CHEMICAL ACTIVATION OF COALS USING ALKALI -METAL HYDROXIDES, OXIDES AND CARBONATES

The preparation of active carbons is described, starting from two coal s originating from Freyming and Oignies. Various hydroxides, oxides an d alkali carbonates were used but the originality of this study is the use of cesium derivatives. The interpretation of the CO2 adsorption i sotherms shows clear differences among the various reagents. It is see n that CsOH is more efficient than KOH, and that Cs2O is even more act ive than CsOH. Furthermore, by mixing an inactive hydroxide (NaOH) wit h KOH, a new, more efficient, activating agent was obtained. Immersion calorimetry studies confirm the gas adsorption results. Finally, scan ning electron microscopy and scanning tunnelling microscopy evidence t he formation of porosity.