Valorisation of spent coffee grounds as CO2 adsorbents for postcombustion capture applications

In this work spent coffee grounds from single-use capsules were used as the starting material for producing low-cost activated carbons. The activation conditions were selected and optimised to produce microporous carbons with high CO2 adsorption capacity and selectivity, thus with potential to be used as adsorbents in postcombustion CO2 capture applications. Two activation methods are compared: physical activation with CO2 and chemical activation with KOH. The first method is considered less contaminant; however, leads to carbons with lower textural development and thus lower CO2 adsorption capacity than those obtained by activation with KOH. On the other hand, multicomponent adsorption cyclic experiments pointed out that the CO2/N2 selectivity of physically activated carbons is higher than that of chemically activated carbons.