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

Abstract

An original synthesis strategy for tubular zeolitic imidazolate framework (ZIF) membranes was developed by the deposition of a novel porous amorphous hybrid material prepared by 3-isocyanatopropyltrimethoxysilane (IPTMS) and ZIF-8 crystals onto a coarse macroporous α-Al2O3 tubular support. This porous amorphous hybrid material (ZIF-8-IPTMS) not only strongly adhered to the support but also repaired the defects to make the support surface smooth due to the abundant hydroxyl groups and the appropriate particle size. Using this synthesis strategy, we successfully prepared a high-quality ZIF-8 membrane on an inorganic α-Al2O3 tubular support via the sufficient heterogeneous nucleation sites provided by the amino groups of ZIF-8-IPTMS. This ZIF-8 membrane with an ultrathin thickness of approximately 0.9 μm was prepared, and its ideal H2/CO2 selectivity increased as the temperature increased. The membrane exhibited a competitive selectivity of 13.8 with a remarkably high H2 permeance of 1.46 × 10–5 mol·m–2·s–1·Pa–1 at 90 °C and 0.1 MPa. H2/CO2 binary gas permeation measurements indicated a separation factor of 9.2, and the H2 permeance was maintained at 0.83 × 10–5 mol·m–2·s–1·Pa–1 at 90 °C and 0.1 MPa. This synthesis strategy was also suitable to fabricate ZIF-67 membranes. The ZIF-67 membrane with a thickness of approximately 1.2 μm exhibited a H2/CO2 ideal selectivity of 5.3 and maintained a high H2 permeance of 1.06 × 10–5 mol·m–2·s–1·Pa–1 at 35 °C and 0.1 MPa.

Tuning the Transport Properties of Gases in Porous Graphene Membranes with Controlled Pore Size and Thickness

“…By depositing 100 nm of Au, we were able to achieve an exceptional H 2 /CO 2 separation factor of 31.3 at H 2 permeance of 2.23 × 10 5 GPU permeance (Table S2, Supporting Information), which is the highest value reported to date at this permeance range. [ 14,28,33–44 ] Considering that more than 90% of H 2 is produced via steam reforming process, the H 2 /CO 2 separation is also economically very important. [ 45 ] Notably, this is the first demonstration of a large number of pores on the graphene surface with pore sizes below 3 nm for gas‐separation applications.…”

“…H 2 /CO 2 separation performance of Au‐coated double‐layer graphene membranes compared to graphene oxide (GO), [ 9,10 ] PG, [ 8 ] polyimide–PG membrane (PI–PGM), [ 28 ] carbon molecular‐sieve membranes (CMS), [ 34 ] polybenzimidazole–20% polymer of intrinsic microporosity (PBI–PIM), [ 41 ] graphene/nanoporous carbon film/multiwalled carbon nanotubes (graphene/NPC/MWNT) membrane, [ 14 ] graphene/nickel microislands (G/Ni‐600‐150), [ 29 ] graphene on polished anodic aluminum oxide (G/AAO), [ 26 ] metal–organic framework (MOF), [ 40 ] zeolitic imidiazole framework (ZIF), [ 38 ] Mobil‐5 zeolite (MFI‐Z), [ 35 ] silica, [ 39,42,43 ] and γ‐alumina [ 36,37 ] membranes. (Table S2, Supporting Information).…”

Ultrathin porous amine-based solid adsorbent incorporated zeolitic imidazolate framework-8 membrane for gas separation

“…2a , ZIF-8-IPTMS possessed a spherical morphology, which is consistent with our previous research. 34 SEM analysis was also conducted for ZIF-8-IPTMS-3N-APS prepared by modifying ZIF-8-IPTMS with various volume concentrations of 3N-APS amine compounds, and the images are shown in Fig. 2b–d .…”

“…ZIF-8-IPTMS was synthesized using ZIF-8 crystals and IPTMS silane coupling agents based on the procedures reported in our previous work. 34 In a typical preparation process, ZIF-8 (0.1 g), IPTMS (1 g), and DI water (100 g) were first incorporated into a round-bottom flask. After which, the mixture was heated at 110 °C for 1 h in an oil bath with a reflux condenser.…”

“…It is worth mentioning that ZIF-8-3-isocyanatopropyltrimethoxysilane (IPTMS) hybrid materials have recently been demonstrated for the fabrication of an ultrathin ZIF-8 membrane and the adhesion between the ZIF-8 membrane and the substrate was strengthened. 34 In addition, the porous ZIF-8-IPTMS is highly suitable for use as a raw porous support for the preparation of class 2 solid adsorbents owing to the high hydroxyl group content on the surface, which act as reaction sites for the grafting of amines. As such, the as-prepared class 2 solid adsorbent is expected to serve as a multifunctional deposition layer during the fabrication of ZIF-8 membranes.…”