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

Abstract

With the aim to capture CO 2 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 K 2 SO 4 ) 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 m 2 /g, along with CO 2 uptake capacities of 4.77, 2.49, and 1.71 mmol/g at 273, 298, and 313 K, respectively. Furthermore, the breakthrough curve of CO 2 adsorption in a fixed-bed column was studied at different flow rates and temperatures using the flue gas (11 ± 0.2% CO 2 and 89 ± 0.2% N 2 ) to analyze the equilibrium CO 2 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 CO 2 from flue gas emanating from a pilot-scale diesel-fired boiler was studied. This demonstrated that carbon cartridges can efficiently and practically remove CO 2 from flue gas, especially in small-scale industrial applications.