Ammonia permeation of fluorinated sulfonic acid polymer/ceramic composite membranes

NH3 is potentially an eco-friendly source of energy that normally is produced from H2 and N2 via the Haber-Bosch process under harsh conditions (400–500 °C and 10–30 MPa) with iron-based catalysts. The recent development of low-temperature active catalysts, however, could allow this reaction to proceed below 250 °C. Therefore, the development of a membrane system that could combine these low-temperature active catalysts with membranes selective for NH3 would be beneficial. In this study, the fluorinated sulfonic acid polymers Nafion and Aquivion were used to fabricate novel polymer/ceramic composite membranes. Following characterization by DLS, TG, and FT-IR measurements, Nafion and Aquivion solutions were coated onto ceramic porous supports and dried at 150 °C for use in fabricating fluorinated sulfonic acid polymer/ceramic composite membranes, and the permeances for NH3, H2, and N2 were evaluated. In comparisons with conventional polymer membranes, the fluorinated sulfonic acid polymer/ceramic composite membranes were thermally stable even at 200 °C. The Nafion and Aquivion-H+/ceramic membranes showed single-component NH3 permeance that reached >9.30 × 10−7 mol m−2s−1Pa−1 and >1.55 × 10−6 mol m−2s−1Pa−1 at 50–200 °C, respectively. Moreover, NH3 permeance of >2.31 × 10−6 mol m−2 s−1 Pa−1 was obtained from Aquivion-H+ with NH3 selectivity >90 for NH3/H2 and >800 for NH3/N2 at 50 °C in a mixed system.