Gas Separation Membranes
IEK-1 also develops ceramic membranes for gas separation, an area in which the development priorities have considerably expanded in the past few years.
While at first, applications in advanced fossil-fired power plants (carbon capture technology) were the focus, nowadays, other energy-intensive industrial processes such as the steel, glass, or cement industry have also become priorities. Another focus is increasing efficiency in processes of the chemical and petrochemical industry by developing membrane reactors with energetically favourable process intensification.
The cooperation between research, universities, and industry has continuously been expanded in various third-party-funded projects. In addition to the well-known portfolio topic MEM-BRAIN (gas separation membranes for energy-efficient processes), the EC-FP7 project GREEN-CC, which was initiated in late 2013, is worth a special mention: The project, which involves 14 partners and total funding of € 8.6 million, is coordinated by Forschungszentrum Jülich (IEK-1). Together with partners from European research and industry, membranes are being developed for oxygen separation. An Australian partner is also involved in the project.
For each separation task, different ceramic membranes are being developed at IEK-1. Among the inorganic membrane types, a distinction is made between dense ion-conducting or mixed-conducting membranes and microporous crystalline or amorphous membranes.
For ion-conducting oxygen separation membranes, one focus is on developing a module consisting of scalable thin-film membranes of 10x10 cm², stacked one on top of the other.
The material of choice for developing high-performance materials was BSCF. The next step will be a proof of concept for these components. Another priority is the improvement of membrane stability while retaining the desired functional properties. Asymmetric BSCF or LSCF membranes are investigated with external partners to find out whether they are suitable for intensifying chemical processes, for example to efficiently provide oxygen for catalytic conversions, such as converting methane to hydrocarbons. These activities are consistently being expanded with external partners.
For proton-conducting membranes, based on barium cerates and zirconates as well as lanthanum tungstates, experiments were conducted concerning proton transport, stability, and hydrogen separation from gas mixtures. By introducing appropriate doping, the performance data were considerably improved. Thus, the hydrogen transport of certain thin-film structures was improved by almost one order of magnitude. Utilization of other suitable rare earth elements to further increase performance is another objective.
Membranes based on silicon dioxide exhibit excellent H2/CO2 or H2/N2 separation capabilities. By introducing stable mesoporous ZrO2 intermediate layers, the stability was improved in moist atmospheres, while retaining good separation characteristics. This type of membrane is used in industry (Pervatech) for pervaporation processes, for example for dehydrating alcohol. Microporous gas separation membranes usually have a graded structure, i.e. a substrate with relatively large pores is the starting point, and successive layers with finer particles are applied to it. The membrane layer deposited on this carrier structure is only a few nanometres thick. The following illustration shows the entire structure of a graded gas separation membrane.
All membrane types need to be further developed with regard to permeability, selectivity and stability. IEK-1 is concerned with the development and production of new materials and membrane coatings using different process technologies. In addition to purely developing materials with the aim of supplying stable functional materials, we conduct other research activities in the area of microstructuring (for example, for gas flow optimization) and component manufacture (scalable membrane components for use in proof-of-concept modules).
GREEN-CC (Grant 608524) (2015)
Graded membranes for energy efficient new generation carbon capture process
HETMOC (Grant 268165) (2016)
Highly Efficient Tubular Membranes for Oxy-Combustion
HETMOC is a FP7 project funded by the European Union
Efficiency Improvement of Oxygen-Based Combustion.