CHF₃–CHClF₂ Binary Competitive Adsorption Equilibria in Graphitic Slit Pores: Monte Carlo Simulations and Breakthrough Curve Experiments

Abstract

The separation and recovery of the greenhouse gases CHF3 and CHClF2 from emissions is essential to avoid adverse environmental effects. Nanoporous carbons are excellent candidates for the capture of CHF3. However, little research has been done on the effect of pore size on the adsorption capacity and selectivity of CHClF2 over CHF3 in nanoporous carbon materials. The effect of the pore size on the competitive adsorption of a binary CHF3–CHClF2 mixture in graphitic slit pores has been investigated using a combination of Monte Carlo simulations and breakthrough curve experiments over a wide range of pressures and temperatures. The entropy changes have a considerable effect on selectivity of CHClF2 over CHF3 because the size of the adsorbate molecule is close to the effective height of the pores; conversely, adsorption energy has a significant impact. The selectivity of CHClF2 over CHF3 at 0.05–1.0 MPa increases in the order 19.47 < 16.62 < 13.20 < 11.77 < 8.30 < 5.17 < 5.67 Å. The mechanisms for adsorption and the selectivity of CHClF2 over CHF3 were determined, as were the effects of pore size and pressure on adsorption energy and adsorption entropy. This combination of methods provides an effective strategy for the design and screening of adsorbent materials for CHF3–CHClF2 separation and recovery applications.

Molecular simulation of the effects of activated carbon structure on the adsorption performance for volatile organic compounds in fumes from gasoline

“…A three‐layer graphite sheet activated carbon model and the molecular structure of the adsorbent were built in Materials Studio software. The slit‐pore model simplifies activated carbon pores to the same slit shape and is widely used in gas adsorption simulations 25,26 . The graphene sheet size is 19.94 nm × 39.64 nm, and the vertical distance d between graphene sheets is the van der Waals radius of carbon atoms, which is taken as 0.34 nm in the model 27 .…”

“…The slit-pore model simplifies activated carbon pores to the same slit shape and is widely used in gas adsorption simulations. 25,26 The graphene sheet size is 19.94 nm  39.64 nm, and the vertical distance d between graphene sheets is the van der Waals radius of carbon atoms, which is taken as 0.34 nm in the model. 27 The activated carbon pore size D is defined as the distance between the centers of two carbon atoms in the upper and lower innermost graphite sheets.…”

Utilization of Two-Stage Vacuum Pressure Swing Adsorption Units for CHF3/CHClF2 Separation and Recovery

“…According to the adsorption data for CHF 3 and CHClF 2 on PK1, the coefficients of the adsorption isotherm equation are obtained; the relevant coefficients are listed in Table . The correlation coefficient of fitting for CHF 3 and CHClF 2 on PK1 is 99.69%.…”

Adsorption Characteristics of Refrigerants for Thermochemical Energy Storage in Metal–Organic Frameworks

“…The capture of refrigerants using porous materials, and in particular HFC, has been extensively investigated in the literature. Recently, Yancey et al, and Wanigarathna et al, reviewed the capture of HFC in porous materials, such as zeolites, − silica gel, , activated carbons, − and metal–organic frameworks (MOFs), − discussing their practical applications. Among the rest of the porous materials, MOFs are emerging as promising adsorbents for capturing and separating fluorocompounds.…”