Preparation and testing of CO2-adsorbent carbons from carbon black

In the general framework of CO2 capture and sequestration, the synthesis and characterization of raw and/or functionalized materials as zeolites and carbon materials for CO2 capture are subject of a huge number of works. In this work cheap and renewable carbon based materials with well defined chemical-physical features were prepared and tested as CO2 sorbents. Hydrophilic carbon-based nanoparticles (HNP) were prepared starting from a commercial carbon black (CB) by using a wet oxidation route. Three different HNP, namely HNP4, HNP15 and HNP24, with an increasing oxygen loading (19,7, 21,0 and 32,0 wt.%, respectively) were produced. The oxidation treatment coupled with a moderate heating (< 450°C) in inert environment (He) was shown to increase the specific BET surface area from 150 m2/g (raw CB) to 460 m2/g (HNP24). A 15% CO2/N2 mixture, selected for the CO2 adsorption tests, is representative of the average CO2 level emitted from traditional and advanced combustion systems. Adsorption of CO2 into meso and micro-pores of HNP was evaluated by programmed thermal desorption (TPD) of the CO2 from the materials. The CO2 adsorption capacities of HNP were studied at 25°C at atmospheric pressure. The HNP samples were pretreated in He at 450°C before the adsorption tests. The physical and chemical properties of the raw CB and HNP have been carefully determined before and after the thermal pretreatment by thermogravimetry and ATR-FTIR spectroscopy. The regeneration of the HNP after repeated CO2 adsorption cycles was also studied.