CO₂/N₂ and O₂/N₂ Separation Using Mixed‐Matrix Membranes with MOF‐74 Nanocrystals Synthesized Via Microwave Reactions

Abstract

Due to their large surface areas and unique gas adsorption properties, mixed‐matrix membranes (MMMs) with metal–organic frameworks (MOFs) have been extensively studied in relation to various gas separations. In the present paper, we report the quick synthesis of MOF‐74 (M = Mg, Mn, Co, Ni) nanocrystals by microwave reactions and the fabrication of MMMs for use in CO2/N2 and O2/N2 separation. The scanning electron microscopy and energy dispersive X‐ray spectroscopy analysis revealed the homogenous distribution of the MOF‐74 nanocrystals within the polydimethylsiloxane (PDMS). The single gas permeation experiments showed the enhanced CO2/N2 and O2/N2 selectivity by adding the MOF‐74 nanocrystals to the PDMS. This enhanced CO2/N2 and O2/N2 selectivity may be due to the affinity of CO2 and O2 toward the Lewis acidic sites of the MOF‐74.

Probing growth of metal–organic frameworks with X-ray scattering and vibrational spectroscopy

“…3 are in agreement with literature values obtained from bulk reactions. 15 The PXRD pattern of the MOF microcrystals synthesized on the chip, matches the simulated PXRD pattern well confirming our assertion that we are indeed forming Co-MOF-74 with the same morphology as that obtained under bulk conditions. The SEM image of the crystals formed on the ATR chip shown in the inset of Fig.…”

“…31,32 These peaks match results obtained for Co-MOF-74 from the literature, which are shown as an inset in the figure. 15 The sharp peaks are the only peaks that increase over time, whereas the rest of the broad scattered background emerging from the reagents decreases over time. There are several other tiny peaks corresponding to shorter interatomic distances, which are difficult to trace their kinetics.…”

“…The process of crystallization includes a multitude of steps such as forming monomers and a bulk crystal lattice, and the rates for nucleation and growth are greatly affected by the lability of the metal ion. 9,11–13 We have chosen to study the nucleation and growth of Co-MOF-74, which is also known as CPO-27-Co or Co 2 (dobdc) (dobdc 4− =2,5-dioxido-1,4-benzenedicarboxylate), a system that has been studied under bulk reaction conditions 14,15 (Fig. 1).…”

Polydimethylsiloxane/Magnesium Oxide Nanosheet Mixed Matrix Membrane for CO2 Separation Application

“…According to Li et al [ 35 ], such 2D porous nanosheet configurations having high surface area, open pore structure, and well-dispersed fine MgO nanoparticles are favourable for CO 2 gas sorption. Additionally, MgO could potentially facilitate CO 2 transport through the membrane via Lewis acid–base mechanism, as explained in previous literature [ 36 , 37 , 38 ], which may contribute to the improvement of the gas separation performance. Secondly, as far as the fabrication of ultra-thin defect-free asymmetric membrane is concerned, they are really challenging, as they have many factors to be considered [ 39 ].…”

Fast catalytic transfer hydrogenation of phenol to cyclohexanol over urea modified Ni@CN nanoparticles

“…40–42 They have been applied in many fields owing to their large specific surface area, large apertures and excellent stability, such as catalysis, 17,43–45 electrode materials, 46–48 adsorbents, 49,50 storage and separation of mixed gases. 51,52 In addition, one of the most important applications of MOF materials is that they could be used as sacrificial templates to synthesize carbon-based materials through direct pyrolysis under an inert atmosphere. 53–55 The resulting composite materials possessed large specific surface areas, high porosity, high metal loadings and well-defined structures, achieving excellent catalytic performance.…”