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

Abstract

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.