Pith based spherical activated carbon for CO2 removal from flue gases

Serials of pitch based spherical activated carbons (PSACs) were prepared and used as adsorbent for CO2 adsorption from flue gases. The results indicate that the ultrafine micropores (<1 nm) are effective pores for CO2 adsorption, and the equilibrium adsorption capacity of CO2 has a linear relationship with the specific surface area of ultrafine micropores (S<1 nm). The adsorption capacity of CO2 can obtain 1.12 mmol/g at 15 kPa and 30 °C on one of PSAC sample due to its high S<1 nm (845 m2/g). Because the molecular CO2 can be polarized into polar molecules and has four kinds of adsorption configuration, the adsorption selectivities of CO2 vs. N2 and O2 are 86.99% and 69.91%, respectively. When the combined Electric Swing Adsorption and Vacuum Swing Adsorption were applied for CO2 desorption, about 100% desorption efficiency can be obtained, the desorption rate is twice of that with Temperature Swing Adsorption (TSA) and the energy consumption is only 69% of that with TSA.

► Spherical activated carbon as adsorbent for CO2 capture with a low pressure drop.
► The ultrafine micropores play a crucial role on the adsorption capacity of CO2.
► Molecular CO2 can be polarized and has four kinds of adsorption configurations.
► A high desorption efficiency was obtained using the combined ESA–VSA.