Separation of a Five-Component Gas Mixture by Pressure Swing Adsorption

Bulk separation of a five-component mixture simulating coal gasification products was performed by pressure swing adsorption (PSA) using activated carbon. The PSA cycle consisted of four commercially used steps: (I) pressurization with H2, (II) adsorption, (III) blowdown, and (IV) evacuation. Using this cycle, four products were obtained with a single PSA unit: H2 (over 99.7% purity), CO, CH4, and acid gas (CO2 + H2S). The first three products contained less than 0.001% H2S, and the acid gas was suitable for sulfur recovery. A mathematical model incorporating equilibrium adsorption of mixture and mass transfer resistance (of CO2) was found capable of simulating all steps of the PSA cycle. The model simulation results were in fair agreement with the experimental data. A fundamental understanding of the dynamics of the cyclic process was gained through the model.