Separation of CF₄/N₂, C₂F₆/N₂, and SF₆/N₂ Mixtures in Amorphous Activated Carbons Using Molecular Simulations

Abstract

The capture and separation of CF 4 , C 2 F 6 , and SF 6 and their mixtures containing nitrogen is a challenging process. To solve this, we propose the use of saccharose coke-based carbons as membranes for the adsorption and separation of these gases. By means of advanced techniques of Monte Carlo and molecular dynamics simulations, we have studied the adsorption and diffusion of CF 4 , C 2 F 6 , and SF 6 as well as their mixtures with nitrogen in three HRMC carbon models, namely, CS400, CS1000, and CS1000a. We have computed the adsorption isotherms of the single components and the heat of adsorption as a function of the adsorbed concentration. We have also calculated the competitive adsorption of fluoride molecules and nitrogen at two different molar fractions, 0.1 and 0.9. We have computed the transport properties of the adsorbed gases in terms of the self-diffusivities and corrected diffusivities. The performance of the membranes for the targeted separations has been characterized by the calculation of the permselectivity. Our results indicate that the activated amorphous carbon CS1000a is an efficient adsorbent for the capture of the fluoride adsorbates as well as their purification from nitrogen-based mixtures.

Adsorption Interface-Induced H...F Charge Transfer in Ultramicroporous Metal–Organic Frameworks for Perfluorinated Gas Separation

“…Adsorptive separation based on nanoporous adsorbents is a promising method for recovering and purifying F-gases from waste streams because of its high energy efficiency and operational feasibility . A suitable adsorbent plays a vital role in the overall performance of the adsorptive separation process, − in particular, to capture F-gases from waste streams with a low F-gas concentration (from ppm to several percent). Porous adsorbents such as activated carbon and zeolites have been studied for the adsorptive separation of NF 3 /N 2 , CF 4 /N 2 , and SF 6 /N 2 mixtures. − However, the selectivity of F-gases/N 2 or activated carbon is undistinguished due to its chaotic pore structures.…”

CF4 Capture and Separation of CF4–SF6 and CF4–N2 Fluid Mixtures Using Selected Carbon Nanoporous Materials and Metal–Organic Frameworks: A Computational Study

“…To achieve an efficient CF 4 capture, several technologies based on thermal decomposition, plasma treatment, absorption, adsorption, cryogenic recovery, and membrane separation have been developed. Among them, physical adsorption using efficient nanoporous adsorbents ,,− is considered as the most competitive technology for capturing CF 4 due to its low energy consumption, low cost, and easy management. However, only some limited studies in the literature are devoted to CF 4 capture using nanoporous adsorbents.…”

Fluorine-functionalized Porous Organic Polymers for Durable F-gas Capture from Semiconductor Etching Exhaust

“…In addition, all the available destruction/abatement methods are highly expensive and are the least desirable for the environment (e.g., toxic fluoride wastes and NO x formed) . Recovery/recycle technologies for reducing F-gas emissions based on porous adsorbents are considered an economical and effective separation technology to remove the F-gases in the semiconductor exhaust, benefiting from its low energy consumption and high operational feasibility. − Many porous adsorbents such as activated carbon, silicon carbide, zeolite, alumina, and some metal–organic frameworks have been explored to adsorb these F-gases. − However, the residual toxic/corrosive components (e.g., HF and NO x ) from the process exhaust will disrupt the structure of these conventional adsorbents, tending to poor durability. − Another alternative emerging porous material, porous organic polymers (POPs), is more competitive in the adsorption and separation of toxic/corrosive F-gas components due to their high stability of the covalent bond link mode. − Furthermore, the permanent pores and interconnected pore structure of POPs can minimize the diffusion resistance of adsorbates, thereby improving their selectivity and recovery efficiency.…”