辅助活化法制备超级活性炭的机理

Preparation of high surface area activated carbons by KOH activation promoted by alkali metal halides

采用辅助活化法合成了大比表面、孔隙结构发达的超级活性炭。详细考察了碱金属和碱土金属的卤化物在活化过程中的辅助活化作用,并利用快速中止反应技术探索了辅助活化机理。结果表明:助活化剂中阳离子的半径及还原后相应金属的还原能力强烈影响着活性炭的孔分布;而阴离子的存在起到调变电子助剂的作用,能够提高活化中心的活化能力。在低温活化段助活化剂主要促进了孔口的扩张,而中、高温活化段推动了径向活化过程。

The role of different alkali and alkali-earth metal halides in the preparation of high surface area activated carbons by KOH activation was investigated. The samples were quickly quenched after activation temperature and time was reached. Results indicated that pore size distribution of the high surface area activated carbons was strongly affected by the diameter of the metal cation and reduction activity of the metal. The anion acted as electron donor to increase the activity of active sites. Surface etching to expand micropore openings occurred at low activation temperature and in-depth etching was preferred at high activation temperature.