碱炭比及活化温度对稻壳活性炭极微孔的影响

采用N₂吸附、CO₂吸附和热重红外联用等技术手段, 考察了在KOH活化稻壳炭的过程中碱炭比和活化温度对活性炭极微孔的影响。结果表明: 在不同碱炭比(0.6︰1~3︰1)和活化温度(640~780℃)下制备的稻壳活性炭, 极微孔主要分布在0.42~0.70 nm。当碱炭比增加时, 极微孔孔容先增大后减小; 而当活化温度升高时, 极微孔孔容呈降低趋势。极微孔率随碱炭比或活化温度的升高而单调递减。在活化温度为640℃、碱炭比为1: 1时, 可得极微孔孔容为0.149 mL/g、极微孔率达36.3%的微孔活性炭。活性炭的极微孔孔容与其在10⁴ Pa时的CO₂吸附量高度线性相关。

Effects of Alkali/Char Ratio and Activation Temperature on Ultramicropores of Rice Husk Active Carbon

Porous carbons were prepared by KOH activation of rice husk char at alkali/char ratios of 0.6︰1 to 3︰1 and activation temperatures from 640℃ to 780 ℃. The obtained porous carbons were characterized using N₂ adsorption and desorption technique, CO₂ adsorption, TG-FTIR analyses. The results indicate that the ultramicropore size of the prepared porous carbons is mostly in the range of 0.42-0.70 nm. As the alkali/char ratio increases, the volume of ultramicropores first rises and then diminishes, whereas the volume of ultramicropores tends to decrease monotonously with the increase of activation temperature. A microporous carbon with ultramicropore volume of 0.149 mL/g, ultramicropore fraction of 36.3%, pore volume of 0.411 mL/g, and specific surface area of 774 m²/g, can be produced by activation at 640℃ at the alkali/char ratio of 1︰1. The ultramicropore volume of the porous carbons and their CO₂ uptake at 10⁴ Pa display a strong linear relationship.