Enhanced capacity to CO2 sorption in humid conditions with a K-doped biocarbon

Abstract

Abstract Solid sorbents with enhanced capacity and selectivity towards CO2 are crucial in the design of an efficient capture process. Among the possible alternatives, K2CO3-doped activated carbons have shown high CO2 capture capacity and rapid carbonation reaction rate. In this work, a sustainable and low-cost approach is developed with a biomass-based activated carbon or biocarbon as support. The CO2 capture performance in cyclic sorption–desorption operation and the sorption kinetics have been investigated under different scenarios in a purpose-built fixed-bed set-up. Independent of the H2O concentration in the flue gas, a constant relative humidity (∼20%) in the K2CO3-doped biocarbon bed promoted the carbonation reaction and boosted the CO2 sorption capacity (1.92 mmol/g at 50 °C and 14 kPa partial pressure of CO2). Carbonation is slower than physical adsorption of CO2 but wise process design could tune the operation conditions and balance capture capacity and sorption kinetics.