Membranes composed of Polymers of Intrinsic Microporosity (PIMs) have the potential for energy efficient industrial gas separations. Here we report the synthesis and gas permeability data of a series ...of ultrapermeable PIMs, of two-dimensional chain conformation and based on benzotriptycene structural units, that demonstrate remarkable ideal selectivity for most gas pairs of importance. In particular, the CO2 ultrapermeability and high selectivity for CO2 over CH4, of key importance for the upgrading of natural gas and biogas, and for CO2 over N2, of importance for cost-effective carbon capture from power plants, exceed the performance of the current state-of-the-art polymers. All of the gas permeability data from this series of benzotriptycene-based PIMs are placed well above the current 2008 Robeson upper bounds for CO2/CH4 and CO2/N2. Indeed, the data for some of these polymers fall into a linear correlation on the benchmark Robeson plots i.e. log(PCO2/PCH4) versus log PCO2 and log(PCO2/PN2) versus log PCO2, which are parallel to, but significantly above, that of the 2008 CO2/CH4 and CO2/N2 upper bounds, allowing their revision. The redefinition of these upper bounds sets new aspirational targets for polymer chemists to aim for and will result in more attractive parametric estimates of energy and cost efficiencies for carbon capture and natural/bio gas upgrading using state-of-the-art CO2 separation membranes.
Two-dimensional (2D) materials are receiving increasing attention in the field of gas separation as they promise to deliver the step change in performance that has been sought for decades. Research ...has focussed on the exploration of novel 2D structures, improvement in their fabrication technique and understanding their unique features. Their exploitation is still hindered by more limited efforts in terms of scale up, not only of the 2D building blocks but also of membrane productions, and in the investigation of the stability under real conditions. The recent reports on scaling-up attempt are summarised in this review. A joint effort between academia and manufacturer seems now crucial to unlock the potential of this technology.
The current concentration of carbon dioxide in the atmosphere demands for development of negative emission solutions such as direct carbon dioxide removal from the atmosphere (air capture). Many ...well-established processes can remove carbon dioxide from the atmosphere but the real technological challenge consists of concentrating and compressing carbon dioxide at the conditions for long term geological storage, with efficient use of non-fossil energy sources. A thermally-driven, negative-carbon adsorption process for capture, purification and compression of carbon dioxide from air is proposed. The process is based on a series of batch adsorption compressors of decreasing size to deliver a compressed carbon dioxide stream to a final storage. Thermodynamic analysis of the process shows that, by exploiting the equilibrium properties of commercial and non-commercial materials, carbon dioxide can be produced at specifications appropriate for geological storage. By operating the process with zeolite 13X at regeneration temperature of 95 °C, a final storage vessel can be pressurized with carbon dioxide at purities >0.95 mol fraction and specific energy consumption <2.2 MJth molCO2−1. Tailored materials provide a step-change in performance. When the process operates with zeolite NaETS-4, carbon dioxide can be purified at values >0.97 mol fraction.
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•A simple heat-powered carbon-negative process is analysed for air capture.•The process can remove, compress and purify carbon dioxide by using low grade heat.•The process meets the specifications required to direct air capture.
Mixed matrix membranes (MMMs) combine the high separation performance of porous materials with the processibility of polymers and so possess potential for carbon capture from CO2-containing gas ...streams. Zeolitic imidazolate frameworks (ZIFs) are promising candidates as molecular-sieve fillers in MMMs due to their tunability and ease of synthesis. We have compared four ZIFs, all as nanoparticles of similar sizes (ca. 400 nm), as MMM fillers, to investigate the effects of ZIF structure and chemistry on MMM performance of pure gas (CO2, N2) permeation under the same conditions. The chosen ZIFs include two that exhibit strong CO2 adsorption (hybrid ZIF-7/COK-17 and ZIF-94) and two that have higher pore volumes but weaker CO2 interactions (ZIF-8 and a hybrid ZIF-11/ZIF-71). The hybrid ZIF-7/COK-17 and ZIF-94 are structurally related to ZIF-7 (rhombohedral sod topology) and ZIF-8 (cubic sod), respectively, via partial or complete substitution of benzimidazole or 2-methylimidazole by 4,5-dichloroimidazole or 4-methyl-5-imidazolecarboxaldehyde, while the hybrid ZIF-11/ZIF-71 has the rho topology but the same composition as the ZIF-7/COK-17 hybrid. In the first part of the comparative study, MMMs based on two types of commercial polymers, Matrimid®5218 and PEBAX-MH1657, were prepared containing the ZIF-7/COK-17 hybrid and also with ZIF-94. ZIF-94 shows much better compatibility with the polymers, forming homogeneous dispersions at all loadings attempted (≤35 % wt%) whereas the hybrid shows inhomogeneity above 12 wt% in each case. At 12 wt% loading, both fillers show an increase in CO2 permeability at 1.2 bar and 293 K compared to the pure membrane (in PEBAX, this increases from 49.5 to 60 and 68 Barrer) which is the result of increased solubility compensating for decreased diffusivity, and this improvement in permeability continues to increase at the higher levels of loading possible with ZIF-94. ZIF-7/COK-17 in PEBAX show higher selectivity, achieving a calculated CO2/N2 selectivity up to 70. Further investigation of CO2 and N2 permeation on MMMs with the four ZIFs at 12 wt% in PEBAX-MH1657 showed a clear distinction between the ZIF-94 and ZIF-7/COK-17 MMMs (which show higher membrane solubilities but lower diffusivities) compared to ZIF-8 and ZIF-11/ZIF-71 MMMs. At the loading chosen, the CO2 permeability increase achieved by the four ZIFs over PEBAX-MH1657 increases in the order ZIF-11/-71, ZIF-7-COK-17 (ca. 60 Barrer) < ZIF-94 (68) < ZIF-8 (81), reflecting the complex interplay between CO2 solubility (increasing with interaction strength) and diffusivity (increasing with available cage and window size). The calculated CO2/N2 selectivity is highest for the hybrid ZIF-7/COK-17 membrane (70), which is attributed to molecular sieving effects in the rhombohedral sod structure
Action Observation Training (AOT) promotes the acquisition of motor abilities. However, while the cortical modulations associated with the AOT efficacy are well known, few studies investigated the ...AOT peripheral neural correlates and whether their dynamics move towards the observed model during the training. We administered seventy-two participants (randomized into AOT and Control groups) with training for learning to grasp marbles with chopsticks. Execution practice was preceded by an observation session, in which AOT participants observed an expert performing the task, whereas controls observed landscape videos. Behavioral indices were measured, and three hand muscles' electromyographic (EMG) activity was recorded and compared with the expert. Behaviorally, both groups improved during the training, with AOT outperforming controls. The EMG trainee-model similarity also increased during the training, but only for the AOT group. When combining behavioral and EMG similarity findings, no global relationship emerged; however, behavioral improvements were "locally" predicted by the similarity gain in muscles and action phases more related to the specific motor act. These findings reveal that AOT plays a magnetic role in motor learning, attracting the trainee's motor pattern toward the observed model and paving the way for developing online monitoring tools and neurofeedback protocols.
Membranes composed of Polymers of Intrinsic Microporosity (SBF-PIMs) have potential for commercial gas separation. Here we report a combined simulation and experimental study to investigate the ...effect on polymer microporosity and gas permeability by placing simple substituents such as methyl, t -butyl and fused benzo groups onto PIMs derived from spirobifluorene (PIM-SBFs). It is shown that methyl or t -butyl substituents both cause a large increase in gas permeabilities with four methyl groups enhancing the concentration of ultramicropores (<0.7 nm), which contribute to selective gas transport. The t -butyl substituents lower selectivity by generating a greater concentration of larger, less selective, micropores (>1.0 nm). Long-term ageing studies (>3.5 years) demonstrate the potential of PIM-SBFs as high-performance membrane materials for gas separations. In particular, the data for the PIM derived from tetramethyl substituted SBF reaches the proposed 2015 Robeson upper bound for O 2 /N 2 and, hence, hold promise for the oxygen or nitrogen enrichment of air. Mixed gas permeation measurements for CO 2 /CH 4 of the aged PIM-SBFs also demonstrate their potential for natural gas or biogas upgrading.
A novel polymer of intrinsic microporosity (PIM) was prepared from a diaminobenzotriptycene monomer using a polymerization reaction based on Tröger’s base formation. The polymer (PIM-BTrip-TB) ...demonstrated an apparent Brunauer, Emmet, and Teller (BET) surface area of 870 m2 g–1, good solubility in chloroform, excellent molecular mass, high inherent viscosity and provided robust thin films for gas permeability measurements. The polymer is highly permeable (e.g., PH2 = 9980; PO2 = 3290 Barrer) with moderate selectivity (e.g., PH2/PN2 = 11.0; PO2/PN2 = 3.6) so that its data lie over the 2008 Robeson upper bounds for the H2/N2, O2/N2, and H2/CH4 gas pairs and on the upper bound for CO2/CH4. On aging, the polymer demonstrates a drop in permeability, which is typical for ultrapermeable polymers, but with a significant increase in gas selectivities (e.g., PO2 = 1170 Barrer; PO2/PN2 = 5.4).
This study reports the preparation of waterproof/breathable films based on amidoxime functionalized PIM-1, which were processed into fibrous membrane using the electrospinning process with a green ...solvent, i.e. dimethyl sulfoxide. The influence of the feed solution (polymer concentration, solvent nature, presence of salt) and the electrospinning process conditions (flow rate, distance between the tip and the collector and voltage) has been investigated in order to obtain bead-free, thin fibres with regular structure and low porosity. The addition of salt allowed the production of nanofibres at low polymer concentration, resulting in the fabrication of fibrous mats with 1.5 μm diameter fibres and porosity below 10 μm. These fibre mats possess a hydrophobic character with a contact angle superior to 90°. Moreover, they are breathable, but not permeable to liquid water, which is essential for use within protective gear (i.e. gas masks or protective clothing).
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•Fabrication of bead-free AOPIM-1 fibres by electrospinning with a green solvent, DMSO.•Production of fibrous mats with 1.5 μm diameter and pore size below 10 μm.•Demonstration of a hydrophobic character with a water contact angle superior to 90°.•Demonstration of a good air breathability and waterproof character.
Carbon capture and storage update Boot-Handford, Matthew E; Abanades, Juan C; Anthony, Edward J ...
Energy & environmental science,
01/2014, Letnik:
7, Številka:
1
Journal Article
Recenzirano
In recent years, Carbon Capture and Storage (Sequestration) (CCS) has been proposed as a potential method to allow the continued use of fossil-fuelled power stations whilst preventing emissions of CO
...2
from reaching the atmosphere. Gas, coal (and biomass)-fired power stations can respond to changes in demand more readily than many other sources of electricity production, hence the importance of retaining them as an option in the energy mix. Here, we review the leading CO
2
capture technologies, available in the short and long term, and their technological maturity, before discussing CO
2
transport and storage. Current pilot plants and demonstrations are highlighted, as is the importance of optimising the CCS system as a whole. Other topics briefly discussed include the viability of both the capture of CO
2
from the air and CO
2
reutilisation as climate change mitigation strategies. Finally, we discuss the economic and legal aspects of CCS.
A comprehensive discussion of CCS technologies, deployment and prospects across the world.
Carbon dioxide capture from cement plant flue gas can play an important role in mitigating CO2 emission that lead to climate change. Among all the technologies evaluated, membranes have potential to ...be one of the most energy-efficient and low-cost CO2 capture option. In this work, a novel membrane technology, Facilitated Transport Membranes (FTMs), is assessed to further reduce energy demand and cost for CO2 capture in a cement plant. A new process that employs FTMs is simulated and applied to a real clinker production plant in Italy (Colacem, Gubbio). The process is then compared with other carbon capture technologies. Results show that the FTM technology can be competitive with other technologies despite the need of steam to operate the membrane. Despite the benefit in terms of specific emission compared to more established absorption with liquid amines process, further improvements on membrane performances are needed to gain also an economic advantage for carbon capture in the cement industry.
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