CO2 Capture from Flue Gas on a Pilot Scale Using Porous Carbon Prepared from Cotton Stalk Crop Residues through an Industrially Viable Activation Process

With the aim to capture CO2 from flue gas, porous carbon was derived from abundantly available, nonfodder crop residue─cotton stalk via thermochemical methodology. The precursor was treated with a new combination of chemical activating agents (NaOH and K2SO4) in stoichiometric proportions and converted to porous carbon via a single-step activation. The transition to using this combination in place of the conventional KOH activation in the production of porous carbon offers an attractive industrial opportunity, due to the substantial drop in the cost of manufacturing. Extensive characterizations were performed on the derived carbon, which included XRD, XPS, Raman spectra, SEM, and TEM. Nitrogen adsorption–desorption isotherm analysis at 77 K revealed BET-specific surface areas of 1797 m2/g, along with CO2 uptake capacities of 4.77, 2.49, and 1.71 mmol/g at 273, 298, and 313 K, respectively. Furthermore, the breakthrough curve of CO2 adsorption in a fixed-bed column was studied at different flow rates and temperatures using the flue gas (11 ± 0.2% CO2 and 89 ± 0.2% N2) to analyze the equilibrium CO2 capacity of the porous adsorbent in dynamic conditions. As proof of the concept, the porous carbon was packed in a column cartridge and the adsorption of CO2 from flue gas emanating from a pilot-scale diesel-fired boiler was studied. This demonstrated that carbon cartridges can efficiently and practically remove CO2 from flue gas, especially in small-scale industrial applications.