The effect of precursor chemistry and preparation conditions on the formation of pore structure in metal-containing carbon fibers

Activated carbon fibers (ACFs) prepared from petroleum isotropic pitch and the same containing silver and cobalt nitrate, cobalt and palladium acetylacetonates, as well as mixtures of two salts with a total metal or metal mixture content of 1 wt% have been studied. The processing parameters are summarized for activated carbon fibers containing individual metals and metal mixtures. The results suggest that the generation of metal-containing particles and the formation of pore structure depend on many different factors including the composition of the metal and pitch precursors, the interaction of the metal and pitch precursors during the fiber production process, and the interaction between the two metal precursors when more than one metal salt is used. The addition of silver and cobalt in the form of nitrate salts enlarges the micropores and generates small mesopores with a narrow range of sizes. The addition of palladium as an acetylacetonate salt leads to the formation of both small micropores and larger mesopores. The cobalt additive as an acetylacetonate salt catalyzes the activation process, creating large mesopores and macropores. Mixing of two different metal precursors affects the particle composition and size. This, in turn, controls the pore structure of the final activated fibers. During activation, the two metal precursors can act independently (Ag/Co mixture). However, in other cases their effect can be additive (Co/Pd mixture), or even synergistic (Ag/Pd mixture).