University of Bayreuth has got chemists who have developed an uncanny material. It could make an important contribution to climate protection as well as sustainable industrial production.
We can separate greenhouse CO2 from industrial waste gases, natural gas, or biogas, and thereby made available for recycling, thanks to this development. The process itself is energy efficient and cost-effective.
Presentation of the structure and function of the material is in the journal Cell Reports Physical Science.
The European Commission presented “Green Deal” in 2019, calling for the next emissions of greenhouse gases within the EU to be reduced to zero by 2050. For sure, this needs innovation, particularly the ones that can separate and retain CO2 from waste gases and other gas mixtures so that it is not released into the atmosphere.
Development by Bayreuth chemists
Bayreuth chemists’ material has a fundamental advantage over previous separation processes. It’s capable of completely removing CO2 from gas mixtures without chemically binding CO2. These gas mixtures can be waste gases from industrial plants, but also natural gas or biogas.
The process can release carbon dioxide without great expenditure of energy, to be made available again as a resource for industrial production. Like a spacious storage tank, the new material can be filled with and emptied of carbon dioxide in an energy-efficient way.
In Bayreuth laboratories, it was designed in such a way as to only separate out CO2 and no other gas from the most varied gas mixtures.
“Our research team has succeeded in designing a material that fulfils two tasks at the same time. On the one hand, the physical interactions with CO2 are strong enough to free and retain this greenhouse gas from a gas mixture.
“On the other hand, however, they are weak enough to allow the release of CO2 from the material with only a small amount of energy,” states Martin Riess M.Sc., first author and doctoral researcher at the University of Bayreuth.
An inorganic-organic hybrid, the chemical basis of this new material is clay minerals consisting of hundreds of individual glass platelets. Each of them is only one nanometre thick, arranged precisely one above the other.
There are individual glass plates and between them are organic molecules that act as spacers. Their shape and chemical properties have been selected so that the pore spaces created are optimally tailored to accumulate CO2.
Only carbon dioxide molecules can go into the pore system of the material and stay there. on the other hand, methane, nitrogen, and other exhaust gas components must remain outside due to the size of their molecules.
Researchers at Bayreuth have used the so-called molecular sieve effect to increase the material’s selectivity for CO2. They are currently working on the development of a membrane system based on clay minerals, designed to allow the continuous, selective, and energy-efficient separation of CO2 from gas mixtures.
Laboratories at Bayreuth has enabled researchers to develop this hybrid material, thanks to their special measuring system. It allows precise determination of quantities of adsorbed gases and of the selectivity of the adsorbing material. Researchers are then able to reproduce industrial processes realistically.
“All criteria relevant to the evaluation of industrial CO2 separation processes have been completely fulfilled by our hybrid material. It can be produced cost-effectively, and stands to make an important contribution to reducing industrial carbon dioxide emissions, but also to the processing of biogas and acidic natural gas,” says Riess.
CO2 fuel can be more efficient because of a membrane
I’m thick on chemistry, and I know almost nothing about it. Turns out, there’s a water-conducting membrane that can transform carbon dioxide into fuel more efficiently.
A chemical called methanol is versatile, efficient, and a material for the production of countless products. And of course, CO2 is a greenhouse gas and the unwanted byproduct of many industrial processes.
Therefore, converting CO2 to methanol is one way to put the bad boys to good use.
Chemical engineers from Rensselaer Polytechnic Institute has demonstrated how to make that conversion process more efficient. In research published in Science, they use a highly effective separation membrane they produced.
The researchers said that this breakthrough could improve a number of industry processes that depend on chemical reactions where water is a byproduct.
For example, the chemical reaction responsible for the transformation of CO2 into methanol also produces water, which severely restricts the continued reaction. Well, the Rensselaer team set out to find a way to filter out the water as the reaction is happening, without losing other essential gas molecules.
They assembled a membrane made up of sodium ions and zeolite crystals that was able to carefully and quickly permeate water through small pores without losing gas molecules.
Miao Yu who led this research said, “The sodium can actually regulate, or tune, gas permeation. It’s like the sodium ions are standing at the gate and only allow water to go through. When the inert gas comes in, the ions will block the gas.”
Discovery of this membrane
Yu said that in the past, this type of membrane was susceptible to defects that would allow other gas molecules to leak out. However, his team developed a new strategy to optimize the assembly of the crystals, which eliminated those defects.
When they removed water effectively from the process, the team found that the chemical reaction was able to happen very quickly.
“When we can remove the water, the equilibrium shifts, which means more CO2 will be converted and more methanol will be produced,” said Huazheng Li, a postdoctoral researcher at Rensselaer and first author on the paper.
“This research is a prime example of the significant contributions Professor Yu and his team are making to address interdisciplinary challenges in the area of water, energy, and the environment.
“Development and deployment of such tailored membranes by Professor Yu’s group promise to be highly effective and practical,” said Deepak Vashishth, director of CBIS.
Looking ahead, the team is planning to develop a scalable process. They’re also working on building startup company that would allow this membrane to be used commercially to produce high purity methanol.
“In industry there are so many reactions limited by water. This is the only membrane that can work highly efficiently under the harsh reaction conditions,” said Yu.
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