CF₄ adsorption on porous carbon derived from silicon carbide

Considering the increasing industrial demand for CF₄ and its high global warming potential, appropriate disposal methods for CF₄ are required. Adsorption can not only be used for CF₄ capture but is also promising for increasing CF₄ concentration, which enhances the efficiency of conventional combustion methods. In this study, porous carbons were synthesized through the chlorination of silicon carbide (SiC) with two different polymorphs at high temperatures (ranging from 800 to 1200 °C) for application to CF₄ separation. The effects of the pore structure and surface morphology of the porous carbons on the CF₄ adsorption performance were analyzed. The porous carbon treated at a higher temperature had a well-developed pore structure, and the maximum total pore volume and specific surface area were obtained in the sample chlorinated at 1200 °C. However, the CF₄ adsorption uptake was well correlated with the narrow micropore volume for which the pore size was <0.9 nm rather than the total pore volume and specific surface area. Because of the different stacking in the precursors, alpha SiC formed a more amorphous structure in the porous carbon than beta SiC after chlorination, and the amorphous structure was thermodynamically favorable for CF₄ adsorption. Therefore, alpha-SiC-derived porous carbon chlorinated at 1100 °C had the highest CF₄ adsorption uptake of 2.32 mol kg⁻¹. It also exhibited excellent adsorption–desorption cyclic stability and reasonable CF₄/N₂ selectivity, indicating the applicability of the developed CF₄ adsorbent.