Synthesis of ZIF‐93/11 Hybrid Nanoparticles via Post‐Synthetic Modification of ZIF‐93 and Their Use for H₂/CO₂ Separation

Abstract

The present work shows the synthesis of nano-sized hybrid zeolitic imidazolate frameworks (ZIFs) with the rho topology based on a mixture of the linkers benzimidazole (bIm) and 4-methyl-5-imidazolecarboxaldehyde (4-m-5-ica). The hybrid ZIF was obtained by post-synthetic modification of ZIF-93 in a bIm solution. The use of different solvents, MeOH and N,N-dimethylacetamide (DMAc), and reaction times led to differences in the quantity of bIm incorporated to the framework, from 7.4 to 23 % according to solution-state NMR spectroscopy. XPS analysis showed that the mixture of linkers was also present at the surface of the particles. The inclusion of bIm to the ZIF-93 nanoparticles improved the thermal stability of the framework and also increased the hydrophobicity according to water adsorption results. N and CO adsorption experiments revealed that the hybrid material has an intermediate adsorption capacity, between those of ZIF-93 and ZIF-11. Finally, ZIF-93/11 hybrid materials were applied as fillers in polybenzimidazole (PBI) mixed matrix membranes (MMMs). These MMMs were used for H /CO separation (at 180 °C) reaching values of 207 Barrer of H and a H /CO selectivity of 7.7 that clearly surpassed the Robeson upper bound (corrected for this temperature).

Tuning of Nano-Based Materials for Embedding Into Low-Permeability Polyimides for a Featured Gas Separation

“…Nowadays, one of the current approaches in MMM preparation also comprises the simultaneous use of two different dispersed phases (i.e., fillers) into the polymer matrix (Castarlenas et al, 2017;Echaide-Gorriz et al, 2017;Sanchez-Lainez et al, 2018), which has brought two positive effects: the enhanced synergistic separation performance and improvement on dispersing homogenously the filling materials. For example, the synergistic effect of combining a MOF (Al-MIL-53-NH 2 ) and ordered mesoporous silica with a MCM-41-type structure in MMMS was studied by Valero et al (2014), who successfully embedded both materials into the commercial Matrimid R .…”

“…On the other hand, valuable insights have been obtained by tuning other materials not commonly used in GS applications, like MOF ZIF-93. For example, in Prof. Coronas' group, the postsynthetic modification of ZIF-93 has been performed and then evaluated in other types of polymers (e.g., polybenzimidazole), but its incorporation in low-permeability PIs has not been reported yet (Sanchez-Lainez et al, 2018). Moreover, the possible tuning of sod-ZMOF, as a highly adsorptive CO 2 material, could provide better selective properties to the Matrimid R -based MMMs since it has provided in single-gas permeation increases for CH 4 and CO 2 permeabilities with minimal changes in selectivity (Kiliç et al, 2015).…”

Molecular Modeling Investigations of Sorption and Diffusion of Small Molecules in Glassy Polymers

“…Development and implementation of efficient, hybrid and adaptive resolution multiscale molecular simulation methods [125,292,293,294,295,296,297,298] may in many cases be necessary for the systematic study of microscopic behavior at the interfaces in composite materials and mixed matrix membranes and for further advancement of the materials-by-design target. In this direction it would be worthwhile to study many technologically and commercially important polymer-based nanocomposite membranes [299,300,301,302,303,304,305] such as Matrimid-based ones [306,307,308], incorporating a number of potential inorganic fillers. Multiscale molecular simulation strategies in the area of next generation multicomponent nanostructured materials are important in identifying how the fillers can be tailored towards an optimum selectivity and permeability behavior, investigating a number of crucial factors such as the effects of the size and the dispersity of the fillers and nanoparticles in the terminal properties as well as the influence of the morphology and surface treatment on the behavior and stability of the multicomponent membrane.…”

Green Preparation of Thin Films of Polybenzimidazole on Flat and Hollow Fiber Supports: Application to Hydrogen Separation

“…This work, however, intends to create a new methodology to demonstrate that it is possible to handle m‐PBI for the preparation of membranes with ethanol, a solvent quite different to those traditionally used. There are multiple techniques for improving the gas separation performance of polymeric membranes (crosslinking, [18,19] blending with other polymers, [20,21] mixed matrix membranes, [16,17,22–26] etc.) that can be used to enhance that of m‐PBI films.…”