A new class of self-forming membrane has been shown capable of separating carbon dioxide from a gas mixture. By operating as a coffee filter, it allows harmless gases, such as nitrogen, to escape into the atmosphere and allows carbon dioxide to be processed separately.
The team of researchers from UCL (University College London) and the University of Newcastle believe that the system may be applicable for use in carbon dioxide separation processes, either to protect the environment or in reaction engineering.
By growing the expensive part of the membrane, made of silver, during the operation of the membrane, they dramatically reduced the demand for silver and the cost of the membrane. The work is published in the journal Energy and Environmental Science.
Co-author Professor Paul Shearing (UCL Chemical Engineering) said in a statement: “Over the past ten years, we have established sophisticated tools for X-ray imaging in the Electrochemical Innovation Lab, which enable us to view internal materials and devices during operation : Here we are we have applied these techniques to new self-forming membranes, which will play a key role in decarbonization. “
Co-author Dr. Greg Mutch of Newcastle University said: “We don’t build the entire silver membrane, instead we add a small amount of silver and grow it inside the membrane, adding the functionality we wanted. The most important thing is that the performance of the membrane is at the level required to be competitive with existing carbon capture processes; in fact, it would probably reduce the size of the required equipment significantly and potentially reduce operating costs. “
Carbon dioxide emissions are the main driver of climate change. Currently, our climate is approximately 1 ° C warmer than in pre-industrial times. We have already emitted enough carbon dioxide to heat the planet beyond 1.5 ° C (there is a delay between emissions and warming), and we have international agreements to ensure that we do not exceed 2 ° C.
Warming above 2 ° C will have disastrous consequences, including impacts on human health, food availability, large-scale migration and our environment. We urgently need new materials and processes that reduce the amount of carbon dioxide that we emit into the atmosphere; These technologies are called carbon capture and storage (CCS).
Although we are making great efforts with renewable energy and electric vehicles, the world is still predominantly fueled by fossil fuels and it is highly unlikely that we will be able to reduce that contribution in time to limit warming to less than 2 ° C.
Furthermore, major modeling exercises, such as those of the Intergovernmental Panel on Climate Change, have repeatedly demonstrated that the most cost-effective way to curb global warming always involves a significant amount of CCS (in combination with, for example, renewable energy).
THE SELF-FORMING MEMBRANE
In a never-before-tried method, granular and tubular aluminum oxide supports were used to grow the silver-based membrane. Silver was added to the support, and the conditions experienced during the operation forced the silver to grow inside the support, giving the membrane a higher yield.
Using X-ray computed tomography at the UCL Electrochemical Innovation Laboratory, the team was able to observe the interior of the membrane and confirm that the penetration of CO2 and O2 stimulated the self-assembly of silver dendrites.
Importantly, membrane performance was demonstrated through permeation measurements at the level required to be competitive with existing carbon capture processes. Membrane permeability was an order of magnitude greater than required, and CO2 flux was the highest reported for this class of membrane.
Mutch added: “These savings are significant: the cost of carbon capture is one of the key factors limiting the absorption of the technology. There is a common metric for membrane performance: the ‘upper limit’. Like our membrane It is based on a single transport mechanism, we avoid the limitations of most membrane materials and go far beyond the upper limit. “
