Critical role of small micropores in high CO2 uptake

Abstract

Microporous carbon materials with extremely small pore size are prepared by employing polyaniline as a carbon precursor and KOH as an activating agent. CO(2) sorption performance of the materials is systematically investigated at the temperatures of 0, 25 and 75 °C. The prepared carbons show very high CO(2) uptake of up to 1.86 and 1.39 mmol g(-1) under 1 bar, 75 °C and 0.15 bar, 25 °C, respectively. These values are amongst the highest CO(2) capture amounts of the known carbon materials. The relation between CO(2) uptake and pore size at different temperatures is studied. An interesting and innovative point that the micropores with pore size smaller than a critical value play a crucial role in CO(2) adsorption at different temperatures is demonstrated. It is found that the higher the sorption temperature is, the smaller this critical value of pore size is. Pores smaller than 0.54 nm are manifested to determine CO(2) capture capacity at high sorption temperature, e.g. 75 °C. This research proposes a basic principle for designing highly efficient CO(2) carbon adsorbents; that is, the adsorbents should be primarily rich in extremely small micropores.

Biomass Waste Carbon Materials as adsorbents for CO2 Capture under Post-Combustion Conditions

“…Improved CO2 retention capacities have been ascribed to even smaller diameters as well (Martín et al, 2010;Wahby et al, 2010;Wei et al, 2012;Sethia and Sayari, 2015). Zhang et al (2013) described that critical pore size increased with decreasing adsorption temperature and found that micropores with sizes below 0.54, 0.7, and 0.8 nm were determinant for adsorption at 75, 25, and 0°C, respectively . However, inconsistencies between authors are common depending on the conditions or characteristics studied, and seeking an advanced adsorbent is still very much empirical (Martín et al, 2010).…”

High yield and high packing density porous carbon for unprecedented CO2 capture from the first attempt at activation of air-carbonized biomass

“…This is surprising because most previous studies have noted a widening of the adsorption knee at higher activation temperature. 29,56,57,[61][62][63][64][65][66][67][68][69][70][71][72][73][74] The level of porosity generated, as judged by the amount of nitrogen adsorbed, increases modestly for samples prepared at higher activation temperature despite the non-changing nature and shape of the isotherms. The isotherms of the compactivated carbons are similar to those of analogous conventionally activated carbons except that they exhibit higher amounts of nitrogen sorption.…”

Assessment of CO2 Adsorption Capacity on Activated Carbons by a Combination of Batch and Dynamic Tests

“…The hydrogen-based fuel cells 2,3 , an immediate and effective CO 2 mitigation can be pursued by the 41 adoption of appropriate post combustion technologies. The use of porous solids for CO 2 capture 4 towards ultramicropores 13,26,[29][30][31] .…”