Preparation of Porous Carbons from Petroleum Pitch and Polyaniline by Thermal Treatment for Methane Storage

The methane storage capacity of two series of activated carbons, obtained from a graphitizable (petroleum pitch) and a nongraphitizable precursor (polyaniline), has been evaluated after different thermal treatments. Both samples have been pyrolyzed and subsequently activated with KOH to obtain a highly developed microporous structure. After the synthesis, samples have been heat-treated at different temperatures, between 1000 and 1500 °C, to introduce structural changes that could have an effect on two parameters defining the methane adsorption capacity: the porosity and the density. The physicochemical characterization of the samples has shown that the activation process destroys the pregraphitic structure, with a development of microporosity. However, during the subsequent thermal treatment, the graphitic order can be partially recovered, especially with the graphitizable material, together with a decrease in the micropore volume and an enhancement of the density. The electrical conductivity of the activated carbon obtained from a graphitizable precursor improves much more with an increase in the temperature of the thermal treatment than that of the activated carbon obtained from a nongraphitizable precursor. It is worth highlighting that the high methane adsorption capacities achieved with some of these samples, reaching values as high as 180 V/V. These values are among the highest reported in the literature so far.