Microporous Polybenzimidazole Research Articles

Correction: Rational design of microporous polybenzimidazole framework for efficient proton exchange membrane fuel cells

Correction for ‘Rational design of microporous polybenzimidazole framework for efficient proton exchange membrane fuel cells’ by Harilal et al., J. Mater. Chem. A, 2022, https://doi.org/10.1039/d2ta00734g.

Rational design of microporous polybenzimidazole framework for efficient proton exchange membrane fuel cells

Ion-conducting membranes from three-dimensional iptycene-based polybenzimidazoles developed for the first time to fabricate efficient proton exchange membranes with ordered nanochannels, enabling ultrafast and stable anhydrous proton conduction.

Molecular engineering of intrinsically microporous polybenzimidazole for energy-efficient gas separation

Polybenzimidazole (PBI) is a high-performance polymer that exhibits high thermal and chemical stability. However, it suffers from low porosity and low fractional free volume, which hinder its application as separation material. Herein, we demonstrate the molecular engineering of gas separation materials by manipulating a PBI backbone possessing kinked moieties. PBI was selected as it contains NH groups which increase the affinity towards CO2, increase sorption capacity, and favors CO2 over other gasses. We have designed and synthesized an intrinsically microporous polybenzimidazole (iPBI) featuring a spirobisindane structure. Introducing a kinked moiety in conjunction with crosslinking enhanced the polymer properties, markedly increasing the gas separation performance. In particular, the BET surface area of PBI increased 30-fold by replacing a flat benzene ring with a kinked structure. iPBI displayed a good CO2 uptake of 1.4 mmol g−1 at 1 bar and 3.6 mmol g−1 at 10 bar. Gas sorption uptake and breakthrough experiments were conducted using mixtures of CO2/CH4 (50%/50%) and CO2/N2 (50%/50%), which revealed the high selectivity of CO2 over both CH4 and N2. The obtained CO2/N2 selectivity is attractive for power plant flue gas application requiring CO2 capturing materials. Energy and process simulations of biogas CO2 removal demonstrated that up to 70% of the capture energy could be saved when iPBI was used rather than the current amine technology (methyl diethanolamine [MDEA]). Similarly, the combination of iPBI and MDEA in a hybrid system exhibited the highest CO2 capture yield (99%), resulting in nearly 50% energy saving. The concept of enhancing the porosity of PBI using kinked moieties provides new scope for designing highly porous polybenzimidazoles for various separation processes.

Synthesis of a microporous poly-benzimidazole as high performance anode materials for lithium-ion batteries

Heteroatom-rich two-dimensional graphene-like structure polymers are highly demanded as high-performance anode materials for lithium ion batteries. Here, a new microporous poly-benzimidazole (MPBI) is accomplished by a condensation reaction between pyromellitic acid and 1,2,4,5-tetraaminobenzene in polyphosphoric acid medium. After heat-treatment at 550 °C, the integrated frame structure of the obtained MPBI-550 remains unchanged without the residual edge groups. Due to the holey pore framework, nitrogen-rich aromatic rings and two-dimensional graphene-like structure, MPBI-550 is suitable for lithium-ion battery anode. It exhibits a remarkable long cycling life, high reversible capacity of 700 mAh g−1 (at 1 A g−1) after 500 cycles and a good rate performance. Such a low-cost and high-performance material constitutes a step towards the design and manufacture of functional anode materials for next generation lithium-ion batteries.

Layered-structure microporous poly(benzimidazole)-loaded imidazole for non-aqueous proton conduction

In this work, a microporous polybenzimidazole was designed and synthesised.

Highly gas permeable and microporous polybenzimidazole membrane by thermal rearrangement

This manuscript reports, for the first time, a new synthesis route to prepare thermally rearranged microporous polybenzimidazole (TR-PBI) membranes, exhibiting exceptionally highly permeable characteristics to small gas molecules as well as excellent molecular sieving properties. Generally, common PBIs have very rigid, well-packed structures due to their strong intermolecular interactions, resulting in very low gas permeation properties which prevent PBIs from applying in gas separation. Here, we demonstrate new synthesis route to obtain highly permeable TR-PBI membranes having microporous characters (i.e., high fractional free volume), prepared by the alkaline hydrolysis of polypyrrolone followed by simple thermal treatment.

Removal of uranium from acidic sulfate solution by ion exchange on poly(4-vinylpyridine) and polybenzimidazole in protonated sulfate form

Microporous polybenzimidazole (PBI) of 0.25–0.50 mm spherical bead size from Celanese and spherical crosslinked poly(4-vinyl-pyridine), Reillex 425 PVP, of diameter 0.5–1.5 mm from Reilly Industries Inc. were used in the protonated sulfate form for the sorption of uranium from acidic sulfate solution and compared with conventional strong-acid and strong-base ion-exchange resins Dowex-50(H+) and Dowex-1 (SO42−) for the same application. Both PBI(H2SO4) and PVP(H2SO4) exhibit significantly greater acid tolerance than both Dowex-50(H+) and Dowex-1(SO42−), on which the uranium uptake drops drastically at low pH with the result that at pH values below 1.0, PVP(H2SO4) has considerably greater uranium sorption than both Dowex-50(H+) and Dowex-1(SO42−). The uranium capacity of PBI(H2SO4) is, however, less than half that of PVP(H2SO4). The protonated PVP also has considerably greater salt tolerance than the Dowex resins and exhibits high uranium selectivity in the presence of large excesses of NaCl and Na2SO4, while in comparison the uranium selectivity on Dowex-1(SO42−) is sharply reduced by NaCl and that on Dowex-50(H+) by both NaCl and Na2SO4. Thus, for uranium sorption against high salt background, PVP(H2SO4) exhibits higher capacity than the Dowex resins. Of the three resins, however, PVP(H2SO4) has the slowest sorption kinetics, the approximate half times for exchange being 4, 21 and 65 min for Dowex-50(H+), Dowex-1(SO42−) and PVP(H2SO4), respectively. The sorbed uranium species can be stripped with HCl, H2SO4, NaCl or Na2SO4 which give different stripping rates. The fastest stripping for all the sorbents is obtained with HCl.

The Effect of Porous Support Composition and Operating Parameters on the Performance of Supported Liquid Membranes

Abstract Factors, such as porous support composition and operating parameters, that influence the performance of supported liquid membranes (SLMs) were investigated. SLMs of varying porous support compositions and structures were studied for the transport of metal ions. A microporous polybenzimidazole support was synthesized and prepared in the form of an SLM. This SLM, containing the selective extractant di-(2-ethylhexyl)phosphoric acid, was evaluated for the transport of copper and neodymium. Dramatically improved performance over that of commercially available membranes was found in tests for removing the metal ions from solution. Metal ion transport reaches near completion in less than 3 h, whereas Celgard-polypropylene and Nuclepore-polycarbonate reaches only 50% completion even after 15 h. The transport driving force for acidic extractants is a pH gradient between the feed and strip solutions. Polybenzimidazole, an acid- and radiation-resistant polymer, has two protonatable tertiary nitrogens per re...

New chelating resins based on polybenzimidazole. Selective sorption of copper(II) from ammoniacal media on resin with anchored l-cysteine

Microporous polybenzimidazole (PBI) of 250–500 μm bead size has been epoxidized and subsequently reacted with l-cysteine in the presence of a phase-transfer catalyst at room temperature to obtain a sorbent having anchored l-cysteine, EPBI(Cyst). The sorption of Cu(II), Ni(II), Co(II), and Zn(II) in mildly acidic and ammoniacal solutions has been measured under comparable conditions on EPBI(Cyst) and Dowex 50W-X8(H +) resins. While the latter shows no appreciable difference in sorption of the four metals in acidic and ammoniacal media and has 40–60 % selectivity for copper(II) over the other three, EPBI(Cyst) shows a threefold increase in copper sorption and more than 90% copper selectivity over the other metals in ammoniacal media, compared to mildly acidic media. The copper binding constant and saturation capacity of EPBI(Cyst) in ammoniacal media decrease only slowly beyond pH 11.6 with the result that the resin shows significant sorption of Cu(II) even in strongly ammoniacal solutions. The sorbed copper is stripped with HCl relatively easily. The copper sorption kinetics on EPBI(Cyst) is unusually fast in ammoniacal media with more than 90 % of equilibrium sorption being attained in one minute.

Polybenzimidazole resin based new chelating agents uranyl ion selectivity of resins with immobilized glyoxal-bis-2-hydroxyanil and salicylaldehyde-ethylenediimine

Microporous polybenzimidazole (PBI) of 250–500 μm spherical bead size from Celanese has been reacted with epichlorohydrin and sodium hydroxide and the resulting epoxidized product (EPBI) further reacted with glyoxal-bis-2-hydroxyanil (GHA) and salicylaldehyde-ethylenediimine (SED) at ordinary temperatures, using a quaternary ammonium salt as the phase-transfer catalyst. The resulting new sorbents EPBI(GHA) and EPBI(SED) have been compared with the base resin PBI and the conventional ion-exchange resins Dowex 50W-X8(H +) and Dowex 1-X8(SO 4 2−) in respect of uranyl sorption in sulfate system. In UO 2SO 4 solution at pH 4.7, the saturation capacities (mmol U/g dry wt. of resin) of the five resins, in the aforesaid order, are 1.03, 1.20, 2.79, 2.10 and 1.35, respectively. Both EPBI(GHA) and EPBI(SED), however, show greater sorption capacities than PBI at low substrate concentrations of uranium (< 60 mg U/L) due to their significantly higher binding constants than PBI. Both PBI and its derivatives EPBI(GHA) and EPBI(SED) have considerably greater salt tolerance than the Dowex resins. Thus, in the presence of twenty fold molar equivalents of sodium ions, the uranium selectivities of Dowex 50W-X8(H +) and Dowex 1-X8(SO 4 2−) are, respectively, 0.32 and 0.50 in NaCl solution and 0.15 and 0.87 in Na 2SO 4 solution. In comparison, PBI and its derivatives have selectivities of 1.0 in NaCl and 0.75–0.80 in Na 2SO 4, thus yielding greater uranium sorptions than the Dowex resins against a high salt background.

Sorption of aqueous sulfur dioxide on polybenzimidazole and poly(4-vinyl pyridine)

The two relatively new, weak-base commercial polymeric sorbents, namely, microporous polybenzimidazole (PBI) and macroporous poly(4-vinyl pyridine) (PVP) have been compared with regard to sorption of aqueous sulfur dioxide. The sorption behaviour of PBI is also compared with that of its amine derivatives prepared by epoxidation of the resin and subsequent aminolysis with ethylene diamine and diethylene triamine. PBI shows greater saturation capacity for SO 2(aq) sorption than PVP despite having lower proton capacity than PVP in strong acids while at low concentrations of SO 2(aq), PVP exhibits greater equilibrium sorption than PBI. Interestingly, PBI, though microporous, has considerably faster kinetics for SO 2(aq) sorption than macroporous PVP, with particle phase diffusivity nearly twice that of the latter. Aminolysis of PBI does not improve the SO 2(aq) sorption capacity, as it actually decreases, on weight basis, the nitrogen content and proton capacity of the resin.

Polybenzimidazole resin-based new chelating agents. Uranyl and ferric ion selectivity of resins with anchored dimethylglyoxime

Microporous polybenzimidazole (PBI) of 250–500 μm spherical bead size from Celanese has been reacted with epichlorohydrin and sodium hydroxide and the resulting epoxidized product (EPBI) further reacted with dimethylglyoxime (DMG) using a quaternary ammonium salt as the phase transfer catalyst, to obtain a new sorbent EPBI (DMG) having high sorption capacity for UO 2 2+ (172 mg U/g dry weight of resin) and for Fe 3+ (188 mg Fe/g dry wt of resin). The sorption of UO 2 2+ is maximum in weakly acidic or neutral solutions (pH 5–7), falling sharply both at lower and higher pH, while the uptake of Fe 3+, sorbed mainly as anionic complexes, is relatively unaffected by pH in HCl and H 2SO 4 media. Among the transition metal ions tested, Co 2+ has the highest binding constant for sorption on the resin, followed by Fe 3+, Cu 2+, Ni 2+, Mn 2+ and UO 2 2+, in that order, although the sorption capacities of all these metal ions, except Fe 3+ and UO 2 2+, are rather poor. The sorbed UO 2 2+ is readily stripped by 1 N HCl and 10% (w/v) ammonium carbonate solution while removal of the sorbed Fe 3+ complexes is considerably more difficult, requiring strong phosphoric acid solution for effective stripping.

Polybenzimidazole resin-based new chelating agents. Ferric ion selectivity of resins with immobilized oligoamines

Microporous polybenzimidazole of 250–500 μm bead size from Celanese has been epoxidized and subsequently aminolyzed with ethylenediamine and diethylenetriamine to obtain sorbents having high capacity, selectivity and sorption rate for ferric ion from acidic sulfate solutions. The ferric ion sorption capacity of these sorbents is more than twice that obtained with normal chelating resins. The chelation properties of the new sorbents can be used as a means of removing the ferric ion selectivity from mixtures in acidic sulfate solution containing a wide range of mono- and multivalent metal ions, including some which normally form strong chelate complexes.