Designed channels in thin benzimidazole-linked polymer membranes for hot H2 purification

High performance H2-selective polymer membranes are needed for hot H2 purification. Here, we have developed a series of 50 nm thick benzimidazole-linked polymer (BILP) membranes. H2-selective channels are designed in the membranes on the basis of synergistic effect of controllable formation of benzimidazole rings and precise manipulation of spacing among polymer chains. Highly-selective BILP membranes provide H2/CO2 selectivity up to 56.3 (with a corresponding H2 permeance of 127 GPU). H2 permeance up to 439 GPU (with a corresponding selectivity of 28.5) is delivered by highly-permeable BILP membranes. The superior performance far exceeds the upper bounds of traditional polymer membranes. In addition, the membranes possess outstanding thermal (e.g., 300 °C) and pressure resistance.