Exploring the potential of biomass-derived carbons for the separation of fluorinated gases with high global warming potential

Abstract

The development of advanced and innovative biomaterials with porous structural characteristics for the capture of fluorinated gases (F-gases) is important to contribute to the reduction of emissions of these gases with very high global warming potential. In this work, four biocarbons (CC-1:3H3PO4, CC-1:1H3PO4, CC-K2CO3 and CC-CO2) were produced by chemical and physical activation of corn cob biomass (CC). The adsorption equilibria of difluoromethane (R-32), pentafluoroethane (R-125), 1,1,1-tetrafluoroethane (R-125), 1,1,2-tetrafluoroethane (R-134a), sulphur hexafluoride (SF6), and nitrogen (N2) on these biocarbons were determined at 303.15 K. The highest adsorption capacities were obtained for CC-K2CO3 and CC-CO2 and a full characterization was also performed for these biomaterials at 283.15 and 323.15 K. On the other hand, the selectivities of SF6/N2 and the commercial refrigerants R-410A, R-407C, and R-407F were estimated using the Ideal Adsorption Solution theory (IAST). The results obtained for SF6/N2 show that the biocarbon CC-K2CO3 stands out from the other materials. In addition, the CC-CO2 shows a preference for R-32 over R-125 for the separation of the R-410A. Finally, CC-K2CO3 has a greater preference for R-134a over R-32 and R-125 in the R-407C and R-407F blends. Overall, these novel biocarbons improve the separation and purification of the F-gases under study, facilitating their application on a pilot scale.