Surface-modified polysulfone membranes: aqueous phase oxidation via persulfate radical

Peer reviewed: YesNRC publication: Ye

Separation performance of asymmetric membranes based on PEGDa/PEI semi interpenetrating polymer network in pure and binary gas mixtures of CO2, N2 and CH4

Asymmetric membranes of semi-interpenetrating polymer networks (semi-IPN) were prepared with commercial poly (ether imide) (ULTEM\uae) and poly (ethylene glycol) diacrylate (PEGDa) in 1-methyl-2-pyrrolidinone (NMP). The selectivity and permeance of pure and mixed gases using carbon dioxide (CO2) feed concentrations of 10\u201340% in nitrogen (N2) or methane (CH4) were measured by the constant pressure and variable volume method at an absolute feed pressure of 1.35MPa and 22 \u25e6C. The pure gas selectivity matched the mixed gas selectivity values at different feed concentrations, which indicated absence of plasticization. The fugacity based CO2/N2 selectivity of a semi-IPN with 6% PEGDa solids content reached 50\ub14, which is comparable to the pure gas selectivity of a dense PEGDa film (alpha = 54) and is significantly higher than the dense film selectivity of PEI (alpha = 28). The selectivity for CO2/CH4 mixtures is 43\ub110,comparable to the dense film properties of PEI (alpha = 39) and not the dense film selectivity of PEGDa (alpha = 20). The PEGDa/PEI semi-IPN membranes displayed synergistic properties, where the selectivity approached the higher value of the two materials used in making the semi-IPNs.Peer reviewed: YesNRC publication: Ye

Synthesis and characterization of bis (4-maleimidophenyl) fluorene and its semi interpenetrating network membranes with polyther imide (Ultem 1000)

A semi-interpenetrating network (semi-IPN) of bis (4-maleimidophenyl) fluorene (cardo-BMI) and polyether imide (PEI, Ultem\uae 1000) was prepared. The structure of bis (4-maleimidophenyl) fluorene and the corresponding semi-IPNs was determined by nuclear magnetic resonance and Fourier transform infrared spectroscopy, respectively. The thermal properties of the cardo-BMI and semi-IPNs were evaluated by thermogravimetry and differential scanning calorimetry. The semi-IPNs exhibited thermal stability up to 480 \ub0C. The morphology of the semi-IPNs was evaluated by scanning electron microscopy. Asymmetric membranes were prepared from the semi-IPN material by the wet phase inversion method. The pure gas permeation properties of the PEI and semi-IPN membranes were evaluated for oxygen (O2), nitrogen (N2), carbon dioxide (CO2) and methane (CH4) by the constant pressure and variable volume method at an absolute feed pressure of 0.69 MPa at 22 \ub0C. The CO2/N2 selectivity of 39.2 \ub1 3.0 with a CO2 permeance of 18.3 \ub1 4.0 GPU of semi-IPN membrane was higher than the PEI membranes (selectivity 21.6 \ub1 4.1 and CO2 permeance 0.5 \ub1 0.1 GPU). The highest CO2/CH4 selectivity of the semi-IPN membrane was 49.3 \ub1 3.5 compared to 37 for a PEI dense film. Among the semi-IPN membranes, those with 5 wt% cardo-BMI exhibited better performance than the 1% and 10%.Peer reviewed: YesNRC publication: Ye

Polysulfone membranes. V. Poly(phenyl sulfone) (Radel R)-poly(vinyl pyrrolidone) membranes

Peer reviewed: YesNRC publication: Ye

Simulation of membrane-based CO2 capture in a coal-fired power plant

A two-stage membrane process is designed for CO2 capture from coal-fired power plants. Vacuum operation on the permeate side of the membrane is the preferred option to reduce the power demand for compressing the huge feed volume. The energy recovered from the CO2-depleted emission stream and the energy consumed for post-capture CO2 liquefaction are considered in this simulation study. A numerical modeling of the membrane process and a brief description on assessing both the capital and operating costs of the process are provided. It is found that the membrane area requirement is dominated by recovery of the lower concentrations of CO2 in the tail portion of the flue gas stream. Process optimizations allowing the minimal CO2 capture cost or minimal power demand indicate that current membrane technology is promising for flue gas CO2 capture, assuming a permeance of 1000 GPU and CO2/N2 selectivity of 30. The potential of membrane technology for CO2 capture was also explored by using membranes with a CO2/N2 selectivity of 50 and 200.Peer reviewed: YesNRC publication: Ye

Decarboxylation-induced cross-linking of polymers of intrinsic microporosity (PIMs) for membrane gas separation

Peer reviewed: YesNRC publication: Ye

Advances in high permeability polymeric membrane materials for CO2 separations

Global CO2 emissions have increased steadily in tandem with the use of fossil fuels. A paradigm shift is needed in developing new ways by which energy is supplied and utilized, together with the mitigation of climate change through CO2 reduction technologies. There is an almost universal acceptance of the link between rising anthropogenic CO2 levels due to fossil fuel combustion and global warming accompanied by unpredictable climate change. Therefore, renewable energy, non-fossil fuels and CO2 capture and storage (CCS) must be deployed on a massive scale. CCS technologies provide a means for reducing greenhouse gas emissions, in addition to the current strategies of improving energy efficiency. Coal-fired power plants are among the main large-scale CO2 emitters, and capture of the CO2 emissions can be achieved with conventional technologies such as amine absorption. However, this energy-consuming process, calculated at approximately 30 percent of the power plant capacity, would result in unacceptable increases in power generation costs. Membrane processes offer a potentially viable energy-saving alternative for CO2 capture because they do not involve any phase transformation. However, typical gas separation membranes that are currently available have insufficiently high permeability to be able to process the massive volumes of flue gas, which would result in a high CO2 capture. Polymer membranes highly permeable to CO2 and having good selectivity should be developed for the membrane process to be viable. This perspective review summarizes recent noteworthy advances in polymeric materials having very high CO2 permeability and good CO2/N2 selectivity that largely surpass the separation performance of conventional polymer materials. Five important classes of polymer membrane materials are highlighted: polyimides, thermally rearranged polymers (TRs), substituted polyacetylenes, polymers with intrinsic microporosity (PIM) and polyethers, which provide insights into polymer designs suitable for CO2 separation from, for example, the post-combustion flue gases in coal-fired power plants.Peer reviewed: YesNRC publication: Ye

Polymers of intrinsic microporosity (PIMs) substituted with methyl tetrazole

A polymer of intrinsic microporosity (PIM-1) containing nitrile groups was reacted by [2 + 3] cycloaddition reaction to give a polymer substituted with tetrazole groups (TZ-PIM), and then was further methylated to give a new PIM substituted with methyl tetrazole groups (MTZ-PIM). In contrast to TZ-PIMs, the MTZ-PIMs had distinctly improved solubility characteristics, enabling a more detailed investigation of the degree of conversion for the cycloaddition reaction and the structures of TZ-PIMs, which showed the presence of two kinds of tetrazole rings. Compared with PIM-1, the MTZ-PIM showed higher gas permselectivity with a corresponding decrease in gas permeability for pure gas pairs such as O\u2082/N\u2082 and CO\u2082/N\u2082, and for mixed gases, such as CO\u2082/N\u2082. Data for selectivity coupled with high gas permeability is close to the Robeson 2008 upper-bound performance limit for the O\u2082/N\u2082 and CO2/N2 pure gas pairs, and exceeds the upper-bound for the CO\u2082/N\u2082 mixed gas pair.Peer reviewed: YesNRC publication: Ye

Azide-based Cross-Linking of Polymers of Intrinsic Microporosity (PIMs) for Condensable Gas Separation

Peer reviewed: YesNRC publication: Ye

Gas Transport in a Polymer of Intrinsic Microporosity (PIM-1) Substituted with Pseudo-Ionic Liquid Tetrazole-Type Structures

We report a side group modification strategy to tailor the structure of a polymer of intrinsic microporosity (PIM-1). PIM-1 with an average of ∼50% of the repeat units converted to tetrazole is prepared, and a subsequent reaction then introduces three types of pseudo-ionic liquid tetrazole-like structures (PIM-1-ILx). The presence of pseudo-ionic liquid functional groups in the PIM-1 structure increases gas selectivities for O2/N2 and CO2/N2, while it decreases pure-gas permeabilities. The overall gas separation performance of PIM-1-ILx is close to the 2008 Robeson upper bound. Since the tetrazoles are versatile groups for building a wide variety of ionic liquids, the modification method can be expanded to explore a broad spectrum of functional groups