Thermogravimetric studies on the activation of nanometric carbon fibers

Summary

Nanometric vapor grown carbon fibers (VGCF) constitute an attractive, novel precursor for nanostructured fibrous carbon adsorbents, but their highly ordered structure is a possible drawback to activation. The objective of this work was to evaluate VGCF reactivity toward different agents for physical or chemical activation. TG results showed that CO<Subscript>2</Subscript> gasification of VGCF begins at about 823 K and becomes more pronounced above 1123 K. Catalyzed gasification was studied using VGCF impregnated with either 1 or 20 mass&percnt; K<Subscript>2</Subscript>CO<Subscript>3</Subscript> or KOH, which was gasified with CO<Subscript>2</Subscript> in the same thermobalance. Both compounds, especially KOH, exhibited strong catalytic effects on VGCF gasification. The VGCF were also impregnated with K<Subscript>2</Subscript>CO<Subscript>3</Subscript> and KOH in amounts typical for chemical activation. In this case, reaction begun at about 943 K, and reactivity was maximal at 1123 K. VGCF reactivity with KOH was higher than with K<Subscript>2</Subscript>CO<Subscript>3</Subscript>, the effects of both compounds becoming stronger as their concentrations increased.