The effect of inorganic impurities on CO2 gasification of a spent tyre pyrolysis char

This paper reports an experimental study of the effect of the inorganic impurities on the CO2 gasification of a spent tyre pyrolysis char. The raw char was washed with 1M HCl at 24°C for 24h with subsequent multiple 2h 1M HCl washes to ensure the removal of inorganic impurities including ZnO, ZnS and CaSO4. Both the raw and acid-washed pyrolysis chars were gasified under a CO2/N2 atmosphere (66.7% CO2) for 3h in a fixed-bed reactor at 850, 950 and 1050 °C, respectively. The burn-off was calculated and the BET surface area was characterised. It was found that the raw pyrolysis char showed higher burn-off than the acid-washed pyrolysis char, indicating that the inorganic impurities promoted gasification. The raw pyrolysis char exhibited higher BET surface area at 850 and 950 °C, and lower surface area at 1050 °C than the acid-washed char.