题目：Clathrate hydrates Science and Technology—Implication to the Future of Hydrogen Economy
演讲者：Dr. Yusheng Zhao
Staff Scientist, Los Alamos National Laboratory
1985 北京大学与 Berkerley大学交换学者
1986-1992 Stony Brook 大学博士
1992-1994 Caltech 大学博士后
1994-1996 Los Alamos 国家实验室博士后
1996-now Los Alamos国家实验室staff scientist
Recent discovery of hydrogen clathrate hydrates presents a completely new methodology for hydrogen storage and transportation. Ice-like polyhedral cage frameworks of clathrate hydrates can hold substantial amounts of molecular hydrogen by taking advantage of the ability of multiple H2 molecules to occupy a single clathrate cage. Unusually strong intermolecular interactions result in high density of H2 localized in these nanoscale cages, yielding high H2 density up to 5.23% of total mass under moderate pressure (1 kbar), and low-temperatures (160 K). This content is notably higher than the current state-of-the-art hydrogen-storage metal hydrides. In terms of volume capacity, the H2 clathrate hydrate can hold up to 20 moles per liter, approaching that of liquid hydrogen (~ 35 moles per liter, @ T=20 K & P=1 bar).
Our recent neutron diffraction studies reveal that hydrogen clathrate hydrate has a great capability to reversibly entrap and/or release substantial amounts of molecular hydrogen. We have also developed a clathrate synthesis technique to rapidly form hydrogen hydrate to its full storage capacity in just a matter of minutes, greatly extending its feasibility for large-scale production. Another obvious advantage of H2 clathrate as the hydrogen storage medium is that, unlike the metal hydrides with limited life cycles, clathrate hydrates can be recharged indefinitely and are virtually inexhaustible. High-energy content, fast kinetics, easy reversibility, and vast resources are advantages that make hydrogen clathrate an excellent candidate material for hydrogen storage.
The clathrate hydrate science and technology study addresses global energy and environmental issues. We propose to inject carbon dioxides into the methane clathrate deposits at the ocean floor. It will sequester CO2 in clathrate hydrates while harvesting CH4 fuel, a fascinating kill-two-birds-with-one-stone solution. Our study on the relationships of crystal structure, thermodynamic stability, controlled kinetics, for hydrogen clathrate can provide a deep understanding of hydrogen bonds, guest-host interaction, and insertion and release mechanisms of gas molecules in clathrate hydrates. The proposed systematic study on hydrogen hydrates will clarify and identify the possibilities and limitations for application of these materials in hydrogen storage. The scientific and technological achievements of this research project are expected to have profound impacts on the fundamental natures of the clathrate hydrates, which are important to a wide range of scientific and technological communities.