Self-healing ceramic membranes with increased lifetime for CO2 capture in industrial processes and power production
Climit financing88% from the Research Council, 12% own financing
Project partnersUniversity of Oslo (UiO) SINTEF Materialer og kjemi NTNU
Project period2013 – 2017
Goal of the Project:
The SEALEM project aims at a radical improvement of lifetime and performance of ceramic gas separation membranes by developing ground-breaking self-healing mechanisms, better understanding of degradation phenomena based on chemical stresses and cation diffusion, and improving bulk transport and kinetics. The project educates one PhD candidate and trains one post-doctoral researcher.
The project contains five R&D sub-projects (SP) with the following technical content: SP1: Self-healing membranes: Manufacturing of model membranes and tubular membranes and investigation of two proprietary mechanisms for self-healing. SP2: Oxygen and hydrogen transport: Bulk transport and surface kinetics. SP3: Lifetime analysis: Measurement of cations diffusion, kinetic decomposition study, and evaluation of chemical stresses and effects on membrane integrity to perform lifetime analysis. SP4: Development of innovative prototype module: Design and components selection of new rig enabling in-situ heating, building and commissioning of single tube rig and assessment of single tube rig. SP5: Management, IPRs and dissemination: Overall management of the project, dissemination, networking and IPR handling.
Main outcomes for each SP are presented in Table 1 and details of the work are given below.
Sub-projects (SP) in SEALEM and main technical advantages:
SP1: Self-healing membranes
- Ground-breaking self-healing methods
- Tubular membranes with improved robustness
SP2: Oxygen and hydrogen transport
- Optimisation of surface kinetics in HTMs and OTMs thin film supported membranes
SP3: Lifetime analysis
- Integrated model for lifetime prediction of membranes in operation combining theoretical and experimental approaches
SP4: Innovative membrane module
- Development of single tube module with internal heating, cold seals, high pressure and high temperature operation
SP5: Management, IPRs and dissemination
- Dissemination and protection of results via patents, peer reviewed articles, presentation in international conferences
Membrane efficiency relates to a high flux density, which in turn is given by a high mixed (ambipolar) transport of ions and electrons. The membrane should be as thin as possible, but in order to utilise this, its surface kinetics must be fast. Additionally, the demands on robustness of the membrane increase as the membranes get thinner. This is firstly because the chemical potential differences over the membrane get distributed over a shorter length giving rise to higher chemical potential gradients and hence faster destructive processes related to cation diffusion. The latter are related to the so-called chemical creep, or walkout of the membranes, which sets the ultimate limitation of an otherwise well-behaving membrane. Difference in diffusion between cations may also lead to demixing and possibly decomposition of the compound when exposed to a chemical gradient, thereby leading to accelerated dysfunction and possibly breakdown of the membrane.
Another important hurdle for oxygen and hydrogen transport membranes arises from chemical stresses when the membrane material is exposed to two gases with different compositions. The oxygen transport membranes tend to expand on the side with lower oxygen content, and the hydrogen transport membranes tend to expand on the side with higher water vapour pressure. In both cases, this leads to mechanical stresses, which either relax due to creep or may lead to sub-critical crack growth and finally complete mechanical failure of the membrane.
Finally, a thin membrane has larger chance of pinholes, caused for instance by foreign particles, during manufacturing steps as well as by cation diffusion due to enhanced chemical gradients locally.
In order to have more robust membranes the project tests novel self-healing strategies and the first stages towards modules of tubes that tolerate high pressure gradients, have cold seals, can be heated internally, and replaced individually for prolonged module lifetime.
Results to date:
The project started medio 2013. To date (ultimo 2013) the first test rig and verifications with internal heating of tubes have been running and are promising, and self-healing experiments with the first materials candidates are underway.