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Author: Ozkan, NecatiSubject: Polybenzimidazole

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    Article
    Citation - WoS: 92
    Citation - Scopus: 103
    Fabrication and Characterization of Cross-Linked Polybenzimidazole Based Membranes for High Temperature Pem Fuel Cells
    (Pergamon-elsevier Science Ltd, 2017) Ozdemir, Yagmur; Ozkan, Necati; Devrim, Yilser
    In this study different types of crosslinked polybenzimidazole (PBI) membranes were compared as high temperature proton exchange membrane fuel cells (HT-PEMFC). Cross-linking of PBI was performed with different cross-linkers including bisphenol A diglycidyl ether (BADGE), ethylene glycol diglycidyl ether (EGDE), alpha-alpha'-dibromo-p-xylene (DBpX), and terephthalaldehyde (TPA). The crosslinked membranes have been characterized by thermogravimetric analysis, scanning electron microscopy, acid uptake and impedance analyses. The crosslinking of the PBI polymer matrix helps to improve the acid retention properties. PBI/BADGE presented the highest acid retention properties. Proton conductivities of the membranes were comparable to that of commercial membranes. Conductivity values up to 0.151 S.cm(-1) were obtained at 180 degrees C with PBI/DBpX membranes. Gas diffusion electrodes (GDE) were fabricated by an ultrasonic coating technique with 0.6 mg Pt.cm(-2) catalyst loading for both anode and cathode. The crosslinked membranes were tested in a single HT-PEMFC with a 5 cm(2) active area at 165 degrees C without humidification. PBI/BADGE crosslinked membranes demonstrated stability and high performance on single cell HT-PEMFC tests. The maximum power density for PBI/BADGE was determined as 0.123 W. cm(-2). As a result, the experimental results suggested that the PBI/ BADGE and PBI/DBpX cross-linked membranes are promising electrolyte options for HT-PEMFC. (C) 2017 Elsevier Ltd. All rights reserved.
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    Article
    Citation - WoS: 38
    Citation - Scopus: 41
    Preparation of Polybenzimidazole/Zif-8 and Polybenzimidazole/Uio-66 Composite Membranes With Enhanced Proton Conductivity
    (Pergamon-elsevier Science Ltd, 2022) Eren, Enis Oguzhan; Ozkan, Necati; Devrim, Yilser
    Metal-organic frameworks (MOFs) are considered emerging materials as they further improve the various properties of polymer membranes used in energy applications, ranging from electrochemical storage and purification of hydrogen to proton exchange membrane fuel cells. Herein, we fabricate composite membranes consisting of polybenzimidazole (PBI) polymer as a matrix and MOFs as filler. Synthesis of ZIF-8 and UiO-66 MOFs are conducted through a typical solvothermal method, and composite membranes are fabricated with different MOF compositions (e.g., 2.5, 5.0, 7.5, and 10.0 wt %). We report a significant improvement in proton conductivity compared with the pristine PBI; for example, more than a three-fold increase in conductivity is observed when the PBI-UiO66 (10.0 wt %) and PBI-ZIF8 (10.0 wt %) membranes are tested at 160 degrees C. Proton conductivities of the composite membranes vary between 0.225 and 0.316 S cm(-1) at 140 and 160 degrees C. For the comparison, pure PBI exhibits 0.060 S cm(-1) at 140 degrees C and 0.083 S cm(-1) at 160 degrees C. However, we also report a decrease in permeability and mechanical stability with the composite membranes. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Article
    Citation - WoS: 14
    Citation - Scopus: 14
    High-Temperature Electrochemical Hydrogen Separation From Reformate Gases Using Pbi/Mof Composite Membrane
    (Pergamon-elsevier Science Ltd, 2023) Durmus, Gizem Nur Bulanik; Eren, Enis Oguzhan; Devrim, Yilser; Colpan, C. Ozgur; Ozkan, Necati
    In this paper, the high-temperature electrochemical Hydrogen (H2) purification perfor-mance of a polybenzimidazole/UIO-66 metal-organic framework (PBI/UIO-66) membrane is investigated and analyzed at different values of current, temperature, and reformate feed composition. Purification measurements show that a significant reduction in gas impu-rities can be obtained. In the performance tests, three different ratios of reformate gas (RG) (H2:carbon dioxide (CO2):carbon monoxide (CO)) as RG-1= (75:25:0), RG-2= (75:22:3), and RG-3= (95:0:5) were used. The highest purification values were observed at 160 & DEG;C as 99.999%, 99.931%, and 99.708% for RG-1, RG-2, and RG-3, respectively. The obtained results show that an electrochemical H2 purification (ECHP) based on PBI/UIO-66 composite membrane is promising for H2 purification.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.