Static state synthesis of STT zeolite membranes for high-pressure H2/CH4 separation

Abstract

STT zeolite membrane with seven-membered rings (7 MR) and nine-membered rings (9 MR) is an ideal alternative for the separation of hydrogen (H2) and methane (CH4). However, the successful synthesis is only possible in rotation conditions, which is difficult to achieve at an industrial scale. Herein we developed a static synthesis approach to prepare high-quality STT zeolite membranes. The precursor transformed in-situ from a liquid state to a semi-solid state to efficiently suppress the nucleation in the bulk gel. This did not affect the growth of the seed layer to form a continuous membrane. The water content was modulated between y = 44 and y = 124 in the molar composition of 1 SiO2: 0.2 TMAdaOH: y H2O. The precursor could be re-used one more time to reduce the total amount of chemical waste. The optimal H2 permeance and H2/CH4 mixture selectivity was up to 6.1 × 10−8 mol m−2 s−1 Pa−1 and 115 at atm pressure. The H2 permeation flux monotonically increased to 2.0 Nm3 m−2 h−1 under feed pressure up to 2.1 MPa. This paves the way for zeolite membranes to high-pressure H2 separation in practical applications.