264 research outputs found
Permeation of Several Gases through Elastomers, with Emphasis on the Deuterium/hydrogen Pair
The Diffusion and Permeation Coefficients for He, H2, D2, O2, and N2 in a Variety of Elastomers Were Measured by Simple Manometric Methods. the Elastomers Studied Were Butyl Rubber; HypalonÂź 40 and 45; VitonÂź E60 and GF; HydrinÂź 100 and Filled HydrinÂź 100; KratonÂź G, FG, and KG VTEOS; EPDM; Epoxidized Natural Rubber; and Neoprene. Consistent with Earlier Studies, Elastomers with Higher Glass Transition Temperatures Exhibited Lower Diffusion Coefficients. the Ratio of Diffusion Coefficients of the Hydrogen Isotope Pair Differed from the Purely Molecularâweightâbased Prediction. Deuterium\u27s Slightly Smaller Size Relative to Hydrogen is Consistent with Observed Deviations from the Molecularâweightâbased Diffusion Coefficient Ratio. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc
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Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications. Final report
During the three years of support under this grant, ten novel polymer structures have been synthesized and characterized in detail in terms of sorption and transport properties to test the hypotheses on strategies to develop advanced materials for gas separation membranes. The extremely important O{sub 2}/N{sub 2} and CO{sub 2}/CH{sub 4} systems have been the focus of this work. Data for permeabilities and permselectivities for O{sub 2}/N{sub 2} and CO{sub 2}/CH{sub 4} at 35 C at approximately 2 atm feed pressure for O{sub 2} and N{sub 2} and 10 atm for CO{sub 2} and CH{sub 4} are reported in two tables and will be discussed in two parts, one related to each of the groups of structures in these two tables. For the sake of efficiency, the author will only consider the O{sub 2}/N{sub 2} data; however, similar trends apply for the CO{sub 2}/CH{sub 4} system as well. This gas pair is useful, since solubility selectivity effects are generally of much smaller importance than for the CO{sub 2}/CH{sub 4} pair, so even without detailed solubility and diffusivity data, mobility selectivity based arguments tend to be adequate
Polyimide hollow fiber membranes for CO2 separation from wet gas mixtures
MatrimidÂź5218 hollow fiber membranes were prepared using the dry-wet spinning process. The transport properties were measured with pure gases (H2, CO2, N2, CH4 and O2) and with a mixture (30% CO2 and 70% N2) in dry and wet conditions at 25 ÂșC, 50 ÂșC, 60 ÂșC and 75 ÂșC and up to 600 kPa. Interesting values of single gas selectivity up to 60 ÂșC (between 31 and 28 for CO2/N2 and between 33 and 30 for CO2/CH4) in dry condition were obtained. The separation factor measured for the mixture was 20% lower compared to the single gas selectivity, in the whole temperature range analyzed. In saturation conditions the data showed that water influences the performance of the membranes, inducing a reduction of the permeance of all gases. Moreover, the presence of water caused a decrease of single gas selectivity and separation factor, although not so significant, highlighting the very high water resistance of hollow fiber membrane modules
Purification of Propylene and Ethylene by a Robust MetalâOrganic Framework Mediated by HostâGuest Interactions
From Wiley via Jisc Publications RouterHistory: received 2021-03-19, pub-electronic 2021-06-07Article version: VoRPublication status: PublishedFunder: Engineering and Physical Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/I011870, EP/R00661X/1, EP/S019367/1, EP/P025021/1, EP/P025498/1Funder: European Research Council; Id: http://dx.doi.org/10.13039/501100000781; Grant(s): 742401Abstract: Industrial purification of propylene and ethylene requires cryogenic distillation and selective hydrogenation over palladium catalysts to remove propane, ethane and/or trace amounts of acetylene. Here, we report the excellent separation of equimolar mixtures of propylene/propane and ethylene/ethane, and of a 1/100 mixture of acetylene/ethylene by a highly robust microporous material, MFMâ520, under dynamic conditions. In situ synchrotron single crystal Xâray diffraction, inelastic neutron scattering and analysis of adsorption thermodynamic parameters reveal that a series of synergistic hostâguest interactions involving hydrogen bonding and Ïâ
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Ï stacking interactions underpin the cooperative binding of alkenes within the pore. Notably, the optimal pore geometry of the material enables selective accommodation of acetylene. The practical potential of this porous material has been demonstrated by fabricating mixedâmatrix membranes comprising MFMâ520, Matrimid and PIMâ1, and these exhibit not only a high permeability for propylene (â1984 Barrer), but also a separation factor of 7.8 for an equimolar mixture of propylene/propane at 298 K
Hybrid Polyhedral Oligomeric SilsesquioxanesâImides with Tailored Intercage Spacing for Sieving of Hot Gases
Preparation, characterization and gas permeation study of PSf/MgO nanocomposite membrane
Potential link between MHCâself-peptide presentation and hematopoiesis; the analysis of HLA-DR expression in CD34-positive cells and self-peptide presentation repertoires of MHC molecules associated with paroxysmal nocturnal hemoglobinuria
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Synthesis and analysis of novel polymers with high permselectivity and permeability in gas separation applications
Significant progress was made toward developing advanced materials for gas separation membrane applications and rationalizing molecular structure and efficacy: Synthesized and tested polyarylates based on terephthalic or isophthalic acid or a tertiary butyl derivative of the isophthalic acid with different diols to illustrate the effects of: opening'' the matrix by incorporation of bulky packing inhibiting groups such as the tertiary butyl moiety inhibition of backbone motion via meta connected backbone connections and tightening'' of the matrix by incorporation of polar halogens. Completed high temperature characterization of sorption and transport properties for novel materials. Continued studies of the phenyl-substituted polymers aimed at producing super stable high temperature useful polymers for gas separations. Synthesized a polyarylate based on the spirobiindane diol and bibenzoyl acid chloride to incorporate long flat packable bibenzoyl units between packing disruptive spirobiindane units in an attempt to control the segmental level morphology to produce highly selective bottleneck'' regions between highly open regions
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