Activated carbons with high micropore volume obtained from polyurethane foams for enhanced CO2 adsorption

•Activated carbons (AC’s) were produced from PU-foams.•Activation with KOH yields highly microporous carbon.•CO2 uptakes as high as 5.0 mmol/g at 25 °C were obtained.•Immersion calorimetry indicates a high dependency of pore size on CO2 uptake. Microporous activated carbons with remarkably high CO2 uptake have been synthesized using polyurethane (PU) commercial foams as precursors. The PU samples were pyrolyzed at different temperatures in N2 atmosphere and chemically activated with KOH. Adsorption isotherms at 0 °C and 25 °C and immersion calorimetry were applied to provide a deeper knowledge about the most relevant factors implied in CO2 capture process explaining, hence, the values of adsorption obtained. CO2 adsorption uptakes reached values of 7.4 mmol/g at 0 °C, 5.0 mmol/g at 25 °C and 2.7 mmol/g at 50 °C. The remarkably high values of CO2 uptake are closely related with the BET specific surface area of the carbon foams but also with the high volume of narrow micropores all the samples present a high volume of micropores (between 0.59 and 0.71 cm3/g) as also confirmed by immersion calorimetry.