In this research, dried cabbage, chicken and rice were pre-treated by hydrothermal or pyrolytic carbonizations (HTC or PC). Non-isothermal gasification by thermal gravimetric analyzer (TGA) was conducted to explore gasification behavior of the chars. The maximum gasification rate temperature (Tmax) was used to explain the comparison of the reactivity and higher Tmax means lower reactivity. For cabbage and chicken, higher alkaline index of their PC200 char, with Tmax of 795°C and 910°C respectively, led to higher reactivity compared to their HTC200 chars, with Tmax of 925°C and 992°C respectively. However, the catalytic effect by alkaline was minimized in the case of rice feedstock and the rice PC200 (Tmax of 986°C) showed slightly higher reactivity than HC200 (Tmax of 990°C). Therefore, the higher reactivity of PC chars may not only be correlated with the alkaline index but also with development of the pore structure. Increasing the HTC temperature resulted in a lower alkaline index and thereby lowered the reactivity. However, morphology of the char would be the dominant factor for PC char. Increasing the PC temperature will enhance the stable structure like graphite in the chars, leading to lower reactivity.
Keywords hydrothermal, pyrolytic carbonization, solid structure, gasification reactivity, food waste