关键词: 活性炭, 氧化反应, 初始氧化温度, 自燃温度

Abstract: The SO2 removal technology based on activated carbon or coke could not only solve the pollution problem, but also realize the resource utilization of SO2 in flue gas. However, the exothermic reaction in the process of pollutants removal makes the temperature of activated carbon bed higher than that of flue gas, which is easy to cause accidents. Therefore, it is of great significance to study the oxidation reaction of activated carbon for the safe and reliable operation of the process. Spontaneous ignition temperature (SIT) and point of initial oxidation (PIO) were used to characterize the oxidation process of activated carbon sample. The oxidation reaction of different activated carbon samples was studied by thermogravimetric method in terms of powder sizes, heating rates, oxygen contents, raw material and metal oxides. The results showed that SIT and PIO values obtained by DSC profiles were higher than those obtained by TG profiles， on the whole. For practical operation, it was recommended to use the TG method to evaluate the oxidation reaction of activated carbon. The increase of heating rate would inhibit the oxidation of activated carbon, evidenced by ascending PIO and SIT values simultaneously, and the heating rate had a greater effect on SIT value. While the increase of oxygen content in gas could promote the oxidation, evidenced by descending of both PIO and SIT values with the increase of oxygen content, and the effect of oxygen content on PIO value was more obvious. Activated carbon derived from coal and coconut shell mixture had relatively good oxidation inhibition, and the metal oxides could facilitate the oxidation reaction between coal and coconut shell mixed activated carbon, among which vanadia showed the most significant effect, with PIO and SIT values dropped by 132 ℃ and 139 ℃, respectively.

Key words: activated carbon, oxidation reaction, initial oxidation point, spontaneous ignition temperature