Screening of zeolites for H2S adsorption in mixed gases: GCMC and DFT simulations

Zeolites with high Si/Al ratio are widely used in industrial desulfurization process because of their stability and hydrophobicity as adsorbents. However, the method to design a practical zeolites and the kinetics of competitive adsorption in multicomponent systems still remain to be studied. The adsorption capacity of H 2 S in 36 all-silica zeolites with different accessible area and pore size was calculated by the Grand Canonical Monte Carlo (GCMC) method. Identical method was used to simulate the adsorption behavior of H 2 S in the 5 widely used all-silica zeolites (CHA, BEA, MFI, LTA, FAU). Further, the adsorption properties of H 2 S in metal-modified SSZ was investigated using the Density Functional Theory (DFT) method. The simulation results display that the zeolites with a pore size of 7–9 Å and a higher accessible area tend to exhibit efficient adsorption at 313 K and atmospheric pressure. For pure H 2 S component, CHA adsorbs most H 2 S molecules at atmospheric pressure while FAU are more attractive for removal of H 2 S at saturation pressure. FAU shows a strong preferential adsorption on H 2 S in the presence of CO, CO 2 , H 2 O and N 2 . In addition, the Co-SSZ obtained by doping Co on CHA is the most promising adsorbent in this research. • Zeolites with high accessible area adsorb more H 2 S within a certain pore size range. • The key factors that affect the H 2 S adsorption are different under varying pressure. • CHA exhibits a good adsorption capacity but poor selectivity for H 2 S. • Co-modified SSZ shows excellent H 2 S adsorption performance in mixed components.