CF4 adsorption on porous carbon derived from silicon carbide

Abstract

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 degrees 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 degrees C. However, the CF(4 )adsorption uptake was well correlated with the narrow micmpore 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 degrees C had the highest CF4 adsorption uptake of 2.32 mol kgD(-1). It also exhibited excellent adsorption-desorption cyclic stability and reasonable CF4/N-2 selectivity, indicating the applicability of the developed CF4 adsorbent.