Effect of pressure and biomass ashes addition on the steam gasification of tire char

This work aims to assess the effect of pressure on steam gasification of tire char catalysed by 10 and 15 wt% of biomass ashes (sunflower husk, beet pulp, beech chips, corn cobs). The gasification measurements were performed in quasi-isothermal conditions (800–900 °C) at pressures of 0.5 and 1 MPa, using the thermovolumetric method. The obtained data allowed the determination of conversion degree curves, reactivity indexes, yields of the main gaseous components, and kinetic parameters of the conversion reaction. Pressure increases favour carbon-steam reaction during non-catalytic gasification of tire char, but at higher conversion degrees, the process slowed down. In turn, the combination of the influence of pressure increase and catalyst addition eliminated the slowing down effect, and resulted in higher conversion degrees and CO yields, while the H₂ yields decreased. However, the positive effect of catalytic gasification compared to the non-catalytic process was observed only in the low-temperature range, 800–850 °C. In summary, pressure increase improves the catalytic conversion of tire char (especially while using 15 wt% of sunflower husk ash at 850 °C), but if the process is aimed at obtaining hydrogen, it should be carried out at lower pressure (especially while using 15 wt% of corn cobs ash at 800 °C).