Comparison of Realistic and Slit Models of Activated Carbon for Xe/Kr Separation

This study compares the adsorption and separation performance
of
Xe/Kr mixtures in realistic and slit pore models of activated carbon
using Grand Canonical Ensemble Monte Carlo (GCMC) simulations. The
hybrid Reverse Monte Carlo (HRMC) model and slit pore structures exhibit
distinct adsorption behaviors influenced by pore size, pressure, and
temperature. For pure Xe and Kr, adsorption heats in the HRMC model
range from 12 to 20 kJ/mol for Kr and 15 to 25 kJ/mol for Xe. At 1
MPa, cs1000a achieves the highest adsorption capacities for Kr and
Xe, 1.93 and 3.84 mmol/g, respectively. In slit pores, the Xe/Kr selectivity
peaks at 32 for 0.8 nm pores at 0.1 MPa and decreases with pressure
and pore size. The 1.1 nm slit pore at 1.0 MPa and 238 K achieves
a maximum Xe adsorption capacity and selectivity of 14. Local density
analyses confirm selective Xe adsorption in narrow pores, with enhanced
multilayer adsorption in larger pores. Compared to the HRMC model,
slit pores exhibit higher adsorption heat and steeper isotherms, indicating
stronger interactions. This study highlights the importance of pore
structure in designing activated carbons for Xe/Kr separation, recommending
operating conditions of 1.1 nm pore width, 238 K, and 1.0 MPa for
optimal separation performance.