Projects & Programs
Hydrogen Storage in Organic Clathrates
Well-known organic host molecules that sorb hydrogen at ambient conditions. Void space is shown as green and hydrogen molecules are shown as gray.
PNNL researchers Dr. Pete McGrail and Dr. Praveen Thallapally are working to meet the U.S. Department of Energy’s goals to store 15 weight percentage (wt%) of hydrogen at ambient conditions by 2010 using novel-host materials.
The impending energy crisis and related global pollution issues have inspired the investment of dedicated effort towards the discovery of new materials for gas storage and sequestration. Therefore, PNNL researchers are working on the design and construction of novel porous materials with large void spaces that can accommodate volatile molecular species (e.g., hydrogen gas). A significant target is the 15 wt% storage of hydrogen established by the U.S. Department of Energy for the development of hydrogen-fueled transportation by 2010, although these targets are slightly higher for the future. Thus, the development of a material that could store this amount of hydrogen at room temperature would no doubt generate enormous commercial and industrial interest.
The remarkable phenomenon of crystal porosity is attracting increasing attention, and PNNL researchers aim to describe this work in the context of other materials that are used for hydrogen storage. Experimental and theoretical work will be conducted to demonstrate the feasibility of storing hydrogen gas in novel organic solids governed by weak Van der Waal interactions.
One of the main research areas involves calix[n]arenes, macrocyclic molecules that are easily functional at either the upper or lower rim of the molecular skeleton. As a result of this process, conformational control over the skeleton can be achieved, although the cone conformation is common when the lower rim comprises hydroxyl functionality. While these molecules are used in various ways, PNNL researchers have found that the simple calix[4]arenes display the most remarkable properties in Van der Waals' crystals, which sorbs hydrogen gas at ambient conditions. Advantages of these materials, as compared to metal hydrides, include faster uptake and release of hydrogen at ambient conditions and easy regeneration of the host molecules. The host cavity can be fine-tuned to sorb additional amounts of hydrogen gas at ambient conditions using known synthetic routes.
PNNL researchers will consolidate their scientific findings and conclusions in quarterly reports to the client and in technical presentations and posters.
Products already produced include the following publications:
Thallapally, PK, GO Lloyd, TB Wirsiga, MW Bredenkamp, JL Atwood, and LJ Barbour. 2005. “Organic crystals absorb hydrogen gas under mild conditions.” The Royal Society of Chemistry: Chemical Communications: 5272-5274.
Thallapally, PK, Liliana Dobrza ska, TR Gingrich, TB Wirsig, LJ Barbour, and JL Atwood. 2006. "Acetylene absorption and binding in a nonporous crystal lattice.” Angewandte Chemie International Edition(45)39: 6506-6509.