Materials for separation membranes in hydrogen and oxygen production and future power generation

Future fossil fuel power generation is likely to include technologies which increase process efficiency and reduce its impact on the environment, for example, CO2 sequestration. Some of the key technologies identified for clean coal and natural gas combustion to produce power or hydrogen or both include O2 generation/separation, H2 and CO2 separation. Hydrogen is considered as a potentially excellent substitute for transport fuels due to the concern over dwindling oil reserves and global warming. This paper discusses various separation processes that may be used in the industrial production of hydrogen from fossil fuels, with an emphasis on membrane separation technologies. Membrane separation has the advantage over other separation methods in that it is simple and potentially less energy intensive. Depending on the particular separation process utilised, however, the membrane materials can differ substantially. The materials used for H2, O2 and CO2 separation are discussed and the major similarities and differences between the membranes highlighted. Critical design aspects of the membrane such as multiple phase design, nano-structure control, the need for surface layers and fabrication processes are also reviewed as they represent the areas where most research and development effort is likely to be directed in the future.