CO2 Capture with Activated Carbon Grafted by Nitrogenous Functional Groups

Amino/nitro groups were introduced onto the surface of the activated carbon (AC) with nitration followed by reduction in order to improve its adsorption capacity toward CO2. These AC samples were characterized by N-2 adsorption/desorption, FTIR, and X-ray photoelectron spectroscopy (XPS). CO2 adsorption properties of the samples were investigated using a self-regulating high-pressure adsorption apparatus. Results showed that the contents of nitrogen on the treated samples' surface increased from 0% to 1.38 after modification. The maximum CO2 adsorption capacity of the modified samples can reach 19.07 mmol/g at 298 K and 36.0 bar. The adsorbed amounts of CO2 on all samples decreased with an increase in the adsorption temperature, but the extent of the decrease with the modified samples was less than that of the raw AC sample. CO2 adsorption capacities of the modified sample for five cyclic adsorption-desorption runs were found to be nearly identical.