CO2-philic Membranes Research Articles

Ultrapermeable Gel Membranes Enabling Superior Carbon Capture.

Membrane technology is rapidly gaining broad attraction as a viable alternative for carbon capture to mitigate increasingly severe global warming. Emerging CO2 -philic membranes have become crucial players in efficiently separating CO2 from light gases, leveraging their exceptional solubility-selectivity characteristics. However, economic and widespread deployment is greatly dependent on the boosted performance of advanced membrane materials for carbon capture. Here, we design a unique gel membrane composed of CO2 -philic molecules for accelerating CO2 transportation over other gases for ultrapermeable carbon capture. The molecular design of such soft membranes amalgamates the advantageous traits of augmented permeation akin to liquid membranes and operational stability akin to solid membranes, effectively altering the membrane's free volume characteristics validated by both experiments and molecular dynamics simulation. Surprisingly, gas diffusion through the free-volume-tuned gel membrane undergoes a 9-fold improvement without compromising the separation factor for the superior solubility selectivity of CO2 -philic materials, and CO2 permeability achieves a groundbreaking record of 5608 Barrer surpassing the capabilities of nonfacilitated CO2 separation materials and exceeding the upper bound line established in 2019 even by leading-edge porous polymer materials. Our designed gel membrane can maintain exceptional separation performance during prolonged operation, enabling the unparalleled potential of solubility-selective next-generation materials towards sustainable carbon capture.

Plasma-engineered graphene quantum dot-based nanocomposites as smart CO2-philic membranes with extremely high separation performance

Carbon dioxide (CO2) capture, separation and utilization with membrane-based technologies are important for the development of carbon neutral society. However, conventional membranes are facing the difficulties of energy-consuming fabrication, expensive and toxic chemicals, and low efficient performance. Here, we report the CO2-Philic, optical-active nitrogen-doped graphene quantum dot (NGQD)-embedded polyether-block-amide (Pebax)-based membranes for highly efficient CO2 separation and sensitive on-line CO2 detection. The NGQDs with abundant surface functionalities are synthesized from bioresource chitosan using a customized microplasma process. The plasma-engineered NGQDs with defined zero-dimensional (0D) geometry, surface functional groups and nitrogen dopants can enhance the CO2-philicity for CO2 capture and separation. Moreover, the NGQDs can not only generate the angstrom (Å)-level channels, but also tune the morphologies, pore structures, crystallinities of the nanophases, and functional groups of the Pebax-based membranes, leading to extremely high CO2 separation performance with a 415 Barrer CO2 permeability and a 125 CO2/N2 selectivity. Furthermore, the stable solid-state PL emission of the fabricated GQD@Pebax membranes enables the sensitive on-line monitoring of CO2 concentrations during the CO2 separation. Our work provides an understanding of the CO2 capture and transport with nanomaterials-based composites and a plasma engineering of advanced functional materials for clean energy, environmental and biomedical applications.

Chemical topology molecular engineering of CO2-philic membranes toward highly efficient carbon capture

Membrane gas separation processes represent a crucial platform for achieving carbon neutral climate goals. CO2-philic membranes offer excellent solubility selectivity due to their high affinity, thereby allowing the separation of gas fractions with similar molecular sizes or smaller than CO2 molecules. This level of separation is difficult to achieve with conventional diffusion-dominated separation membranes. However, the gas permeability of PEO membranes is often hampered by dense chain packing and crystallization behavior. To overcome this challenge, we employed a molecular engineering approach to develop a unique PEO membrane with a hyperbranched chemical topology connection. The packing density of the polymer chains was effectively regulated by employing cross-linker molecules with distinct spatial configurations, while the free volume fraction was successfully reinforced. This unique molecular engineering strategy led to the creation of a PEO membrane exhibiting superior performance that surpassed the limit of the 2019 upper-bound line. This work demonstrated a molecular design strategy for the precise control of structural attributes in crosslinked PEO networks, offering an alternative solution for developing CO2 capture membranes and enabling further opportunities for rational membrane material design.

One-Step Synthesis of Structurally Stable CO2-Philic Membranes with Ultra-High PEO Loading for Enhanced Carbon Capture

Membrane technology has been considered a promising strategy for carbon capture to mitigate the effects of increasing atmospheric CO 2 levels because CO 2 -philic membranes have demonstrated significant application potential, especially, for CO 2 /light gas separation. In this regard, poly(ethylene oxide) (PEO), which is a representative CO 2 -philic material, has attracted extensive research attention owing to its specific dipole–quadrupole interaction with CO 2 . Herein, we report a facile one-step synthesis protocol via the in situ polymerization of highly flexible polyethylene glycol to overcome the limitations of PEO, including high crystallinity and poor mechanical strength. The robust structure derived from intricate entanglements between short PEO chains and the polymer matrix enables an extremely high loading of linear polyethylene glycol (up to 90 wt%). Consequently, the separation performance easily surpasses the upper-bound limit. Moreover, the high structural stability allows for the concurrent increase of CO 2 permeability and CO 2 /light gas selectivity at high feed pressure (up to 20 bar). This study provides a promising strategy to simultaneously improve the toughness and gas separation properties of all-polymeric membranes, demonstrating significant potential for industrial carbon capture and gas purification.

CO2-philic mixed matrix membranes based on low-molecular-weight polyethylene glycol and porous organic polymers

Membrane-based separation processes can efficiently capture CO2 and reduce energy consumption. However, the synthesis of a CO2-philic material which can replace traditional gas separation materials for advanced membrane separation faces numerous challenges. In this paper, we report the incorporation of porous organic polymers (POPs) and low-molecular-weight polyethylene glycol (PEG 400) into Pebax 1657 for the fabrication of a CO2-philic mixed matrix membrane for CO2 capture. The POPs, which contained azo bonds and phenolic hydroxyl groups, exhibited CO2-philic and N2-phobic properties. PEG 400, which possesses ethylene oxide (EO) units with a polar ether group, enhanced the CO2 permeability and CO2/N2 selectivity. This CO2-philic membrane showed CO2 permeability of 392 Barrer and CO2/N2 selectivity of 112, which surpassed the upper bound (2019). This membrane could be a widely applicable tool for improving CO2 capture with advanced membranes.

Penetrating chains mimicking plant root branching to build mechanically robust, ultra-stable CO2-philic membranes for superior carbon capture

Branched plant root mimicking PEO chains can simultaneously increase the gas separation performance, membrane stability and mechanical strength of CO2-philic membranes for superior carbon capture.

Nanoporous framework “reservoir” maximizing low-molecular-weight enhancer impregnation into CO2-philic membranes for highly-efficient CO2 capture

Although membrane technology for CO2 capture is promising for environmental and energy remediation, the membrane performance should be improved greatly for realizing the practical applications. Herein, a new dual-incentive strategy by utilizing the synergistic effect of nanoporous framework and low molecular weight poly (ethylene glycol) (PEG) impregnation has been designed to construct a high-efficiency forced impregnated hybrid membranes (FIHMs) for CO2 capture. Amino functional polyhedral oligomeric silsesquioxanes (POSS-NH2) served as nanoporous “reservoir” for the significantly enhanced impregnation of low-molecular-weight PEG in the cross-linked membrane. The incorporated nanoporous POSS-NH2 particles in membranes can not only promote gas transportation but increase the loading of low-molecular-weight PEG. The basic physicochemical and gas transport properties of various FIHMs were examined. Remarkably, optimal CO2 permeability of FIHM with 180 wt% poly (ethylene glycol) dimethyl ether (PEGDME-500) loading can reach as high as 1566.8 Barrer, which demonstrates unprecedented 983% increment as compared with that of original cross-linked Poly (ethylene oxide) (PEO) membrane. At the same time, CO2/N2 selectivity was kept the similar level and CO2/H2 selectivity was improved. The outstanding CO2 capture performance of our FIHM membranes have been verified by comparing with the 2008 Robeson's “Upper Bound” Line. The dual-incentive strategy proposed in this study can stimulate the advanced membrane research by rationally structural design and push forward the CO2 capture membrane to industrial applications.

Ionic Liquid Selectively Facilitates CO2 Transport through Graphene Oxide Membrane.

Membrane separation of CO2 from H2, N2, or CH4 has economic benefits. However, the trade-off between selectivity and permanence in membrane separation is challenging. Here, we prepared a high-performance CO2-philic membrane by confining the [BMIM][BF4] ionic liquid to the nanochannels in a laminated graphene oxide membrane. Nanoconfinement causes the [BMIM][BF4] cations and anions to stratify. The layered anions facilitate CO2 transportation with a permeance of 68.5 GPU. The CO2/H2, CO2/CH4, and CO2/N2 selectivities are 24, 234, and 382, respectively, which are up to 7 times higher than that of GO-based membranes and superior to the 2008 Robeson upper bound. Additionally, the resultant membrane has a high-temperature resistance, long-term durability, and high-pressure stability, indicating its great potential for CO2 separation applications. Nanoconfining an ionic liquid into the two-dimensional nanochannels of a laminated membrane is a promising gas separation method and a nice system for investigating ionic liquid behavior in nanoconfined environments.

Poly(amide-12-b-ethylene oxide)/glycerol triacetate blend membranes for CO2 separation

In this paper, CO2-philic membranes are prepared with poly(amide-12-b-ethylene oxide) (Pebax1074) and glycerol triacetate (GTA) by polymer blending, which show excellent compatibility for different GTA compositions. The additive GTA into Pebax1074 matrix can improve the chain mobility, induce high CO2-philicity and decrease membrane crystallinity. With the increase of GTA mass content from 0 to 80wt%, CO2 permeability increases from ∼135 to ∼1800Barrer, and CO2/H2 ideal selectivity also increases from 10 to 19. For Pebax1074/GTA blend membranes, the threshold mass content of GTA (C*) which corresponds to the rapid increase of gas permeability is about 40wt%. When GTA mass content is not more than C* (40wt%), the gas permeation properties are mainly dominated by Pebax1074. But for Pebax1074/GTA blend membranes with GTA mass content above C* (40wt%), their gas permeabilities and CO2/light gas selectivities both change dramatically, which are mainly influenced by GTA. These membranes show excellent separation performance for CO2/N2 and CO2/H2, especially for CO2/H2 separation.

Design, synthesis, characterization and optimization of PTT- b-PEO copolymers: A new membrane material for CO 2 separation

The design and synthesis of polymers with well-defined properties (tailor-made) are reported in this paper. The work focuses on the design of experiments, synthesis and characterization of poly(trimethylene terephthalate)- block-poly(ethylene oxide) (PTT- b-PEO) copolymers as CO 2-philic membrane materials. The statistical analysis of experimental data, data fitting to mathematical models, as well as the optimization of CO 2 permeability is discussed. By these means we synthesized optimal materials with promising CO 2 separation performance (CO 2 permeability = 183–200 Barrer and CO 2/N 2 selectivity >50); they are also promising because the synthesis is simple, highly reproducible and might be scalable for producing on large volumes. Thus, these new and tailored polymers might have potential applications as membrane material for CO 2-capture.

CO2-Philic Polymer Membrane with Extremely High Separation Performance

Polymeric membranes are attractive for CO2 separation and concentration from different gas streams because of their versatility and energy efficiency; they can compete with, and they may even replace, traditional absorption processes. Here we describe a simple and powerful method for developing nanostructured and CO2-philic polymer membranes for CO2 separation. A poly(ethylene oxide)−poly(butylene terephthalate) multiblock copolymer is used as membrane material. Smart additives such as polyethylene glycol dibutyl ether are incorporated as spacers or fillers for producing nanostructured materials. The addition of these specific additives produces CO2-philic membranes and increases the CO2 permeability (750 barrer) up to five-fold without the loss of selectivity. The membranes present outstanding performance for CO2 separation, and the measured CO2 flux is extremely high (>2 m3 m−2 h−1 bar−1) with selectivity over H2 and N2 of 10 and 40, respectively, making them attractive for CO2 capture.