Delayed Linker Addition (DLA) Synthesis for Hybrid SOD ZIFs with Unsubstituted Imidazolate Linkers for Propylene/Propane and n‐Butane/i‐Butane Separations

Abstract

We present anovel synthesis strategy termed delayed linker addition (DLA) to synthesize hybrid zeolitic-imidazolate frameworks containing unsubstituted imidazolate linkers (Im) with SOD topology (hereafter termed Im/ZIF-8). Im linker incorporation can create larger voids and apertures, which are important properties for gas storage and separation. To date,there have been only ahandful of reports of Im linkers incorporated into ZIF-8 frameworks,t ypically requiring arduous and complicated post synthesis approaches.D LA, as reported here,i sasimple one-step synthesis strategy allowing high incorporation of Im linker into the ZIF-8 framework while still retaining its SOD topology.W ef abricated mixedmatrix membranes (MMMs) with 6FDA-DAM polymer and Im/ZIF-8 obtained via DLA as af iller.T he Im/ZIF-8containing MMMs showed excellent performance for both propylene/propane and n-butane/i-butane separation, displaying permeability and ideal selectivity well abovet he polymer upper bound. Moreover,highly detailed molecular simulations shed light to the aperture sizea nd flexibility response of Im/ ZIF-8 and its improved diffusivity as compared to ZIF-8.

Covalent‐Linking‐Enabled Superior Compatibility of ZIF‐8 Hybrid Membrane for Efficient Propylene Separation

“…[ 47 ] It is worth mentioning that good ZIF‐PIM compatibility and porous PIM‐1 endow ZIF‐8 86 ‐CN 14 @tPIM‐1 with top‐class selectivity among reported ZIF‐8 MMMs and most advanced permeability over the others (Figure 5c). [ 18–31 ] Another comparison with ZIF‐8 polycrystalline membranes shows that ZIF‐8 86 ‐CN 14 @tPIM‐1 has superior C 3 H 6 permeability and moderate competence in C 3 H 6 /C 3 H 8 selectivity (Table S5, Supporting Information). The selectivity–permeability points lie well above the latest upper bound, [ 48 ] and C 3 H 6 /C 3 H 8 selectivity (23.4) and C 3 H 8 permeance (≈22 GPU) are of the industrial interest for C 3 H 6 /C 3 H 8 separation from purge gas or olefin cracker according to selectivity and permeance requirements of 6–10/15–20 and 20–40 GPU.…”

“…[ 12 ] Thus, ZIF‐8 has been explored as the filler to fabricate MMMs for this purpose. [ 13–31 ] In ZIF‐8 MMMs, the C 3 H 6 /C 3 H 8 selectivity is kinetically controlled by the ZIF‐8 fillers themselves. Thus, the interface engineering between ZIF‐8 and polymer is of paramount importance for tailoring the membrane selectivity because few phase‐boundary defects can severely suppress the selectivity for C 3 H 6 over C 3 H 8 .…”

“…[ 15–27 ] Although the selectivity was increased, the permeability was largely sacrificed; however, high permeability is very demanding in membrane propylene separation. [ 32 ] ZIF‐8 functionalization is another method to modify the ZIF–polymer interfaces in MMMs; however, few studies have been reported on this phenomenon, [ 28–31 ] probably due to metal saturated coordination and ligand chemical inertness in the ZIF‐8 structure. Recent attempts have achieved success in the preparation of mixed‐ligand ZIF‐8, rendering further functionalization possible.…”

A Hybrid Zeolite Membrane-Based Breakthrough for Simultaneous CO2 Capture and CH4 Upgrading from Biogas

“…Membrane-based separation and purification processes allow more compact and energy-efficient operations in comparison with conventional energy-intensive methods such as distillation and recrystallization. , Concomitantly, this energy-efficient process is advantageous for low environmental pollution because the current global temperature and sea level are monotonically rising and, more crucially, local climate change is proceeding in an unpredictable way due to CO 2 emissions from the usage of fossil fuels. , Therefore, for a cost-effective and eco-friendly process, a membrane can be applied to the separation fields in the refinery/petrochemical industries, carbon capture and storage, and biogas/natural gas upgrading. ,− …”

Data mining for predicting gas diffusivity in zeolitic-imidazolate frameworks (ZIFs)

“…In fact, topology variations would severely obscure our ndings as this is an additional factor, 20,39 which can greatly affect the aperture size as well as the network connectivity and therefore the diffusion of penetrants. 33,40 The design of new variants was driven from the insight gained from our recent works [41][42][43][44][45] regarding the impact of modications on the aperture which bridges the cages (Fig. 1).…”