Electrochemical Hydrogen Separation from Reformate Using High-Temperature Polybenzimidazole (PBI) Membranes: The Role of Chemistry

Various phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes, para-PBI, m/p-PBI, and meta-PBI, were prepared via the poly­(phosphoric acid) (PPA) process. These three membranes showed high levels of PA (10–32 PA/PBI repeat unit (r.u.)) and proton conductivity (0.14–0.26 S/cm at 180 °C) as compared with a conventionally imbibed meta-PBI membrane (6 PA/PBI r.u. and 0.08 S/cm at 180 °C). By controlling chemistry and increasing the polymer solid content to ∼18 wt %, m/p-PBI and meta-PBI membranes exhibited significantly improved creep resistance (99.6% with