To make natural gas and biogas suitable for use, the methane has to be separated from the CO2. This involves the use of membranes: filters that stop the methane and let the CO2 pass through. Researchers at KU Leuven (University of Leuven), Belgium, have developed a new membrane that makes the separation process much more effective.
When it comes to extracting natural gas or producing biogas, it's all about the methane. But methane is never found in its pure form. Natural gas, for instance, always contains quite a bit of carbon dioxide (the greenhouse gas CO2), sometimes up to 50 percent.
Natural gas or biogas always needs to be purified before use. First, the methane molecules (in black and white) are separated from the CO2 molecules (in red and black) by means of membranes with tiny pores through which only the CO2 can pass. After the purification process, the methane can be used as fuel, for heating, or for the production of chemicals.
Credit: KU Leuven - Verbeke
To purify the methane - or, in other words, remove the CO2 - the industry often uses membranes. These membranes function as molecular sieves that separate the methane and the CO2. The methane can then be used as a source of energy for heating, for the production of chemicals, or as fuel, while the CO2 can be reused as a building block for renewable fuels and chemicals.
Existing membranes still need to be improved for effective CO2 separations, says Professor Ivo Vankelecom from the KU Leuven Faculty of Bioscience Engineering. "An effective membrane only allows the CO2 to pass through, and as much of it as possible.
The commercially available membranes come with a trade-off between selectivity and permeability: they are either highly selective or highly permeable. Another important problem is the fact that the membranes plasticise if the gas mixture contains too much CO2. This makes them less efficient: almost everything can pass through them, so that the separation of methane and CO2 fails."
The best available membranes consist of a polymeric matrix with a filler in it, for instance a metal-organic framework (MOF). This MOF filler has nanoscale pores. The new study has shown that the characteristics of such a membrane improve significantly with a heat treatment above 160 degrees Celsius during the production process.
"You get more crosslinks in the polymeric matrix: the net densifies, so to speak, and that in itself already improves the membrane performance, because it can no longer plasticise. At these temperatures, the structure of the MOF - the filler - changes, and it becomes more selective. Finally, the high-temperature treatment also improves polymer-filler adhesion: the gas mixture can no longer escape through little holes at the filler-polymer interface." This gives the new membrane the highest selectivity ever reported, while preventing plasticisation when the concentration of CO2 is high. "If you start off with a 50/50 CO2/methane mixture, this membrane gives you 164 times more CO2 than methane after permeation through the membrane," Dr Lik Hong Wee explains. "These are the best results ever reported in scientific literature." This study is a collaboration between KU Leuven (Professor Ivo Vankelecom and Dr Lik Hong Wee from the Faculty of Bioscience Engineering / Centre for Surface Chemistry and Catalysis) and UAntwerp (EMAT unit led by Professor Sara Bals). Project website: http://www.
Professor Ivo Vankelecom
Professor Ivo Vankelecom | EurekAlert!
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Separate brain systems cooperate during learning, study finds
22.02.2018 | Brown University
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
22.02.2018 | Life Sciences
22.02.2018 | Physics and Astronomy
22.02.2018 | Earth Sciences