Highly-efficient separation of SF 6 /N 2 and NF 3 /N 2 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 SF 6 /N 2 and NF 3 /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 SF 6 /N 2 and NF 3 /N 2 mixtures. By tuning the carbonization temperatures in the range of 600–850 °C, the optimal PC-750 with dense and abundant micropores at 0.5–0.8 nm is obtained. Resultantly, PC-750 exhibits a high SF 6 uptake of 4.09 mmol·g −1 and record SF 6 /N 2 selectivity of 436.4 among the reported carbon adsorbents at 298 K and 100 kPa. Significantly, the NF 3 /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 SF 6 and NF 3. Furthermore, the adsorption kinetics and dynamic breakthrough experiments verify the rapid adsorption rate, excellent separation performance of SF 6 /N 2 and NF 3 /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 SF 6 /N 2 and NF 3 /N 2.