Synthesis of porous carbon monolith adsorbents for carbon dioxide capture: Breakthrough adsorption study

Abstract

Abstract Carbon monoliths with bimodal porosity were obtained through nanocasting technique from silica monoliths (hard template) and furfuryl alcohol (precursor). These carbon adsorbents were evaluated as sorbents for CO2 capture by using a fixed-bed adsorption set up under dynamic conditions. Carbonization at different temperatures (550 to 950 °C) was carried out that resulted in the generation of different carbon adsorbents containing oxygen functional groups. The textural characterization results reveal the effect of nanocasting technique, which is confirmed from the generation of mesopores (0.41), micropores (0.85 cm3 g−1) and high surface area (1225.1 m2 g−1) of adsorbent synthesized at 950 °C, as shows highest CO2 uptake of 1.0 mmol g−1 at 30 °C and 12.5% CO2 concentration. The increase in the adsorption capacity with increasing CO2 concentration and decrease with the increasing adsorption temperature confirms the physisorption process. Five adsorption–desorption cycles show established materials with excellent regeneration stability as an adsorbent. Furthermore, three kinetic models along with three isotherms were used in the present study to analyze the adsorption data and found that fractional order kinetic model and Temkin isotherm fitted best. Thermodynamic studies suggested the exothermic, spontaneous as well as the feasibile nature of the adsorption process.