The well-cross-linked
ZIF-67 membranes with a thickness of ca.
3 μm were fabricated using α-Al2O3-supported cobalt nanosheets layer (Co-NSL) as an inorganic surface
modifier. During the formation of ZIF-67 membranes, Co-NSL served
as nucleation centers and cobalt source. Single-gas permeation experiments
indicated that the synthesized ZIF-67 membranes showed satisfactory
molecular sieving properties, with their H2 permeance reaching
1.48 × 10–6 mol s–1 m–2 Pa–1. The corresponding ideal separation
factors of H2 over CO2, N2, and CH4 were 16.8, 16.5, and 18.0, respectively. After treatment
with ethylenediamine, the amine-modified ZIF-67 membranes exhibited
satisfactory hydrogen permeance with a high ideal separation factor
of 30.0 for H2/CO2. Compared with the available
metal-organic framework (MOF) membranes in the literature, the use
of Co-NSL as an inorganic surface modifier and the postsynthetic amine
modification ensured the formation of thin and stable ZIF-67 membranes
with grafted −NH2 groups, leading to satisfactory
hydrogen permeances with much enhanced H2/CO2 separation factors.