Here, we report the preparation of microporous-activated carbons from a Brazilian natural lignocellulosic agricultural waste, cupuassu shell, by pyrolysis at 500 ºC and KOH activation under different experimental conditions and their subsequent application as adsorbent for CO2 capture. The effect of the KOH:precursor ratio (wt/wt%) and the activation temperature on the porous texture of activated carbons have been studied. The values of specific surface area ranged from 1132 to 2486 m2/ g, and the overall micropore volume ranged from 0.73 to 1.02 cm3/ g. Carbons activated with 2:1 ratio of KOH and activation temperature of 700 ºC presented a CO2 adsorption at 1 bar of 7.8 and 4.4 mmol/g at 0 °C and 25 ºC, respectively. The isosteric heat of adsorption, Qst , was calculated for all samples by applying the Clausius–Clapeyron approach to CO2 adsorption isotherms at both temperatures. The values of CO2 adsorption capacities are among the highest reported in the literature, especially for activated carbons produced from biomass.

Enhanced CO2 capture by cupuassu shell-derived activated carbon with high microporous volume
    Abstract
    1 Introduction
    2 Experimental
    3 Results and discussion
    4 Conclusions
    Acknowledgements 
    References

• Orlando F. Cruz Jr.(National Institute of Amazonian Research (INPA), Manaus, AM 69011‑970, Brazil, Graduate Program on Materials Science and Engineering (PGMAT), Federal University of Santa Catarina, Florianópolis, SC 88040‑900, Brazil)
• Ignacio Campello‑Gómez(Departamento de Química Inorgánica, Universidad de Alicante, 03080 Alicante, Spain)
• Mirian E. Casco(Department of Engineering, Universidad Católica del Uruguay, Av. 8 de Octubre 2738, 11600 Montevideo, Uruguay)
• Jarosław Serafin(Department of Inorganic and Organic Chemistry, University of Barcelona, Martí I Franquès, 1‑11, 08028 Barcelona, Spain)
• Joaquín Silvestre‑Albero(Departamento de Química Inorgánica, Universidad de Alicante, 03080 Alicante, Spain)
• Manuel Martínez‑Escandell(Departamento de Química Inorgánica, Universidad de Alicante, 03080 Alicante, Spain)
• Dachamir Hotza(Graduate Program on Materials Science and Engineering (PGMAT), Federal University of Santa Catarina, Florianópolis, SC 88040‑900, Brazil, Department of Chemical and Food Engineering, Federal University of Santa Catarina, Florianópolis, SC 88040‑900, Brazil)
• Carlos R. Rambo(Graduate Program on Materials Science and Engineering (PGMAT), Federal University of Santa Catarina, Florianópolis, SC 88040‑900, Brazil, Department of Electrical and Electronic Engineering, Federal University of Santa Catarina, Florianópolis, SC 88040‑900, Brazil)