Highly-efficient Separation of SF6/N2 and NF3/N2 with Record Selectivity on One-Step Synthesized Carbon Nanosheet

The rich micropore development in porous adsorbents has been widely recognized as an indispensable prerequisite for effectively separating SF6/N-2 and NF3/N-2, while the fast adsorption kinetics is also essential to improve the overall adsorption-separation efficiency. In this work, the carbon nanosheet adsorbents with easily accessible micropores were synthesized via one-step self-activation method using potassium citrate as a precursor, and were systematically evaluated for the adsorptive separation of SF6/N-2 and NF3/N-2 mixtures. By tuning the carbonization temperatures in the range of 600-850 degrees C, the optimal PC-750 with dense and abundant micropores at 0.5-0.8 nm is obtained. Resultantly, PC-750 exhibits a high SF6 uptake of 4.09 mmol center dot g(-1) and record SF6/N-2 selectivity of 436.4 among the reported carbon adsorbents at 298 K and 100 kPa. Significantly, the NF3/N-2 selectivity reaches up to 61.4 for PC-750 under the same conditions, surpassing all the reported adsorbents. Additionally, the correlation between volume of different pores sizes and gas uptake well explains the adsorption performance of SF6 and NF3. Furthermore, the adsorption kinetics and dynamic breakthrough experiments verify the rapid adsorption rate, excellent separation performance of SF6/N-2 and NF3/N-2, as well as recyclability of PC-750 adsorbent. These findings are beneficial for the rational design of more highly-efficient carbon adsorbents for separating SF6/N-2 and NF3/N-2.