Identification of Molecular Transport Mechanisms in Micro-Porous Hydrotalcite–Silica Membrane

Zeolitic Imidazolate Framework Membranes with a High H2 Permeance Fabricated on a Macroporous Support with Novel Spherical Porous Hybrid Materials

“…Comparison of the single and binary H 2 /CO 2 separation performance of the as-prepared ZIF-8 membrane with the published membranes and the upper bound. (Lower case letters represent the single gas permeation performance, while upper case letters represent the binary gas permeation performance. − )…”

Zeolitic imidazolate framework membranes for gas separation: A review of synthesis methods and gas separation performance

“…At present, only small and medium 58 scale membrane units have been deployed due to the difficulty in 59 achieving high permeability and the necessary level of throughput 60 in large-scale industrial units. The materials that have been used to 61 date consist primarily of dense polymeric membranes that exhibit 62 high selectivity but low permeability; the limited performance of 63 such polymeric membranes is well illustrated by Robeson's plot of 64 selectivity versus permeability [2]. Intensive efforts to develop 65 membranes that exceed Robeson's upper bound have been made 66 by searching for appropriate structures and properties of 67 membrane materials.…”

“…Hydrotalcite (HT) materials have been found to adsorb CO 2 928 preferentially in previous studies because of its spectacular affinity 929 for the gas [63][64][65][66][67][68][69][70][71]. It is expected that the performance of ZIF 930 membrane can be improved further by incorporating the 931 precursors of the materials during the membrane synthesis.…”

Applying Alkyl-Chain Surface Functionalizations in Mesoporous Inorganic Structures: Their Impact on Gas Flow and Selectivity Depending on Temperature

“…These membranes are usually built up by coating multiple layers of different pore sizes onto a supporting structure. The support structure is usually macroporous (>50 nm, mostly 1–10 μm), and one or two mesoporous intermediate layers (10–50 nm) are coated on top of it before depositing the final micro- or mesoporous top layer with pores <10 nm. , The dominating gas transport mechanism within each layer is defined by its structural proportions, resulting in viscous flow in the macroporous support ( Kn < 1), and Knudsen diffusion in the mesoporous intermediate layers ( Kn > 1) accompanied by surface diffusion in the top layer ( Kn > 10). − The transition between the different transport mechanisms is fluid, but under normal conditions (ambient pressure and room temperature), viscous flow can be neglected in pores smaller than 50 nm, and surface diffusion can be neglected in pores larger than 10 nm.…”