Influence of the chemical activation with KOH/KNO3 on the CO2 adsorption capacity of activated carbons from pyrolysis of cellulose

Plant biomass is an attractive precursor to prepare activated carbons with high surface area for CO2 adsorption due to its low-cost and easy regeneration. Despite this interest, there are still remaining questions regarding the optimal processing conditions and the choice of activating agent. Moreover, since plant biomass shows a highly variable proportion of different biopolymers (cellulose, hemicellulose, lignin), it is important to understand the activation effect on each constituent. In this work, carbons obtained from pyrolysis of cellulose were activated using two potassium salts, using two different activation temperatures. The samples were characterized to elucidate the influence of the activation conditions on their CO2 adsorption capacity. In general, all the carbons activated at higher temperature showed higher adsorption capacity. These results are comparable with other carbons derived from biomass described in the bibliography. Among the activated carbons studied, the carbon activated only with KOH exhibits the highest CO2 adsorption capacity at 1 bar meanwhile the highest adsorption capacity at saturation pressure belongs to the carbon activated with larger ratio of KNO3. •Activated carbon was prepared from cellulose using KNO3:KOH in different ratios.•The interaction between KOH and KNO3 produces in a synergistic activation effect.•KNO3 activation results in carbons with enhanced CO2 adsorption due to increased number of active sites.•Tailoring the KOH/KNO3 ratio offers control of the pore size distribution of the carbon.