Effect of activating agents on the development of microporosity in polymeric-based carbon for CO2 adsorption

A single commercial carbon sorbent was treated with different activating agents such as carbon dioxide, water steam, ammonia, potassium hydroxide, and zinc (II) chloride, to compare their activating power toward evolution of microporosity beneficial for CO2 adsorption at ambient conditions. The activating agents improved the structural properties of the carbon studied and CO2 adsorption in the following order: ZnCl2 < H2O < NH3 < CO2 < KOH. Low-temperature nitrogen adsorption characterization showed that the CO2 adsorption depends mainly on the volume of micropores <1 nm. The KOH-activated carbon had the largest volume of these pores, which resulted in the highest CO2 uptake (6.9 mmol g−1 at 0 °C and 1 bar). Among activating agents studied KOH is the best activator for the structure development and improvement of CO2 adsorption.