Communication Dans Un Congrès Année : 2024

Nitrogen enriched activated carbons for the CO2 capture and separation

Vincent Nicolas
Alain Celzard
Vanessa Fierro

Résumé

Decarbonisation of industry is necessary to limit the impact of carbon dioxide gas emissions on global climate warming. Numerous researches are presently focused on the separation of carbon dioxide from industrial gases, the purification of biogas and also on the underground storage of CO2. Adsorbent materials, in particular activated carbons, are promising for CO2 adsorption or separation.Activation of nitrogen-rich precursors with ammonia gas enabled to obtain various nitrogen-enriched activated carbons (nitrogen content up to 10 mass %). The starting materials are powdered chitosan (CS, 7 mass % N), freeze-dried chitosan hydrogel beads (BCS), coffee grounds (MC, 3 mass % N) and powdered polyacrylonitrile (PAN, 26 mass % N). Samples were prepared in two steps: (i) pyrolysis (10°C.min-1, 900°C, N2 200 mL.min-1) of pristine material and (ii) gasification at 900°C (NH3 flow 20-40 mg.min-1, contact time : 30-120 min) of the char obtained by pyrolysis.The physisorption isotherms of N2 at 77K and CO2 at 273K indicate that the prepared activated carbons are mainly microporous (0.11-0.62 cm3.g-1) with high ultramicroporous volumes (0.11-0.25 cm3.g-1). Under similar activation conditions, the BET specific surface areas and microporous volumes of the activated carbons follow the trend: BCS > CS > MC > PAN. The initial porosity of the lyophilised beads promotes the activation and allows to obtain both microporous and mesoporous carbons (type I(b) + IV N2 physisorption isotherm). The surface functionalities of some carbons were characterised by X-ray photoelectron spectroscopy (XPS) and elemental analysis.The adsorption capacity of the studied activated carbons at 1 bar and 273K tends to 5 mmol.g-1 as the BET specific surface area and the microporous volume increase. Higher CO2 adsorption capacities were obtained for carbons from lyophilised chitosan beads (SBET=1390 m2.g-1) and from chitosan powder (SBET=744 m2.g-1, 5.8 mass % N).The ideal CO2 selectivitities with respect to N2 and CH4 was calculated from the pure gases adsorption isotherms (0-35 bar, 0-75°C) for an activated carbon (CS, 60 min activation, SBET=998 m2.g-1). The values at 1 bar are 21 and 3.4 for CO2/N2 mixture (15 vol. % CO2, 50°C) and CO2/CH4 mixture (50 vol. % CO2, 25°C), respectively, whereas the desired target selectivity is > 50 for the former.

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Dates et versions

hal-04708769 , version 1 (21-11-2024)

Identifiants

  • HAL Id : hal-04708769 , version 1

Citer

Kouassi Fabrice N'Gole, Rafael Augusto MORALES OSPINO, Laurence Reinert, Bernard David, Vincent Nicolas, et al.. Nitrogen enriched activated carbons for the CO2 capture and separation. Interface Against Pollution 2024 (IAP2024), Sep 2024, Turin (IT), Italy. ⟨hal-04708769⟩
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