Highly selective high-silica SSZ-13 zeolite membranes for H₂ production from syngas

A highly CO₂-selective high-silica SSZ-13 zeolite membrane was used for H₂ production by separating CO₂ from syngas (CO₂/H₂ mixture). High-silica SSZ-13 zeolite membranes were fabricated using outside asymmetric alumina tubes by secondary growth of ball-milled SSZ-13 seeds. The composition of membrane gel and synthesis time were modified. The Si/Al ratio in framework of the membrane was as high as 42 when SiO₂/Al₂O₃ ratio of the gel increased to 140. The effects of test parameters such as pressure drop, temperature, feed flow rate and concentration on membrane performance were investigated. The test pressure drop was up to 2 MPa. The ultra-high CO₂/H₂ selectivity of 161 with excellent CO₂ permeances of ~6.3 × 10⁻⁷ mol/(m² s Pa) (=3760 GPU) were observed for the best membrane at 243 K and pressure drop of 0.2 MPa. Carbon dioxide permeance through high-silica SSZ-13 zeolite membrane was 4.2 × 10⁻⁷ mol/(m² s Pa) (=2500 GPU) at 298 K and pressure drop of 2.0 MPa, and the CO₂/H₂ selectivity was 17.4. The current high-silica SSZ-13 zeolite membranes exceeded the upper bound of polymeric membranes and other inorganic membranes in CO₂/H₂ plots and owned great potentials for H₂ production from syngas.