Hollow Silica‐Based Porous Liquids Functionalized Mixed Matrix Membranes for CO₂ Capture

Abstract

Porous liquids (PLs) are a newly emerging type of porous materials with empty cavities and tailed functionalities, demonstrating great potential in gas capture. However, PLs used as fillers of mixed matrix membranes (MMMs) are seldom reported till now. Herein, MMMs for CO2 selective separation were prepared by incorporating hollow silica PLs into Pebax‐1657 matrix. As expected, the liquid‐like property of PLs renders excellent filler dispersion. Besides, the hollow cavities construct fast permeation diffusion channels, reducing trans‐membrane permeation resistance. More importantly, CO2‐philic moieties of PLs lead to superior CO2 selective permeation. Therefore, the as‐prepared MMM exhibited a CO2 permeability up to 229.5 Barrer with a CO2/N2 selectivity up to 71.7 (241.9 % and 90.2 % increment than those of pure Pebex‐1657 membrane, respectively), surpassing the 2008 Robeson upper bound. Finally, molecular simulation was applied to verify the improved interaction between gas molecules and membrane by analyzing interaction parameters. Our work underlines the feasibility and importance of porous liquids to design advanced fillers in MMMs, which makes great promise for CO2 capture.

Porous liquids – the future is looking emptier

“…Porous liquids can also be included as a component in a MMM, for example, a HS nanosphere based porous liquid was incorporated into a polymer matrix at up to 25 wt% in order to enhance the CO 2 permeability and CO 2 /N 2 selectivity. 75 The use of the porous liquid was required in this case, as unmodified silica spheres agglomerated on preparation as a membrane.…”

“…74 GCMC have been used to examine CH 4 solubility in a POCbased type II porous liquid, 26 as well as identify CO 2 selective sites in a MOF-based type III porous liquid, 35 and a hollow silica type I porous liquid. 75 GCMC isotherms have also been compared with experiment to verify that PDMS chains within the MIL-101(Cr) cavity disrupted the gas uptake process by calculating the isotherm of a model featuring PDMS manually placed within the MOF pores. 48 The detailed information offered by DFT provides additional insight into the mechanism of gas uptake.…”

Construction of a Hollow SiO2-Based Porous Liquid Based on Polydopamine and Its Application in CO2 Separation of Membranes

“…We referred to the drop-casting method in the previous report to prepare MMMs. 29 Pebax-1657 particles were dissolved in a mixed solution of ethanol/H 2 O (75/25 by weight) and refluxed at 80 °C for 12 h to obtain a 4 wt % Pebax-1657 solution. Then, the PL as a filler was added to 4 mL of the preprepared 4 wt % Pebax-1657 solution, stirred at room temperature overnight, poured into an ultraflat Petri dish, left for 24 h, and then dried at 45 °C for at least 48 h to completely remove the residual solvent.…”

“…41 The absorption peaks of the MMMs prepared with the PL are roughly the same as those of the pure Pebax-1657 membrane, and no new characteristic peaks appeared, indicating that P-PL-X maintains the chemical structure of the Pebax matrix, whereas there is no chemical interaction between the Pebax matrix and the PL. 20,29 The crystalline properties of the membranes were investigated using their XRD patterns. As shown in Figure 5b, the sharp peak at 2θ = 26.5°is attributed to the crystalline region of the polyamide block (PA6) formed by interchain hydrogen bonding in Pebax-1657.…”

“…More importantly, the uniform dispersion of PL in the Pebax matrix is of great significance for the formation of defect-free membranes. 29 The surface roughness parameters R a and R q were also used to calculate the membrane roughness R a /R q , R a /R q of P-PL-20 and P-HS-1 and were obtained as 0.82 and 0.77, respectively. Greater roughness means that the membrane has a larger contact area with gas to a certain extent, which further reveals that PL as a filler will be beneficial to improving the separation performance of the membrane.…”