Matrix Membranes For CO2 Separation Research Articles

Defect-Engineered Metal-Organic Framework/Polyimide Mixed Matrix Membrane for CO2 Separation.

Anovel defect-engineered MOF (quasi ZrFum or Q-ZrFum) was synthesized via a controlled thermal deligandation process and incorporated into a CO2-philic 6FDA-durene polyimide (PI) matrix to form Q-ZrFum loaded MMMs. Defect-engineered MOFs and fabricated MMMs were investigated in terms of their characteristic properties and separation performance. The incorporation of defects into the MOF structure increases the pore size and provides unsaturated active metal sites that positively affect CO2 molecule transport. After the deligandation process, the interfacial compatibility between the Q-ZrFum particles and the PI matrix increases, which improves the mechanical strength of Q-ZrFum loaded membranes. MMM containing 5 wt.% of defect-engineered Q-ZrFum exhibits excellent CO2 permeability of 1308 Barrer which increased by 99% compared to the pure PI membrane (656 Barrer) at a feed pressure of 2 bar. Moreover, CO2/CH4 and CO2/N2 selectivity reached 44 and 26.6 which increased by about 70 and 16%, respectively. This study emphasizes that defect-engineered MOFs can be promising candidates for use as filler in the preparation of MMMs for the future development of membrane-based gas separation applications.

Integrating two-dimensional MXene fillers into nanocellulose for the fabrication of CO2 separation membranes

To achieve high capability mixed matrix membranes for CO2 separation, it is vital to construct the suitable transport channels to enhance the diffusivity-enabled selectivity as well as an excellent affinity toward target gas molecules to increase the solubility-based selectivity. Herein, composite membranes were constructed by integrating two-dimensional MXene nanosheets into a carboxylated nanocellulose matrix. The carboxyl-rich cellulose interacts with the surface groups of MXene, which contributes to a superior interface compatibility and repairs the non-selective voids. In particular, one-dimensional nanocellulose can intercalate into MXene laminates to regulate the interlayer spacing and suppress the re-stacking of MXenes. The resulting MC-3 membrane (with a MXene loading of 15.4 wt%) possesses the optimal separation performance, bearing a CO2 permeability of 156.7 Barrer with ideal selectivities of 47.8 for CO2/CH4 and 42.6 for CO2/N2. For the mixed gas separation, the MC-3 membrane exhibits separation factors of 48.5 and 55.3 for CO2/N2 and CO2/CH4, respectively. This excellent separation performance is resulted from the enhanced interfacial property, suitable MXene channel size and good CO2-solubility of nanocellulose.

Constructing mixed matrix membranes for CO2 separation based on light lanthanide fluoride nanosheets with mesoporous structure

The incorporation of porous nano-fillers into mixed matrix membranes (MMMs) has a great impact on CO2 separation. In this study, a series of F-Ln (Ln is the Light Lanthanide, Ln = La, Ce, Pr, Nd) nanosheets with mesoporous structure was fabricated as a filler in Pebax®1657 matrix to improve the performance of CO2 separation. F-Ln nanosheets are uniformly distributed in the membrane and the mesoporous structure can construct multiple channels for CO2 fast transport in Pebax/F-Ln MMMs. The pore diameter of nanosheet is in order: F-La > F-Ce > F-Pr > F-Nd, and the smaller pore diameter of nanosheets is beneficial to improve the CO2 separation performance. In humidified conditions, Pebax/F-Nd-6 MMMs show optimum separation performance among MMMs, and the CO2 permeability is up to 1265 Barrer and CO2/CH4 selectivity is 36.7, which are 2.3 times and 1.9 times higher than pure Pebax and approaches 2019 upper bound. Meanwhile, to demonstrate the potential universal applicability of F-Ln nanosheets in CO2 separation, XLPEO/F-Ce MMMs were fabricated to separate CO2/N2 and the performance exceeds the 2019 upper bound. The efficient CO2 separation performance of 2D F-Ln nanosheets with mesoporous structure in membranes reveals the potential application of these nanosheets in industrial CO2 separation.

Investigation of cellulose acetate and ZIF-8 mixed matrix membrane for CO2 separation from model biogas

ABSTRACT The separation of CO2 from the biogas mixtures (CH4/CO2) is essential for biogas upgradation. However, polymer membranes used for CO2 separation exhibit low permeability. Mixed Matrix Membranes (MMMs) incorporating inorganic filler in the polymer enhance CO2 separation. In this work, bio-degradable cellulose acetate (CA) based MMMs with varying filler weight percentages (2–20 wt.%) of ZIF-8 were studied for the separation of CO2 from a model biogas (CH4/CO2) mixture. The MMMs were characterized by analysis of TGA and DSC for thermal stability and FTIR for alteration or formation of any new functional group. FESEM was done to evaluate the dispersion and interaction of ZIF-8 in the CA polymer matrix. Considering the economic aspect, the fabricated MMMs were tested for gas separation performance at reasonably lower feed pressure (1.5, 2 bar). MMM with 5 and 10 wt.% of ZIF-8/ CA MMMs showed the best performance with CO2 permeability of 9.65 Barrer and 9.5 Barrer, approximately two folds as compared to pure CA, and CO2/CH4 selectivity was 10.37 and 15.3. The experimental results were compared with the predicted gas permeation results determined using MMM transport predictive models, and found that the permeabilities were higher than the model predictions.

Preparation and characterization of PPO/ SiO2 mixed matrix membrane for CO2 separation using membrane contactor

This study presents CO2 separation using PPO/SiO2 mixed matrix membranes (MMMs) in a membrane contactor. The non-solvent induced phase separation (NIPS) method was used to prepare flat sheet membranes using a commercial grade of PPO (polyphenylene oxide) polymer and 2-Ethyl-1-hexanol as a non-solvent additive. Mixed matrix membranes were fabricated via two approaches; adding the hydrophobic silica into casting solution (approach 1) and into coagulation bath (approach 2). The results showed that the addition of 2-ethyl-1-hexanol (5wt%) to the casting solution improved the membrane porosity by 74.7% while reducing the contact angle from 106.3 to 95.2°. Water contact angle of prepared MMMs by approaches 1 and 2 were found to be around 117.8 and 142.9°, respectively indicating that silica could enhance the membrane hydrophobicity in both methods. The maximum CO2 absorption flux and removal efficiency were attained about 5.8 × 10−3 (mol.m−2.s−1) and 64.8 % for MMM with 2 wt.% silica in approach 1. Meanwhile, MMM obtained with silica content (2 g.L−1) from approach 2, indicated CO2 flux of 5 × 10−3 (mol.m−2.s−1) and removal efficiency around 55.8 %. The long-term performance of prepared MMMs was evaluated during 20 days of operation. The results confirmed the long term stability of prepared samples and good interaction between the silica particles and the PPO polymer in scenario of approach 2.

Application of ionic liquids in the mixed matrix membranes for CO2 separation: An overview

Membrane technology is highly promising in CO2 capture and separation process mainly because of its energy-efficiency and environmental friendliness. Mixed matrix membranes (MMMs) combine the excellent gas separation performance of fillers and the processability of polymer matrix, but it is still a challenge to enhance the gas separation performance for practical application. In this review, ionic liquids (ILs)-based MMMs with modified microstructures and improved separation performance are systematically introduced, which mainly due to the adjustability, the role of wetting agents, as well as the high CO2 affinity of ILs. The development of conventional ILs and functionalized ILs for CO2 separation are first briefly presented, following by the advance of ILs/fillers/polymers blended MMMs, ILs@fillers/polymers MMMs, ILs/fillers/PILs MMMs, and MMMs post-treated with ILs for CO2 separation. Meanwhile, the effects of ILs on the interfacial morphology, membranes microstructures and CO2 separation performance of membranes are emphasized. Finally, the understandings of challenges and perspectives of IL-based MMMs are proposed.

Constructing Mixed Matrix Membranes for Co2 Separation Based on Light Lanthanide Fluoride Nanosheets with Mesopores Structure

Constructing Mixed Matrix Membranes for Co2 Separation Based on Light Lanthanide Fluoride Nanosheets with Mesopores Structure

Constructing Mixed Matrix Membranes for Co2 Separation Based on Light Lanthanide Fluoride Nanosheets with Mesoporous Structure

Constructing Mixed Matrix Membranes for Co2 Separation Based on Light Lanthanide Fluoride Nanosheets with Mesoporous Structure

Cr-based MOF/IL composites as fillers in mixed matrix membranes for CO2 separation

New composite materials made of bromide-based ionic liquids (ILs) and metal–organic framework (MOF) MIL-101(Cr) were produced using two different ILs. The powdered composites [PMIM][Br]@MIL-101(Cr) and [BMIM][Br]@MIL-101(Cr) were rigorously characterized, and it was confirmed that both ILs were incorporated into the MOF structure. Single-component CO2 and N2 adsorption–desorption isotherms for the pristine MIL-101(Cr) and [BMIM][Br]@MIL-101(Cr), at 303 K and up to 10 bar, showed that the composite has lower gas adsorption capacity and selectivity when compared with the pristine MOF due to the IL incorporation. Mixed Matrix membranes (MMMs) were prepared by the solvent evaporation method, using Matrimid®5218 as the polymeric matrix, and MIL-101(Cr) and [email protected](Cr) composites as fillers with different loadings (10, 20 and 30 wt%). All prepared membranes were dense, except for the Matrimid®5218/[PMIM][Br]@MIL-101(Cr) ones, and their mechanical properties were improved by the presence of the IL in the composite fillers. Single-gas permeation experiments with CO2 and N2 were performed at 303 K for the Matrimid®5218/MIL-101(Cr) and Matrimid®5218/[BMIM][Br]@MIL-101(Cr) membranes, as the Matrimid®5218/[PMIM][Br]@MIL-101(Cr) showed voids. Independently of the filler percentage, the Matrimid®5218/MIL-101(Cr) membranes showed superior CO2 permeability than the Matrimid®5218/[BMIM][Br]@MIL-101(Cr) ones. In every case, the best CO2/N2 selectivity was achieved with a 20 wt% of filler loading, which indicates the existence of an optimum loading that yields the best membrane separation performance.

Recent Advances in Polymer-Inorganic Mixed Matrix Membranes for CO2 Separation.

Since the second industrial revolution, the use of fossil fuels has been powering the advance of human society. However, the surge in carbon dioxide (CO2) emissions has raised unsettling concerns about global warming and its consequences. Membrane separation technologies have emerged as one of the major carbon reduction approaches because they are less energy-intensive and more environmentally friendly compared to other separation techniques. Compared to pure polymeric membranes, mixed matrix membranes (MMMs) that encompass both a polymeric matrix and molecular sieving fillers have received tremendous attention, as they have the potential to combine the advantages of both polymers and molecular sieves, while cancelling out each other’s drawbacks. In this review, we will discuss recent advances in the development of MMMs for CO2 separation. We will discuss general mechanisms of CO2 separation in an MMM, and then compare the performances of MMMs that are based on zeolite, MOF, metal oxide nanoparticles and nanocarbons, with an emphasis on the materials’ preparation methods and their chemistries. As the field is advancing fast, we will particularly focus on examples from the last 5 years, in order to provide the most up-to-date overview in this area.

Development and Performance Evaluation of Cellulose Acetate-Bentonite Mixed Matrix Membranes for CO2 Separation

Membrane science is a state-of-the-art environmentally green technology that ascertains superior advantages over traditional counterparts for CO2 capture and separation. In this research, mixed matrix membranes (MMMs) comprising cellulose acetate (CA) with various loadings of bentonite (Bt) clay were fabricated by adopting the phase-inversion technique for CO2/CH4 and CO2/N2 separation. The developed pristine and MMMs were characterized for morphological, thermal, structural, and mechanical analyses. Several techniques such as scanning electron microscopy, thermogravimetric analysis, Fourier transformed infrared spectroscopy, and nano-indentation investigations revealed the promising effect of Bt clay in MMMs as compared to pristine CA membrane. Nano-indentation test identified that elastic modulus and hardness of the MMM with 1 wt. loading was increased by 64% and 200%, respectively, compared to the pristine membrane. The permeability decreased with the incorporation of Bt clay due to uniform dispersion of filler attributed to enhanced tortuosity for the gas molecules. Nevertheless, an increase in gas separation performance was observed with Bt addition up to 1 wt. loading. The opposite trend prevailed with increasing Bt concentration on the separation performance owing to filler agglomeration and voids creation. The maximum value of ideal selectivity (CO2/CH4) was achieved at 2 bar pressure with 1 wt. % Bt loading, which is 79% higher than the pristine CA membrane. For CO2/N2, the ideal selectivity was 123% higher compared to the pristine membrane with 1 wt. % Bt loading at 4 bar pressure.

MXene versus graphene oxide: Investigation on the effects of 2D nanosheets in mixed matrix membranes for CO2 separation

Two-dimensional titanium carbides, known as MXenes, have attracted growing attention in membrane research community. In this study, a typical MXene, Ti3C2Tx, is incorporated Pebax to fabricate mixed matrix membranes, for CO2 separation, with GO-filled membranes as reference. It is found that MXene-filled membranes afford much higher loading (up to 20 wt%) than GO-filled ones (up to 5 wt%) due to the rich polar groups at MXene surface and the resultant better interfacial interactions. More interestingly, dry-state membranes exhibit the optimal CO2 separation performance at quite low loading (at 1 wt%) for both GO and MXene, which is often seen in Pebax-based mixed matrix membranes, while the permeability and CO2/N2 selectivity of wet-state membranes proceed to increase when filler loading reaches 5 wt% or above, which represents an unusual comparison with the results collected under dry conditions. Since GO and MXene are used without any functionalization, such enhancement of CO2 separation performance at high loading under humidification can be only attributed to the hydrated interlayer channels of MXene/GO. These findings show the unique characteristics of 2D fillers, especially MXene, in wet-state mixed matrix membranes for CO2 separation, and also provide new information to better understand the roles of fillers in Pebax at different content or under different conditions.

A review and future prospect of polymer blend mixed matrix membrane for CO2 separation

In recent years, carbon capture technology has received much attention to limit the adverse effect caused by rising carbon dioxide (CO2) concentration in the atmosphere. Membrane technology has risen as an attractive option for carbon capture as it is less energy–intensive and more environmentally friendly compared with adsorption, absorption, and cryogenic separation. Polymeric membranes dominate the gas separation industries as they are cheaper and easier to fabricate compared with inorganic membranes but are bound to the permeance-selectivity trade-off limitation. Recently, researchers have been modifying polymeric membrane by polymer blending and mixed matrix membranes (MMMs) to overcome the limitation. Polymer blending yields a polymer blend that combines the benefits of two or more polymeric material. Polyethylene glycol (PEG) and polyethersulfone (PES) are common polymeric materials used in the gas separation industry for membrane fabrication. PEG and PES were reviewed in this paper as potential polymer blends that efficiently separate CO2 due to their chemical characteristics. Another technique to overcome the trade-off limitation is fabricating MMMs that incorporate both polymeric membrane material and inorganic filler. However, MMM fabrication presents challenges such as polymer-filler incompatibility, void formation, and filler agglomeration due to unsuitable filler. Functionalized multi-walled carbon nanotubes (MWCNTs-F) were reviewed as fillers that are able to overcome the dispersion and polymer-compatibility issues and increase the gas separation performance of membranes. Hence, MMM that is fabricated from PEG, PES, and MWCNTs-F that combines both polymer blending and MMM techniques is believed to be a breakthrough for CO2/N2 separation.

Comparison between ZIF-67 and ZIF-8 in Pebax® MH-1657 mixed matrix membranes for CO2 separation

In this study, mixed matrix membranes (MMM) based on poly(ether-b-amide) or Pebax® were prepared using a synthetized ZIF-67 and a commercial ZIF-8 (Basolite® Z1200) to determine the effect of particle content (0, 2, 3, 4 and 5 wt%) on CO2, CH4 and N2 single gas permeability as well as CO2/CH4 and CO2/N2 ideal selectivity. The MMM morphology was evaluated first by scanning electron microscopy (SEM) where excellent dispersion without aggregation was observed. The thermal properties were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showing the disruptive role of fillers on polymer chain mobility. Fourier transform infrared spectroscopy (FTIR) showed that no significant chemical interaction between the polymer and ZIF particles occurred. Finally, gas permeation results at 35 °C and 11 bar revealed higher CO2 permeability for all MMM, but especially for Pebax/ZIF-67 with a 130% increase (162 Barrer) compared to the pristine Pebax membrane (70 Barrer), while the Pebax/ZIF-8 produced a lower (85%) increase (130 Barrer). Due to the smaller pore aperture of ZIF-67, CO2 selectivity over CH4 and N2 was higher compared to ZIF-8. Overall, the Pebax/ZIF-67 system was able to overcome the Robeson upper bound for the CO2/N2 separation.

Effect of PEG-MEA and graphene oxide additives on the performance of Pebax®1657 mixed matrix membranes for CO2 separation

In this work, a series of mixed matrix membranes (MMMs) consisting of Pebax® 1657 as the main polymer matrix, poly(ethylene glycol) (PEG) derivatives with low molecular weights as additives, and graphene oxide (GO) with different loadings as a nanofiller, were prepared for CO2/N2 separation. Changes in the amorphous and crystalline regions of Pebax®/PEG blend membranes and in the free volume of GO-embedded MMMs were estimated based on differential scanning calorimetry (DSC) thermograms. The fractional free volume and density of the Pebax®/PEG blend membranes were investigated according to additive models. Particularly, blending poly(ethylene glycol) methyl ethyl acrylate (PEG-MEA) with the Pebax® matrix significantly improved CO2 permeability without sacrificing high CO2/N2 selectivity. Incorporating GO nanosheets up to 0.3 wt% into the Pebax®/PEG-MEA matrix was found to have a considerable impact on increasing CO2/N2 selectivity, due to largely in part to an increase in the CO2 solubility coefficients. Upon a further increase in GO loading, both CO2 permeability and CO2/N2 selectivity decreased as a result of increasing tortuosity for gas diffusion and also GO aggregation at high GO loading content. More importantly, the Pebax®/PEG-MEA blend membrane with the optimized loading of GO, i.e., 0.3 wt% indicated outstanding anti-CO2 plasticization resistance up to 10 bar as well as long-term stability over 100 days without significant deterioration of CO2/N2 separation performance.

Facilitated transport graphene oxide based PPOdm mixed matrix membrane for CO2 separation

In this work, a novel class of Mixed Matrix Membrane (MMM) has been prepared by incorporating graphene oxide (GO) at different loading in glassy poly (2,6-dimethyl-1,4-phenylene oxide) (PPOdm) polymer matrix via dry-phase inversion technique. The resultant MMM was characterized and the effect of embedded GO nanosheets on the performance of the MMM was investigated using pure CO2 and CH4 gases. MMM at 5 wt% GO loading displays the optimum gas separation performance with an ideal CO2/CH4 selectivity and CO2 permeability values of 40.27 and 80.95 barrer, respectively. Compared to pristine PPOdm membrane, the CO2/CH4 ideal selectivity and CO2 permeability values increased by 781% and 15%, respectively. The high-aspect ratio of GO with surface hydroxyl and carboxyl groups facilitates the transport mechanism of CO2 molecules, acted as a selective barrier and eventually renders high selectivity value

Ionic cross-linked polyether and silica gel mixed matrix membranes for CO2 separation from flue gas

Abstract Mixed matrix membranes (MMMs) were prepared by incorporating 10 wt%, 20 wt% and 30 wt% silica gel filler particles into novel ionic cross-linked polyether (IXPE) polymers. Porous silica gel has the advantage of high surface area that can increase the free volume and permeability in a polymer film while also being commercially available and low cost. The MMMs featured high chemical and thermal stability as well as a modest improvement in storage modulus. These features are due to the excellent interfacial interaction between silica gel filler particles and the polymer matrix. Increasing the loading of silica gel particles in MMMs resulted in higher permeability up to 120 Barrer for CO 2 , which is about 40% higher than the neat polymer matrix. Most importantly, the MMMs maintained a very high CO 2 /N 2 selectivity performance of around 41 for all particle loadings that were tested.

Recent advances on mixed matrix membranes for CO2 separation

Recent advances on mixed matrix membrane for CO2 separation are reviewed in this paper. To improve CO2 separation performance of polymer membranes, mixed matrix membranes (MMMs) are developed. The concept of MMM is illustrated distinctly. Suitable polymer and inorganic or organic fillers for MMMs are summarized. Possible interface morphologies between polymer and filler, and the effect of interface morphologies on gas transport properties of MMMs are summarized. The methods to improve compatibility between polymer and filler are introduced. There are eight methods including silane coupling, Grignard treatment, incorporation of additive, grafting, in situ polymerization, polydopamine coating, particle fusion approach and polymer functionalization. To achieve higher productivity for industrial application, mixed matrix composite membranes are developed. The recent development on hollow fiber and flat mixed matrix composite membrane is reviewed in detail. Last, the future trend of MMM is forecasted.

Thermally rearranged mixed matrix membranes for CO2 separation: An aging study

In this work, the aging behavior of a thermally rearranged polybenzoxazole-co-imide (TR-PBOI) mixed matrix membrane loaded with 0.5wt.% of oxidized multi-wall carbon nanotubes (MWCNT) was evaluated and then compared to a pure TR polymeric membrane prepared from the same precursor. To the best of authors knowledge, this is the first report of a mixed matrix membrane being prepared through the dispersion of MWCNTs within a thermally rearranged polymer matrix for CO2 separation. Microporous structures were created in both membranes when thermally rearranged at 375°C, facilitating fast mass transfer ideal for membrane gas separation. The TR mixed matrix membrane with oxidized CNTs demonstrated improved separation properties with regard to both permeability and selectivity compared to the pure TR polymeric membrane due to a greater degree of thermal rearrangement (11.3%) than what was exhibited by the TR membrane (6.7%). Moreover, the high CO2 solubility typical of TR polymers coupled with diffusivity enhancements improved the CO2/N2 selectivity. The addition of oxidized CNTs to the TR-PBOI polymer did not significantly influence the aging behavior of the mixed matrix membrane. Both pure TR-PBOI and mixed matrix membranes exhibited an increase in CO2 selectivity due to physical aging. The improved separation properties in conjunction with an unchanged membrane stability over time suggested that the addition of CNTs to pure TR membranes could be an excellent approach toward improving the performance of thermally rearranged membranes applied toward gas separation.

MIL-125(Ti) based mixed matrix membranes for CO2 separation from CH4 and N2

Mixed matrix membranes (MMMs) were developed by adding MIL-125(Ti) and the amine-functionalized counterpart as fillers to Matrimid® polyimide. Through a well-optimized synthesis, strong performing MMMs with loadings up to 30wt% could be prepared. SEM images of the synthesized MMMs confirmed the good adhesion to and dispersion of the fillers within the polymer matrix. Significantly improved CO2 mixed gas selectivities and permeabilities for (50:50) CO2:N2 and CO2:CH4 gas mixtures at 9bar and 308K were achieved. The separation results demonstrated that the overall separation efficiency is increased by the addition of both MIL-125 and NH2-MIL-125 fillers but that the NH2-functionalized filler is preferred as it leads to higher selectivities and permeabilities. The performance of the membranes was compared to previously reported literature data for (CO2:CH4) separation which shows that carefully tuned membrane synthesis procedure along with right selection of polymer and filler are crucial factors to get a highly selective and permeable membrane. Among non-fluorinated polymers forming the membrane matrix, present data outperform all previously reported MMM separation. MMMs based on fluorinated polyimide showed slightly higher selectivities, but much lower permeabilities.