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.