Hydrogen sulfide permeation and hydrocarbon separation properties in cellulose triacetate hollow fiber membrane for high hydrogen sulfide contained natural gas sweetening applications

Hydrogen sulfide (H₂S) permeation and hydrocarbon (HC) separation was investigated on commercial asymmetric cellulose triacetate (CTA) hollow fiber membranes with H₂S included HC mixed-gas under realistic field conditions. The H₂S containing gas mixture used for this study was 5% CO₂, 21% H₂S, 15% C₂H₆, 10% C₃H₈ balanced with CH₄. The mixed-gas permeation tests were carried out with three temperatures, 15 °C, 25 °C, and 35 °C, and four pressures, 15 bar, 29 bar, 39 bar, and 46 bar. The permeate header pressure is 1.013 bar (atmospheric pressure). H₂S mixed-gas permeation was increased with increasing feed pressure. At the lower feed pressure between 15 bar and 30 bar, the H₂S/HCs selectivity were essentially stable. However, the selectivity is drastically decreased at the feed pressure of 30 bar and higher. The high condensability and solubility of H₂S at the pressure higher than 30 bar would increase a mobility of the CTA polymer chain segments dramatically.