High performance polybenzimidazole based asymmetric hollow fibre membranes for H2/CO2 separation

We demonstrated for the first time the development of polybenzimidazole (PBI) based asymmetric hollow fibre membrane for H-2/CO2 separation at high temperatures. High molecular weight PBI was synthesised in-house by a solution polycondensation method. Hollow fibre membranes were fabricated by conventional dry-jet wet spinning technique. Defect free asymmetric PBI hollow fibre membranes were successfully produced, which eliminated the step of silicone rubber coating and were tested in the high temperature range of 100-400 degrees C. The effect of bore fluid chemistry was found to have a significant effect on the morphology as well as gas performance of the hollow fibre membranes. Suppressing the formation of macrovoids was found to show improvement in the mechanical properties of the fibres produced. The PBI fibres showed an increment in H-2 permeance with up to similar to 8 folds, but with relatively small increment in CO2 permeance of up to similar to 2 folds at 400 degrees C. Present PBI hollow fibre membranes showed H-2 permeance of about 2.6 x 10(-6) cm(3) (STP)/cm(2) s cmHg and H-2/CO2 selectivity of about 27. Ability to show the good separation characteristics at elevated temperatures depicts the potential of the present high performance PBI membranes for high temperature applications. (C) 2011 Elsevier B.V. All rights reserved.