Scalable fabrication of highly selective SSZ-13 membranes on 19-channel monolithic supports for efficient CO₂ capture

Zeolite CHA (SSZ-13) membranes with record-high CO₂/N₂ selectivities are reproducibly prepared on 19-channel monolithic supports by one-step secondary growth approach using the concentrated gel and vacuum seeding. Packing density and mechanical strength for the monolithic membranes are much higher than those for normal tubular and disc membranes. The membrane thickness in each channel of the monolithic support is quite uniform after synthesis modification. The best 19-channel monolith supported SSZ-13 membrane with an effective area of 85 cm² shows high CO₂/CH₄ selectivity of 132 with CO₂ permeance of 464 × 10⁻⁹ mol/(m² s Pa) at 298 K and pressure drop of 0.2 MPa for an equimolar CO₂/CH₄ mixture. The membrane also has the highest CO₂/N₂ selectivity of 46 among zeolite membranes to date. Large-area monolithic SSZ-13 membrane elements with an effective area of 270 cm² are fabricated in the same way. It is larger than the surface area of industrial tubular supports. The large-area membrane still displays high CO₂/CH₄ and CO₂/N₂ selectivities of 120 and 44 under the same test conditions, respectively, indicating that the current synthesis procedure is scalable. The effects of temperature and pressure drop on the separation performance of the monolithic membranes are investigated. The 19-channel monolithic SSZ-13 membrane with improved packing density is a good candidate for CO₂ capture from natural gas and flue gas.