metals were investigated. The influence of the catalytic activity of tyre ash minerals on composition of syngas and tar decomposition during the steam reforming of biomass was significant as the removal of minerals led to a decrease in the H2 yield. Raising the steam injection rate and reforming temperature resulted in an increase in H2 production as steam reforming and char gasification reactions were enhanced. The maximum H2 content in the product syngas of 56 vol.% was obtained at a reforming temperature of 900 °C and with a steam to biomass mass ratio of 6 (g/g). Further investigation of the influence of the biomass:steam ratio on syngas quality showed that the H2:CO molar ratio was increased from 1.8 (steam: biomass ratio; 1.82 g g−1) to 3 (steam: biomass ratio; 6 g g−1).

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