Thermodesorption study of first stage graphite FeCl3 intercalation compounds

With the aim of synthesizing carbonaceous materials with specific adsorbent properties obtained from the pyrolysis of mixtures of coal tar pitch (CTP) and FeCl3 graphite intercalation compounds (GIC), we present a study of the thermodesorption of first stage FeCl3 GIC. These GICs were synthesized in a two temperature reactor with several kinds of graphites characterized by different granulometry and crystallinity (one a monocrystalline graphite and the others, polycrystalline). During heating under an inert atmosphere, FeCl3 is decomposed into FeCl2 and partially sublimed. At 500°C, second stage FeCl2 GIC reflections are observed on X-ray diffractograms, and at 750°C, all iron and chlorine are desorbed out of the graphene layers in polycrystalline graphite, whereas monocrystalline graphite always contains some amount of iron and chlorine. Thermogravimetric evolution has been followed using a McBain balance. FeCl3 desorption mainly occurs between 350 and 550°C, and is more quantitative in the case of polycrystalline materials. The graphite granulometry significantly influences the desorption level, and the higher the heating rate, the greater the FeCl3 desorption.