Effect of metal content on CO₂ gasification behavior of K- and Fe-loaded bio-chars

Abstract

The effects of Fe and K contents of Fe- and K-loaded chars containing 0-23% Fe and 0-20% K, respectively, with negligible amounts of poisoning elements, on the CO₂ gasification behavior (C + CO₂ → 2CO) were investigated in the temperature range of 750-1050°C. For 23% Fe-loaded char at gasification temperatures of 900 and 1000 °C, the CO₂ gasification rate constants (K_p) were respectively 3.3 times and ～ 8 times higher than those of the char without Fe. At 900 °C, the K_p value increased with an increase in the Fe content up to 10% and remained almost constant above 10% Fe. For K-loaded chars, the K_p value of the char loaded with 10% K had a maximum value of 5.4 min⁻¹at 900 °C; this value was ～ 300 times that of the char without K loading and ～ 90 times higher than the corresponding K_p values of Fe-loaded chars at 900 °C. The addition of excess K (upon loading greater than 10%) to bio-char decreased the K_p because of the decrease in the number of active sites on the char surface.