A new zeolitic hydroxymethylimidazolate material and its use in mixed matrix membranes based on 6FDA-DAM for gas separation

Abstract

The new ZIF named UZAR-S13 is formed by Zn 2+ and 4(5)-(hydroxymethyl)imidazolate. UZAR-S13 has two distinct phases according to SEM and XRD: amorphous spheres and sheet crystals. UZAR-S13 and byproducts, with no N 2 adsorption, rendered a notable CO 2 uptake (up to 3.8 mmol g-1 at 30 bar and 0 °C), approaching values of known ZIFs. The most promising materials were included as fillers in mixed matrix membranes based on copolyimide 6FDA-DAM to study the separation of CO 2 /CH 4 , CO 2 /N 2 , H 2 /CO 2 and H 2 /CH 4. The pore blocking hindered the gas flow of bulky molecules (CH 4 , N 2 and CO 2). The high CO 2 adsorption on sheet crystals also contributed to the decrease in the permeability of CH 4 , N 2 and CO 2 , giving poor selectivities. In contrast, the MMMs improved both the H 2 /CH 4 selectivity (8.9-12.7 vs. 7.2) and permeability of H 2 (544-597 vs. 505 Barrer) of the bare 6FDA-DAM membrane. This emphasizes the potential application of the fillers in the separation by molecular sieving of gas mixtures without CO 2 .

Enhanced gas separation performance of 6FDA-DAM based mixed matrix membranes by incorporating MOF UiO-66 and its derivatives

“…He as sweep gas at 1 cm 3 (STP)•min −1 was used and controlled using an additional mass flow controller. The permeation module is as described elsewhere [12]. The permeate compositions were analyzed online by an Agilent 3000A micro-GC equipped with a thermal conductivity detector.…”

Mixed Matrix Membrane Based on Cross-Linked Poly[(ethylene glycol) methacrylate] and Metal–Organic Framework for Efficient Separation of Carbon Dioxide and Methane

“…A variety of fillers including silica, zeolites, graphene oxide, carbon nanotube, nanoparticles, frameworks, and porous organic cages as well as covalent and metal–organic frameworks (COFs and MOFs) have already been tested. − MOFs are excellent fillers due to their crystalline characters with well-defined chemistry, large surface areas, and controlled porosity. − MOF chemistry also facilitates interfacial interaction with polymeric matrix and enhances resistance to plasticization, thus further improving the membrane performance. , Particularly, zirconium­(IV)–carboxylate MOFs (Zr-MOFs) have emerged in membrane technologies as the inorganic fillers of choice due to their exceptional chemical and thermal stability arising from the strong coordination bonds between the “hard-acid”–“hard-base” interactions between the Zr­(IV) atoms and carboxylate oxygens. − The typical Zr-MOFs include UiO-66 and UiO-66-NH 2 that exhibit a good performance in CO 2 separation. ,,− …”

Boosting gas separation performance and suppressing the physical aging of polymers of intrinsic microporosity (PIM-1) by nanomaterial blending

“…For the porous fillers, the effects are primarily related to their structures and pore sizes, acting as a molecular sieve and separating the permeating gases according to their molecular shapes and kinetic sizes. Due to their precise apertures, MMMs with porous fillers usually exhibit high permeability and selectivity, i.e., the addition of Zr-based MOFs [29,86] and Zn-based MOFs [87,88] in 6FDA-based polyimides. For ease of understanding, a schematic illustration is presented in Figure 5Error!…”

“…Zeolitic imidazolate frameworks (ZIFs), a subclass of MOFs, are constructed of imidazolate (im) anionic organic ligands tetrahedrally coordinated by transition metals (M). ZIF-8, the best-known ZIF, comprised of [Zn(mim)2]•nG (mim = 2-methylimidazole, G = guest) crystallites (see Figure 8(a)), possess the zeolite analogous O-Si-O sodalite topology (SOD), resulting in the M-im-M bridges being at 145° [123], thus giving them highly stable permanent pore apertures and excellent gas separation improvement in many polymer membranes [86,87,124]. Bushell et al [71] reported the use of nano-ZIF-8 (ABET = 1,300 m 2 ·g -1 ; average size of ~50 nm) into PIM-1.…”