Atomistic simulation study of the adsorptive separation of hydrogen sulphide/alkane mixtures on all-silica zeolites

The selective separation of the aggressive hydrogen sulphide gas from industrial streams is highly important from environmental and economic aspects. Capture of this substance from industrial gases of light hydrocarbons by all-silica zeolites can be an eco-friendly alternative to the other common absorption/adsorption procedures. The adsorption from binary mixtures of hydrogen sulphide and light alkanes (H2S/CH4, H2S/C2H6, and H2S/C3H8) on preselected all-silica zeolites was studied by atomistic simulations, using a recently developed force field for hydrogen sulphide. In addition to four experimental all-silica zeolite frameworks (DDR, CHA, ACO, CAS), three of their hypothetical relatives were also drawn into the investigations. The smaller pore size zeolites (ACO, CAS, and particularly one of the hypothetical zeolites) showed remarkable separation performances under real ambient conditions. Among the examined structural details of the studied frameworks, the calculated realistic pore size distributions proved the most appropriate in attempts to unravel the connection between adsorption selectivities and framework structural properties. The investigations were completed by a necessary demonstration of the translational accessibility of the inner cages of the smaller pore size zeolites.

Automated summary

Selective separation of aggressive hydrogen sulphide gas from industrial streams using all-silica zeolites is important environmentally and economically. Smaller pore size zeolites showed remarkable separation performances under real ambient conditions, and there is a connection between adsorption selectivities and framework structural properties.