Polybenzimidazole composite membranes for high temperature synthesis gas separations

High temperature gas separation techniques are of great interest for reduction in green-house gas emissions from hydrocarbon fuels such as natural gas, coal or biomass used in power and chemical industry. In this work, a robust industrially viable polybenzimidazole (PBI)/stainless steel composite membrane is developed and evaluated for syngas separations at elevated temperatures for H2 production. A single tube laboratory scale PBI membrane module is tested for H2/CO2 perm-selectivity in pure and simulated dry syngas environments at industrially relevant operating conditions. Additionally, the effects of pressure and temperature on membrane performance are evaluated. The PBI composite membrane demonstrated exceptional long term thermo-chemical stability in the syngas environment even in the presence of H2S and excellent separation performance for H2 over the other syngas components. The H2 permeance and H2/CO2 selectivity for the PBI composite membrane in simulated dry syngas was recorded at 7 GPU (approximately, 88 barrer) and 47, respectively. In comparison to the other H2-selective polymeric membranes, the PBI composite membraneʹs performance exceeded the 2008 Robeson upper bound for the H2/CO2 permeability versus selectivity.