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

Abstract

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.