High performance SSZ-13 membranes prepared at low temperature

Conventional hydrothermal synthesis usually generates thick zeolite membranes in the range of 2–10 μm, which lead to high diffusion resistance and low permeance. The synthesis of ultrathin zeolite membranes (thickness<1 μm) is extremely desirable but a great challenge. Ultrathin SSZ-13 membranes with thickness 0.4–0.7 μm were prepared by conventional hydrothermal synthesis at low temperature. The reduction of membrane thickness to sub-micron range mainly came from the slow crystallization kinetics at low synthesis temperature, which led to the formation of small SSZ-13 crystals and avoided the excessive membrane growth. The use of ball-milled nano CHA seeds for seeding also facilitated the formation of thin membranes. Low temperature synthesis avoided the use of expensive high-pressure autoclave and reduced energy consumption for membrane synthesis. Outstanding CO2 permeance of 4.8 × 10−6 mol/(m2ˑsˑPa) and CO2–CH4 selectivity of 153 were obtained at 0.14 MPa and room temperature. To the best of our knowledge, this is by far the thinnest SSZ-13 membrane with outstanding CO2–CH4 separation performance.