Micro/Mesoporous Activated Carbons Derived from Polyaniline: Promising Candidates for CO₂ Adsorption

A series of activated carbons were prepared by carbonization of polyaniline at different temperatures, using KOH or K₂CO₃ as activating agent. Pure microporous or micro/mesoporous activated carbons were obtained depending on the preparation conditions. Carbonization temperature has been proven to be a key parameter to define the textural properties of the carbon when using KOH. Low carbonization temperatures (400–650 °C) yield materials with a highly developed micro- and mesoporous structure, whereas high temperatures (800 °C) yield microporous carbons. Some of the materials prepared using KOH exhibit a BET surface area superior to 4000 m²/g, with total pore volume exceeding 2.5 cm³/g, which are among the largest found for activated carbons. On the other hand, microporous materials are obtained when using K₂CO₃, independently of carbonization temperature. Some of the materials were tested for CO₂ capture due to their high microporosity and N content. The adsorption capacity for CO₂ at atmospheric pressure and 0 °C achieves a value of ∼7.6 mmol CO₂/g, which is among the largest reported in the literature. This study provides guidelines for the design of activated carbons with a proper N/C ratio for CO₂ capture at atmospheric pressure