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With the aim to capture CO2from 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 CO2uptake capacities of 4.77, 2.49, and 1.71 mmol/g at 273, 298, and 313 K, respectively. Furthermore, the breakthrough curve of CO2adsorption in a fixed-bed column was studied at different flow rates and temperatures using the flue gas (11 ± 0.2% CO2and 89 ± 0.2% N2) to analyze the equilibrium CO2capacity 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 CO2from flue gas emanating from a pilot-scale diesel-fired boiler was studied. This demonstrated that carbon cartridges can efficiently and practically remove CO2from flue gas, especially in small-scale industrial applications.

Hydrogen-rich syngas was generated from Jatropha curcas(J. curcas) shell biomass char in a Fresnel lens solar concentrator assembly using solar thermal energy. The assembly had two lenses arranged in such a manner that the focal point of both coincided at a glass reactor, having a specially designed water inlet mechanism. A dual axis automatic solar tracking system working in a closed loop was utilized for continuously maintaining the focal point on the reactor so that the desired high temperature could be obtained for the reaction. The maximum temperature of 1087 °C with a geometrical concentration of 215× was reached at the focal plane. The theoretical efficiency of the system was found to be 67.44%. The simulated results of the predicted temperature were first verified experimentally without any reaction mixture, and they differed with an average error of 7.85%. J. curcasshell char was then steam gasified at the focus. A maximum char bed temperature of 736 °C could be achieved during the reaction, and 42.77% hydrogen gas was obtained in the combustible gas mixture. In this work, a cost-effective and modular assembly for high-temperature solar steam gasification is designed and fabricated to make the process attractive and environmentally benign.