Highly Ordered Nanochannels in a Nanosheet‐Directed Thin Zeolite Nanofilm for Precise and Fast CO₂ Separation

Abstract

Precise molecular and ion separations depend largely on the size and uniformity of the nanochannels in a defect-free microporous nanofilm. Ordered and perpendicular nanochannels with uniform pore size are assembled into a continuous and defect-free film by a "gel nuclei-less" route. The ultrathin (<50 nm) zeolite nanosheets seeding layer induces the formation of defectfree zeolite nanofilms (500-800 nm) with preferential [100] orientation well-aligned to the transport pathway. The large-area and thin silicoaluminophosphate-34 (SAPO-34) nanofilm consisting of uniform and straight nanochannels shows a milestone CO 2 permeance of ≈1.0 × 10 −5 mol (m 2 s Pa) −1 and high CO 2 /CH 4 and CO 2 /N 2 selectivities of 135 and 41 in equimolar binary mixtures at room temperature and 0.2 MPa feed pressure, respectively. These results suggest that highly oriented and thin SAPO-34 nanofilms prepared from nanosheets might have great potential for CO 2 capture from natural gas, biogas, and flue gas.

Porous Nanoarchitectures of Nonprecious Metal Borides: From Controlled Synthesis to Heterogeneous Catalyst Applications

“…, nanosheet) porous metals have superior conductivity and more exposed surface atoms, which greatly increase the utilization efficiencies of materials . Highly ordered mesoporous materials are highly efficient for establishing the structure–performance relationship. , Specifically, uniform distribution of sizes, shapes, and volumes in the ordered mesoporous materials can selectively adsorb/separate guest molecules with specific sizes, leading to superior catalytic properties. Considering the case of CO 2 conversion as an example, the selection of an ordered porous structure in mesoporous metal oxides was related to the activity and distribution of products .…”

Recent Progress of SAPO-34 Zeolite Membranes for CO2 Separation: A Review

“…More cycles of healing via VAD caused a decrease in the membrane performance, indicating the low CO 2 permeance and selectivity of BTESE. Recently, Wang et al [ 115 ] fabricated highly oriented SAPO-34 nanofilms with ordered channels (prepared by the gel-nuclei-less method) on α-Al 2 O 3 tubes via a secondary growth route. The superior performance was related to the large and continuous area of the nanofilms, which provided a fast permeating and CO 2 selective route.…”

Pebax and CMC@MXene-Based Mixed Matrix Membrane with High Mechanical Strength for the Highly Efficient Capture of CO2

“…To overcome the trade-off effect of the conventional one-component polymer membranes in permeability (permeance) and selectivity during the separation process, the mixed matrix membranes (MMMs) composed of matrix and fillers have emerged as a state-of-the-art approach to expand the potential applications of traditional polymers in gas separation. , The polymer matrix in MMMS possess the advantages of high mechanical strength and easy processability; meanwhile, the addition of some inorganic fillers can improve the separation and permeation properties in MMMs. The most popular inorganic materials used in mixed matrix membrane are graphene oxide, metal–organic frameworks, ,− molybdenum disulfide, and MXene. , Among them, 2D MXene has attracted much attention in the field of membrane separation due to its special characteristics of single atomic thickness, long-term dispersion, chemical stability, and molecular filtration abilities. − The inorganic filler MXene plays a crucial role in MMMs, which can significantly improve the separation performance of the MMMs, such as (1) by exploiting the 2D morphology and narrow interlayer spacing for molecular size exclusion, (2) prolonging the diffusion path of solutes to improve selectivity, (3) tuning surface chemistry to facilitate molecular transport, and (4) modification of polymer chains to improve the mechanical and separation properties of fillers . But when the content of MXene in the matrix is increased, the gas molecules’ separation performance is decreased.…”