scholarly journals Zeolite-like performance for xylene isomer purification using polymer-derived carbon membranes

2021 ◽  
Vol 118 (37) ◽  
pp. e2022202118
Author(s):  
Yao Ma ◽  
Nicholas C. Bruno ◽  
Fengyi Zhang ◽  
M. G. Finn ◽  
Ryan P. Lively
Keyword(s):  
Ring Structure ◽  
Polymer Backbone ◽  
Carbon Membranes ◽  
Repeat Units ◽  
Current State ◽  
Polymer Of Intrinsic Microporosity ◽  
Two Factors ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity ◽  
Xylene Isomer

Polymers of intrinsic microporosity (PIMs) have been used as precursors for the fabrication of porous carbon molecular sieve (CMS) membranes. PIM-1, a prototypical PIM material, uses a fused-ring structure to increase chain rigidity between spirobisindane repeat units. These two factors inhibit effective chain packing, thus resulting in high free volume within the membrane. However, a decrease of pore size and porosity was observed after pyrolytic conversion of PIM-1 to CMS membranes, attributed to the destruction of the spirocenter, which results in the “flattening” of the polymer backbone and graphite-like stacking of carbonaceous strands. Here, a spirobifluorene-based polymer of intrinsic microporosity (PIM-SBF) was synthesized and used to fabricate CMS membranes that showed significant increases in p-xylene permeability (approximately four times), with little loss in p-xylene/o-xylene selectivity (13.4 versus 14.7) for equimolar xylene vapor separations when compared to PIM-1–derived CMS membranes. This work suggests that it is feasible to fabricate such highly microporous CMS membranes with performances that exceed current state-of-the-art zeolites at high xylene loadings.

scholarly journals The immobilisation and reactivity of Fe(CN)63−/4− in an intrinsically microporous polyamine (PIM-EA-TB)

2020 ◽  
Vol 24 (11-12) ◽  
pp. 2797-2806 ◽  
Author(s):  
Lina Wang ◽  
Richard Malpass-Evans ◽  
Mariolino Carta ◽  
Neil B. McKeown ◽  
Frank Marken
Keyword(s):  
Carbon Electrodes ◽  
Microporous Structure ◽  
Polymer Backbone ◽  
Glassy Carbon Electrodes ◽  
Rigid Polymer ◽  
Redox Active ◽  
Microporous Polymer ◽  
Polymer Of Intrinsic Microporosity ◽  
Ph Dependent ◽  
Intrinsic Microporosity

Abstract Protonation of the molecularly rigid polymer of intrinsic microporosity PIM-EA-TB can be coupled to immobilisation of Fe(CN)63−/4− (as well as immobilisation of Prussian blue) into 1–2 nm diameter channels. The resulting films provide redox-active coatings on glassy carbon electrodes. Uptake, transport, and retention of Fe(CN)63−/4− in the microporous polymer are strongly pH dependent requiring protonation of the PIM-EA-TB (pKA ≈ 4). Both Fe(CN)64− and Fe(CN)63− can be immobilised, but Fe(CN)64− appears to bind tighter to the polymer backbone presumably via bridging protons. Loss of Fe(CN)63−/4− by leaching into the aqueous solution phase becomes significant only at pH > 9 and is likely to be associated with hydroxide anions directly entering the microporous structure to combine with protons. This and the interaction of Fe(CN)63−/4− and protons within the molecularly rigid PIM-EA-TB host are suggested to be responsible for retention and relatively slow leaching processes. Electrocatalysis with immobilised Fe(CN)63−/4− is demonstrated for the oxidation of ascorbic acid.

scholarly journals Thermal Cross Linking of Novel Azide Modified Polymers of Intrinsic Microporosity—Effect of Distribution and the Gas Separation Performance

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1241 ◽  
Author(s):  
Silvio Neumann ◽  
Gisela Bengtson ◽  
David Meis ◽  
Volkan Filiz
Keyword(s):  
Gas Separation ◽  
Physical Aging ◽  
Gas Permeability ◽  
Time Lag ◽  
Polymer Chains ◽  
Separation Performance ◽  
Polymer Backbone ◽  
Cross Linkage ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

The synthesis of polymers of intrinsic microporosity (PIM) modified with azide groups, the cross linkage by nitrene reaction and their performance as gas separation membranes are reported. The azide modification of the spirobisindane units in the polymer backbone was done by post functionalization of methylated spirobisindane containing polymers. These polymers differ in distribution and concentration of the azide group containing spirobisindane units by applying perfectly alternating and randomly distributed copolymers along the polymer chains. To investigate the influence of concentration of the azide groups, additionally the homopolymer of methylated spirobisindane was synthesized and subjected to identical treatments and characterizations as both copolymers. Cross linkage by nitrene reaction was examined by different temperature treatments at 150, 200, 250 and 300 °C. Characterization of the new polymers was performed by NMR, SEC and FT-IR. Furthermore, the crosslinking process was investigated by means of solid state NMR, TGA-FTIR, DSC and isoconversional kinetic analysis performed with TGA. Gas permeability of CO2, N2, CH4, H2 and O2 was determined by time lag experiments and ideal selectivities for several gas pairs were calculated. The two azide groups per repeating unit degrade during thermal treatments by release of nitrogen and form mechanically stable PIM networks, leading to an increase in gas permeability while selectivity remained nearly constant. Measured diffusivity and solubility coefficients revealed differences in the formation of free volume elements depending on distribution and concentration of the azide groups. Aging studies over about five months were performed and physical aging rates (βP) were evaluated with regard to the concentration and distribution of curable azide functionalities. Subsequently, the enhanced sieving effect during aging resulted in membrane materials that surpassed the Robeson upper bound in selected gas pairs.

scholarly journals Free Volume and Gas Permeation in Anthracene Maleimide-Based Polymers of Intrinsic Microporosity

Membranes ◽  
2015 ◽  
Vol 5 (2) ◽  
pp. 214-227 ◽  
Author(s):  
Muntazim Khan ◽  
Volkan Filiz ◽  
Thomas Emmler ◽  
Volker Abetz ◽  
Toenjes Koschine ◽  
...  
Keyword(s):  
Free Volume ◽  
Gas Permeation ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

scholarly journals Chemical modification of the polymer of intrinsic microporosity PIM-1 for enhanced hydrogen storage

Adsorption ◽  
2020 ◽  
Vol 26 (7) ◽  
pp. 1083-1091
Author(s):  
Mi Tian ◽  
Sébastien Rochat ◽  
Hamish Fawcett ◽  
Andrew D. Burrows ◽  
Christopher R. Bowen ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Surface Area ◽  
Hydrogen Adsorption ◽  
Sorption Properties ◽  
Bet Surface Area ◽  
Polymer Modification ◽  
Gas Sorption ◽  
Chemically Modified ◽  
Polymer Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

Abstract A detailed investigation has been carried out of the pre-polymerisation modification of the polymer of intrinsic microporosity PIM-1 by the addition of two methyl (Me) groups to its spirobisindane unit to create a new chemically modified PIM-1 analogue, termed MePIM. Our work explores the effects of this modification on the porosity of PIM-1 and hence on its gas sorption properties. MePIM was successfully synthesised using either low (338 K) or high (423 K) temperature syntheses. It was observed that introduction of methyl groups to the spirobisindane part of PIM-1 generates additional microporous spaces, which significantly increases both surface area and hydrogen storage capacity. The BET surface area (N2 at 77 K) was increased by ~ 12.5%, resulting in a ~ 25% increase of hydrogen adsorption after modification. MePIM also maintains the advantages of good processability and thermal stability. This work provides new insights on a facile polymer modification that enables enhanced gas sorption properties.

scholarly journals Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

2015 ◽  
Vol 7 (1) ◽  
pp. 70-78 ◽  
Author(s):  
Sunyhik D. Ahn ◽  
Adam Kolodziej ◽  
Richard Malpass-Evans ◽  
Mariolino Carta ◽  
Neil B. McKeown ◽  
...  
Keyword(s):  
Substrate Selectivity ◽  
Polymer Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

The enhancement of chain rigidity and gas transport performance of polymers of intrinsic microporosity via intramolecular locking of the spiro-carbon

2016 ◽  
Vol 52 (39) ◽  
pp. 6553-6556 ◽  
Author(s):  
Jian Zhang ◽  
Hong Kang ◽  
Jacob Martin ◽  
Shouhai Zhang ◽  
Sylvie Thomas ◽  
...  
Keyword(s):  
Gas Transport ◽  
Membered Ring ◽  
Pivot Point ◽  
Chain Rigidity ◽  
New Strategy ◽  
Polymers Of Intrinsic Microporosity ◽  
Intrinsic Microporosity

We present a new strategy to improve the rigidity of PIM-1 through the introduction of 8-membered ring locking into the flexible spiro-carbon pivot point to produce a more rigid interlocked polycyclic structure.

scholarly journals Redox reactivity at silver microparticle—glassy carbon contacts under a coating of polymer of intrinsic microporosity (PIM)

2017 ◽  
Vol 21 (7) ◽  
pp. 2141-2146 ◽  
Author(s):  
Daping He ◽  
Erwan Rauwel ◽  
Richard Malpass-Evans ◽  
Mariolino Carta ◽  
Neil B. McKeown ◽  
...  
Keyword(s):  
Glassy Carbon ◽  
Polymer Of Intrinsic Microporosity ◽  
Redox Reactivity ◽  
Intrinsic Microporosity
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