Removal of percentile level of H 2S from pressurized H 2S–CH 4 gas mixture using hollow fiber membrane contactors and absorption solvents

Abstract

In the present paper, the removal of percentile level of H 2S from pressurized binary gas mixture (2% H 2S in CH 4) up to 50 bar using hollow fiber membrane (HFM) contactors and absorption solvents is described. Unlike the related recent work on the removal of CO 2 from pressured gas streams [S.A.M. Marzouk, M.H. Al-Marzouqi, M.H. El-Naas, N. Abdullatif, Z.M. Ismail, Removal of carbon dioxide from pressurized CO 2–CH 4 gas mixture using hollow fiber membrane contactors, J. Membr. Sci. 351 (2010) 21–27], experiments with hazardous and highly toxic gas such as H 2S especially at high concentration (i.e., 20,000 ppm) and pressures necessitated essential modifications of the previously described experimental setup to ensure safe operations. In addition, an improved module design was proposed to simplify the recycling of the stainless steel module body while retaining the essential advantage of operating at high pressures. The modules were equipped with expanded polytetrafluoroethylene (ePTFE) hollow fibers. H 2S absorption rates were investigated using distilled water (as a physical solvent) and aqueous sodium hydroxide and amine solutions of different concentrations as chemical solvents. The experimental results indicated that H 2S flux was enhanced by increasing the inlet gas pressure for both physical and chemical absorption solvents. Similar to the trend reported previously for CO 2, the increase of H 2S flux in case of physical absorption was more pronounced than that obtained with chemical absorption. The ratio between H 2S and CO 2 fluxes into water agreed very well with the solubility ratio of these two gases, respectively, which is expected for physical solvents such as water. Up to the authors’ best knowledge, the present work is the first report on the experimental high pressure removal of percentile levels of H 2S from gas stream using HFM contactors and absorption solvents.