Self-healing ceramic membranes with increased lifetime for CO2 capture in industrial processes and power production

Gas separation technologies making use of robust and efficient ceramic mixed conducting (oxide ion, electron or proton, electron) membranes have the potential of significant cost reduction and higher efficiency of CCS in power production and industrial processes. However, a number of critical challenges must be addressed to achieve breakthrough development in cost, lifetime, and performance of these membranes. Production may need clean rooms to avoid pinholes from dust, and the high operating temperature that gives high gas permeation flux is also accompanied by tendency of creep and cracking due to thermal stresses. The SEALEM project aims at a radical improvement of lifetime and performance of ceramic membranes by developing ground-breaking self-healing ceramic membranes. The project was led by UiO, with collaboration from SINTEF and NTNU. It educated one PhD candidate and trained one post-doctoral researcher. Two healing mechanisms ? chemical creep closure (CCC) and reaction growth repair (RGR) were investigated in SEALEM, both based on enhanced cation diffusion through an opening in a dense ceramic membrane, and the driving force from creep coming either the oxygen activity gradient or from the reactivity between solid components at both sides of the membrane. We have tested several combinations of materials in order to identify materials systems with the desired healing properties. Some combinations covering both CCC and RGR mechanisms have been demonstrated to be operational: They seal pinholes or densify a porous membrane. The RGR can also be extended to actually grow the membrane in situ from presence of two porous reactive layers. If we can implement such membrane architectures in gas separation technology it will drastically reduce the membrane fabrication costs and increase their lifetime. A patent application was filed by all three partner institutions in 2016 and is being published now in 2017. The project has also been undertaking fundamental studies of central materials properties such as thermo-chemical expansion and surface diffusion rates, as part of the PhD at NTNU. These parameters are essential in order to model lifetime and performance of the membranes. Instead of heating the membranes to the operating temperature by an enclosing furnace, the tubes may be internally heated by an electric current. Internal heating experiments have been made on two tube architectures and it is found that both can be internally heated to 800-900°C. Furthermore, gas permeation experiments of internally heated membranes on porous support have been conducted, indicating that such membranes can be operated with ohmic heating as well. Finally, we have designed and built a sample holder for tubular membranes which will enable ohmic heating of the tubes and simplify the process of testing and replacing individual tubular membranes. This type of module has been extended in an EU project coordinated by UiO and is under IPR protection there. The partners are now seeking international and industry partners for further development, implementation, and exploitation of the results and IPR from the project.

Membranes technology making use of robust and efficient ceramic mixed conducting (oxide ion, electron or proton, electron) membranes have the potential for significant cost reduction and higher efficiency of CCS in power production and industrial processe s. However, a number of critical challenges must be addressed to achieve breakthrough development in lifetime and performance of these membranes, as high flux is also accompanied by less desirable increasing cation mobility, which results in faster degrad ation rate. The SEALEM project aims at a radical improvement of lifetime and performance of ceramic membranes by developing ground-breaking self-healing ceramic membranes with high flux from increased surface kinetics and fast bulk diffusion. Self-healing membranes would allow cheaper production of membranes, major increase in lifetime, and reduced operational costs, as faults created upon operation or manufacturing would repair themselves. Two healing mechanisms termed Reaction Growth Repair and Chemical Creep Closure are IPRs of UiO and will be investigated in SEALEM. This is a pioneering work which builds on knowledge on cation diffusion. Model for lifetime prediction in SEALEM will be created from an integrated knowledge on surface kinetic, kinetic de mixing and chemical creep and stresses in membranes operating in a chemical potential gradient set by industrial applications using both theoretical and experimental approaches. This model will be used for robust assessment of membrane technology in power and industrial cycles in the project. SEALEM will further develop novel module designs with cold seals and internal heating of membranes. The project lasts 3 years and is led by UiO in collaboration with SINTEF and NTNU. It educates one PhD candidate and trains one post-doctoral researcher.