Polybenzimidazole (PBI) Cation-Exchange Membrane (Celazole, T=55 um) for High-Temperature Electroyzer and Fuel Cell, CHTEFCCEMPBIC

Celazole® PBI (Polybenzimidazole), originally developed by Celanese (now produced by PBI Performance Products), is the premier commercial standard for aromatic heterocyclic polymers. In electrochemical and membrane separation fields, Celazole PBI is widely deployed as a high-temperature proton exchange membrane (HT-PEM) and gas separation membrane capable of continuous operation across 120°C to >200°C. Its fundamental backbone—poly[2,2’-(m-phenylene)-5,5’-bibenzimidazole] (often called m-PBI)—features rigid, fully aromatic repeating units that impart exceptional thermal stability (Tg > 425°C), chemical inertness, and basic nitrogen sites for acid doping.

The key properties of the Celazole PBI membranes are: (1) Acid Doping for Anhydrous Proton Conduction: Pristine Celazole PBI is an electrical insulator. When soaked in concentrated phosphoric acid (H3PO4), the basic imidazole nitrogens (-N= and -NH-) form hydrogen-bonded networks with the acid. Protons hop via the Grotthuss mechanism along the acid chains. Unlike sulfonated fluoropolymers (e.g., Nafion), Celazole PBI does not require humidification to conduct protons, operating efficiently at 150°C--180°C under completely dry feed conditions. (2) Acid Doping Level (ADL) vs. Mechanical Robustness: Measured as moles of H3PO4 per PBI repeat unit (mol/PRU). Typical Target Range: 6 to 12 mol H3PO4/PRU, yielding a conductivity of 0.04 to >0.10 S/cm at 160°C.

The key application fields are: (1) High-Temperature PEM Fuel Cells (HT-PEMFC): (i) Reformed Methanol Fuel Cells (RMFC): Direct coupling with on-board methanol or natural gas reformers; high CO tolerance eliminates costly multi-stage water-gas shift (WGS) and preferential oxidation (PROX) purification reactors. (ii) Aviation & Marine APUs: Elevated operating temperatures allow compact, lightweight radiators without bulky humidification hardware. (2) Electrochemical Hydrogen Separation & Compression (EHC): Extraction of pure H2 directly from high-temperature syngas or industrial waste streams with simultaneous electrochemical pressurization (>50bar). (3) High-Temperature Gas Separation: Post-combustion CO2/N2 capture and pre-combustion H2/CO2 separation at elevated process temperatures where conventional polymeric gas membranes degrade.

Part Number	CHTEFCCEMPBIC (C-HTEFC-CEM-PBIC)
Chemical Structure
Appearance	Brown or Dark Brown
Membrane Thickness & Molecular Weight	T=55 um, Mw = 60000
Sheet Dimensions	(1) 10cm * 10cm (2) 20cm * 20 cm (3) 30cm * 20 cm Other large dimensions can be supplied upon request
Operation Temperature	150 °C for continuous operation, and the ultimate temperature is 300 °C
Pretreatment Status	Phosphoric acid pretreatment is required. Clean the membrane with DI H2O/ethanol for 10-20 min Immersed in 85-10% H3PO4 for 1-48 h at 80-120°C Rising with DI H2O for multiple times to remove free H3PO4 Dry the membrane at low temperature (<60°C) for 12-14 h
Proton Conductivity	~0.1 S/cm (at 160°C, anhydrous)
Acid Concentration for Operation	55 wt% (+/-4 wt%)
Package Grade	1 pcs/pack

References

(1）K. Likit-anurak, et al., Polybenzimidazole Membranes as Nafion Replacement in Aqueous HCl Electrolyzers, ACS Appl. Energy Mater. 2023, 6, 10, 5429–5434. 

(2) Q. Li, et al., PBI-Based Polymer Membranes for High Temperature Fuel Cells – Preparation, Characterization and Fuel Cell Demonstration, Fuel Cells, 2004, 4, 147-159.