Aleksandra Dziura

Benzene and Methane Adsorption on Ultrahigh Surface Area Carbons Prepared from Sulphonated Styrene Divinylbenzene Resin by KOH Activation

A commercially available styrene divinylbenzene ion-exchange resin, Amberjet 1200 H, was used to prepare a series of activated carbons through carbonization and subsequent activation with varying amounts of KOH. The resulting activated carbons showed a well-developed porous structure with specific surface area in the range of 730–3870 m2 g−1, total pore volume in the range of 0.44–2.07 cm3 g−1 and micropore volume in the range of 0.30–1.59 cm3 g−1. Importantly, these structural parameters can be changed by varying the amount of KOH used for the activation. These carbons showed extremely good adsorption properties towards benzene and methane at 20°C. The best uptakes for benzene and methane (19.6 and 1.68 mmol g−1, respectively) were obtained for the carbon activated using the KOH/C ratio of 4. These values correspond to the gravimetric adsorptions of 1.53 g/g and 27 mg/g, respectively. Benzene adsorption was analyzed using the Dubinin–Radushkevich (DR) equation. The micropore volume calculated using the DR equation based on benzene adsorption corresponds well with the micropore volume calculated from nitrogen adsorption by the αs comparative method. The high values of the structural parameters and the resulting high benzene and methane uptakes render the obtained activated carbons as prospective materials for use in environmental remediation and energy-related applications such as volatile organic compound adsorption and methane storage.

Adsorption Properties of Micro-/Meso-porous Carbons Obtained by Colloidal Templating and Post-synthesis KOH Activation

Nitrogen adsorption studies have been employed to examine the structural properties of micro-/meso-porous carbons obtained by colloidal templating and post-synthesis KOH activation. These carbons were prepared by polymerizing phenol and formaldehyde in the pores of a colloidal silica template followed by carbonization, silica dissolution and post-synthesis KOH activation. Colloidal silica was used to create spherical mesopores, while KOH activation was performed to create additional microporosity and to enlarge the surface area of the resulting carbons. Nitrogen adsorption studies showed that a single impregnation of the colloidal silica template with phenolic resin precursors afforded carbons with relatively thin pore walls which did not withstand the post-synthesis KOH activation; however, a double impregnation generated mesoporous carbons with thicker pore walls. Activation of these latter carbons with KOH created micropores in the mesopore walls without significant deterioration of the mesopore structure. The resulting mesoporous carbons possessed high specific surface areas (ca. 800 m2/g) and large single-point pore volumes (ca. 1.8 cm3/g). The post-synthesis KOH activation enlarged the surface area up to 1500 m2/g, which was achieved via the creation of microporosity. Hence, the carbon obtained by double impregnation and activation exhibited a single-point pore volume of ca. 2 cm3/g with a relatively high microporosity which attained 17% of the total porosity. High-surface-area micro-/meso-porous carbons are attractive for adsorption, catalysis and energy-related applications such as capacitors and batteries.