Vol.:(0123456789) 1 3 Adsorption https://doi.org/10.1007/s10450-019-00089-3 Hierarchical nanostructured carbons as CO 2 adsorbents Kiara Montiel‑Centeno 1  · Deicy Barrera 1  · Jhonny Villarroel‑Rocha 1  · M. Sergio Moreno 2  · Karim Sapag 1 Received: 1 August 2018 / Revised: 2 April 2019 / Accepted: 16 April 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Synthesis and characterization of hierarchical carbon materials, CMK-5 type, with high specifc surface areas and large pore volumes is reported and tested in CO 2 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 infuence the formation of carbon materials with a 2D porous structure and hexagonal tube array. CMK-5 materials achieved specifc surface areas up to 2200 m 2 /g and total pore volumes ca. 2 cm 3 /g. The characterization techniques allowed us to establish a correlation between the diferent textural, structural and morphological properties and the carbon dioxide adsorption capacity. The CO 2 adsorption capac- ity 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 CO 2 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. Keywords CMK-5 · Hierarchical nanostructured carbons · CO 2 capture · Gas adsorption · Textural characterization 1 Introduction The economic and social growth of recent decades has led to an exponential increase in carbon dioxide (CO 2 ) emis- sions into the atmosphere and has also contributed signif- cantly to the global warming of the planet (Songolzadeh et al. 2014). Due to the difculty to reduce the CO 2 emis- sions, global eforts have been dedicated to the development of new technologies or processes to its capture or storage. Nowadays, most commercial processes use separation mem- brane or chemical absorption with alkaline liquid solutions based on amines, which are widely used, mainly for their high efciency in capturing CO 2 (Sevilla and Fuertes. 2012). However, amine-based processes have certain disadvantages such as the corrosion of the equipment where the process is performed, the volatilization or degradation of the liquid absorbent and a signifcant energy consumption associated with the regeneration of the material (Estevez et al. 2018). As a result of these limitations, many alternative solutions are sought for the capture and storage of this greenhouse gas. One of the possible alternatives is based on the adsorp- tion processes using porous solids such as metal–organic framework (MOF), zeolites, mesoporous silica and porous carbons (Lee and Park 2015). Among diferent adsorbent materials, microporous carbons such as activated carbons are one of the most used in CO 2 capture processes, since require simple synthesis processes, are chemically and hydrother- mally robust and have high specifc sur face areas. None- theless, some mesoporous carbons have shown higher CO 2 adsorption capacity than microporous activated carbon. The thermodynamic measurements indicate that CO 2 is captured by a physisorption mechanism which involves direct access (through mesopores) to the micropores within the material (Durá et al. 2016). On the other hand, activated carbons gen- erally have a disordered and undefned pore structure, and as a result, both gas adsorption and regeneration processes become more complex. This opens a new approach to design efcient adsorbents with micropores and mesopores in an ordered porous structure. One option that has attracted con- siderable attention are the hierarchical nanoporous carbons * Deicy Barrera deicybarrera@gmail.com 1 Laboratorio de Sólidos Porosos, Instituto de Física Aplicada, CONICET, Universidad Nacional de San Luis, Ejército de los Andes 950, CP 5700 San Luis, Argentina 2 Centro Atómico Bariloche, 8400 San Carlos de Bariloche, Argentina