Efficient synthesis of thin SSZ-13 membranes by gel-less method

Despite the high application potential in many important separation processes, high membrane cost is a leading obstacle for the commercial application of zeolite membranes. Compared with conventional hydrothermal synthesis, gel-less method has advantages like high material efficiency and easy control of membrane thickness. However, the development of gel-less method was limited to Silicalite-1 and A membranes due to the poor understanding of membrane formation mechanism and controlling parameters. Herein, we systematically investigated the effect of various parameters on the gel-less synthesis of SSZ-13 membranes for the first time. The obtained membranes were characterized by XRD, SEM, and CO2–CH4 separation. The key to the successful gel-less synthesis is to create an environment similar to that of conventional hydrothermal synthesis, which requires a delicate equilibrium between the template solution in the seed layer and the template solution at the bottom of autoclave. The thickness of SSZ-13 membrane can be controlled between 0.7−1.7 μm by manipulating the seed concentration in the dip-coating suspension. The obtained SSZ-13 membranes demonstrated high CO2 permeance 1.4–3.4 × 10−6mol/(m2⋅s⋅Pa) with decent CO2–CH4 selectivity of 35–116 at room temperature and 0.14 MPa.