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 H-2 production. A single tube laboratory scale PBI membrane module is tested for H-2/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 H-2 over the other syngas components. The H-2 permeance and H-2/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 H-2-selective polymeric membranes, the PBI composite membrane's performance exceeded the 2008 Robeson upper bound for the H-2/CO2 permeability versus selectivity. (c) 2012 Elsevier B.V. All rights reserved.