Hierarchical nanostructured carbons as CO2 adsorbents

Abstract

Synthesis and characterization of hierarchical carbon materials, CMK-5 type, with high specific surface areas and large pore volumes is reported and tested in CO2 adsorption. These materials were successfully synthesized by the nanocasting process using a hard silica template SBA-15, furfuryl alcohol (FA) as carbon precursor, and 1,3,5-trimethylbenzene (TMB) as solvent. The percentage of FA, and the FA:TMB volume ratio were the synthesis parameters evaluated to determine the accurate amounts to impregnate the pore walls of the template. Both parameters influence the formation of carbon materials with a 2D porous structure and hexagonal tube array. CMK-5 materials achieved specific surface areas up to 2200 m2/g and total pore volumes ca. 2 cm3/g. The characterization techniques allowed us to establish a correlation between the different textural, structural and morphological properties and the carbon dioxide adsorption capacity. The CO2 adsorption capacity at 308 K up to 1 bar has a strong relationship only with the micropore volume, but at higher pressure (up to 10 bar) the CO2 adsorption capacity depends not simply on the amount of micropores but also of the small mesopores present in these carbons, reaching a maximum value of 7 mmol/g, at 308 K and up to 10 bar.