A super-permeable and highly-oriented SAPO-34 thin membrane prepared by a green gel-less method using high-aspect-ratio nanosheets for efficient CO₂ capture

High-efficient and green preparation of super permeable zeolite membranes is highly desired for scientific and application purposes. The normal gel-filled synthesis of zeolite membrane raises the problems including environment, safety and efficiency issues. Herein, tubular and preferentially oriented CHA-type SAPO-34 membranes with controllable thickness of 0.3–2.5 μm are prepared by a gel-less method with few liquid wastes. The membrane synthesis has a good reproducibility and high efficiency. Perpendicular, ordered and short nanochannels in the SAPO-34 membrane supply the fast path for CO₂ permeation. The highly-oriented SAPO-34 membrane displays CO₂ permeances as high as 1.0 × 10^-5 mol(m² s Pa)^-1 and CO₂/CH₄ and CO₂/N₂ selectivities of 129 and 29, respectively, in the CO₂/CH₄ and CO₂/N₂ separation at 0.2 MPa pressure drop and 298 K. Such super-permeable SAPO-34 membrane prepared by simple and gel-less method is attractive for highly efficient CO₂ capture.