Flexible quantum sieve made at TU Dresden filters Starship Enterprise fuel – YubaNet



Deuterium, the heavy brother of hydrogen, is seen as a promising material for the future – due to its wide range of applications: in science, for energy generation or in the production of pharmaceuticals. However, extracting deuterium from its mixture of natural isotopes has so far been complex and expensive. With a porous material developed at the Technische Universität Dresden, this could soon be done more efficiently and cost-effectively. The new method has just been published in the scientific journal “Science Advances”.

Starship Enterprise flew across the galaxy using deuterium as fuel. Although this was science fiction of the 60s and 70s, research into the real-life application of the hydrogen isotope for power generation still continues today. The main challenge here is the extraction of the isotope. Deuterium (chemical abbreviation D, “heavy” hydrogen) is one of the three natural isotopes of hydrogen, along with protium (H, “normal” hydrogen) and tritium (T, “super heavy” hydrogen). Deuterium and protium are stable isotopes of hydrogen. Plain water and heavy water made from deuterium are also stable. Tritium (T) is extremely promising from a technical point of view, but it is not free from security problems due to its radioactivity.

Only deuterium can open the pores of DUT-8, while hydrogen leaves the frame closed. This highly selective detection leads to high separation selectivity combined with strong deuterium uptake. Copyright : Dr. Volodymyr Bon

Deuterium is extracted from heavy water, that is, water containing deuterium, which is contained at 0.15 per thousand in the natural water resources of our earth. To do this, heavy water is first isolated by chemical and physical processes, then deuterium gas is produced. These processes are so complex and energy-intensive that a gram of deuterium costs more than a gram of gold, even though its natural occurrence is several times higher.

But demand for pure deuterium continues to grow, as its unique physical properties mean that its potential applications are far from exhausted: when used in medicines, deuterium has already been shown to have a life-prolonging effect. life, although initially only for the active ingredient itself. Drugs containing deuterium can be dosed lower, so their side effects are also reduced. In nuclear reactors, deuterium plays an important role as a moderator. In addition, a mixture of deuterium and tritium or 3Helium should be used as fuel in future fusion reactors. Other areas of application include medicine, life sciences, analytics and new television displays.

In an interdisciplinary collaboration, the groups of Prof. Stefan Kaskel and Prof. Thomas Heine from TU Dresden, together with Dr. Michael Hirscher from MPI for Intelligent Systems Stuttgart, have now developed a new separation mechanism for isotopes of hydrogen based on the flexible metal-organic framework “DUT-8” developed at TU Dresden. “Our material makes it possible to separate deuterium gas from hydrogen. The unique DUT-8 metal-organic framework is very flexible and can dynamically adapt its pore size. But this structural response turned out to be highly selective: only deuterium can open the pores while hydrogen leaves the framework closed. This highly selective recognition leads to high separation selectivity combined with strong deuterium uptake,” says Stefan Kaskel, professor of inorganic chemistry at TU Dresden. With his group, he specializes in new nanostructured and porous functional materials for energy storage and conversion and has already developed several patented materials.

His DUT-8 material, published in 2012, initially showed no hydrogen absorption, either at high pressure or at very low temperatures. “During our measurements at the MPI in Stuttgart, we observed for the first time an opening of the DUT-8 structure under a deuterium atmosphere at very low temperature. Subsequently, we were also able to experimentally separate mixtures of hydrogen isotopes, with the material acting as a sort of flexible and therefore extremely efficient ‘quantum sieve'”, explains Dr Michael Hirscher, who has studied effective separation for hydrogen isotopes at MPI. for Intelligent Systems for several years.

First-principles calculations in conjunction with statistical thermodynamics predict the selective opening of isotopes and rationalize them with pronounced nuclear quantum effects. However, there are other so-called isotopologues (molecules of the same elements but different isotopes) of hydrogen, namely HD, HT, DT and T2, which must be taken into account in the separation, and those containing T are radioactive. In the group of Thomas Heine, Chair of Theoretical Chemistry at TU Dresden, the behavior of these isotopologues was simulated. “In this joint work, we succeeded in replacing problematic security-related experiments with radioactive materials with validated computer simulations and thus making predictions for potential applications of this isotope-dependent aperture effect of DUT-8. “, explains Professor Heine. His simulations show that DUT-8 opens only for isotopologues without light H isotopes. For HD, these predictions have already been confirmed experimentally by Dr. Hirscher’s group.

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