CO2 sorption on surface-modified carbonaceous support: Probing the influence of the carbon black microporosity and surface polarity

The use of solid sorbents is a convenient option in post-combustion CO2capture strategies. Sorbentsselection is a key point because the materials are required to be both low-cost and versatile in typi-cal post-combustion conditions in order to guarantee an economically advantageous overall process.This work compares strategies to tailor the chemico-physical features of carbon black (CB) by surface-modification and/or coating with a CO2-sorbent phase. The influence of the CB microporosity, enhancedby chemical/thermal treatments, is also taken into account. Three CB surface modifications are performedand compared: (i) oxidation and functionalization with amino-groups, (ii) coating with iron oxides and(iii) impregnation with an ionic liquid (IL). The CO2capture performance is evaluated on the basis of thebreakthrough curves measured at atmospheric pressure and room temperature in a lab-scale fixed bedmicro-reactor. Most of tested solids adsorb a CO2amount significantly higher than a 13X zeolite andDARCO FGD (Norit) activated carbon (up to 4 times more in the best case). The sorbents bearing basicfunctionalities (amino-groups and IL) exhibit the highest CO2sorption capacity. The use of a microporouscarbonaceous support limits the accessibility of CO2toward the adsorbing phase (IL or FM) lowering thenumber of accessible binding sites for CO2.