Adsorption and desorption characteristics of CF4 on fixed bed column

High throughput screening of pure silica zeolites for CF4 capture from electronics industry gas

The capture and separation of CF4 from CF4/N2 mixture gas is a crucial issue in the electronics industry, as CF4 is a commonly used etching gas and the ratio of CF4 to N2 directly affects process efficiency. Utilizing high-throughput computational screening techniques and grand canonical Monte Carlo (GCMC) simulations, we comprehensively screened and assessed 247 types of pure silicon zeolite materials to determine their adsorption and separation performance for CF4/N2 mixtures. Based on screening, the relationships between the structural parameters and adsorption and separation properties were meticulously investigated. Four indicators including adsorption selectivity, working capacity, adsorbent performance score (APS), and regenerability (R%) were used to evaluate the performance of adsorbents. Based on the evaluation, we selected the top three best-performing zeolite structures for vacuum swing adsorption (LEV, AWW and ESV) and pressure swing adsorption (AVL, ZON, and ERI) processes respectively. Also, we studied the preferable adsorption sites of CF4 and N2 in the selected zeolite structures through centroid density distributions at the molecule level. We expect the study may provide some valuable guidance for subsequent experimental investigations on adsorption and separation of CF4/N2.

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

The capture and separation of CF₄, C₂F₆, and SF₆ 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 CF₄, C₂F₆, and SF₆ 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.