Neutron Diffraction Studies of Hydrogen Adsorption in a Highly Stable Porous Rare-Earth Metal-Organic Framework

ORAL

Abstract

Gas sorption measurements show that a highly stable porous lanthanide metal-organic framework can take up hydrogen of about 2.1 wt. {\%} at 77 K and 10 bar. Difference Fourier analysis of neutron powder diffraction data revealed four distinct D$_{2}$ sites that are progressively filled within the nanoporous framework. Interestingly, the strongest adsorption sites identified are associated with the aromatic organic linkers rather than the open metal sites, as occurred in previously reported MOFs. Our results provide for the first time direct structural evidence demonstrating that optimal pore size (around 6 {\AA}, twice the kinetic diameter of hydrogen) strengthens the interactions between H$_{2}$ molecules and pore walls and increases the heat of adsorption, which thus allows for enhancing hydrogen adsorption from the interaction between hydrogen molecules with the pore walls rather than with the normally stronger adsorption sites (the open metal sites) within the framework. At high concentration H2-loadings (5.5 H2 molecules (3.7 wt. {\%}) per Y(BTC) formula), H2 molecules form highly symmetric novel nanoclusters with relatively short H2-H2 distances compared to solid H2. These observations are important and hold the key to optimizing this new class of rare metal-organic frameworks (RMOFs) materials for practical hydrogen storage applications.

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Authors

  • Junhua Luo

    Los Alamos National Laboratory

  • Shufang Su

    Iowa State University, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, University of Arizona, Sandia National Laboratories, Physics Department, Texas Tech University, Lubbock, TX 79409-1051, Northwestern University, Texas Tech University, University of Utah Department of Physics, University of Toulouse-UPS, IRSAMC, Toulouse, France, University of Arizona, Department of Physics, National Institute of Advanced Industrial Science and Technology, Texas A\&M University, Midwest Proton Radiotherapy Institute, Birdville ISD, Universidad de Colima, Universidad de Buenos Aires, Brigham Young University, UT Atlington, MV Systems, Colorado State University, St. Petersburg Electrotechnical University, New Mexico State University, Texas State Univ., CAMD/LSU, Texas Christian University, Fort Worth, TX, North Side High School, Fort Worth, TX, Nitronex Corporation, Arizona State University, Angelo State University Department of Physics, Texas Tech University Deptarment of Electrical Engineering

  • Shufang Su

    Iowa State University, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, University of Arizona, Sandia National Laboratories, Physics Department, Texas Tech University, Lubbock, TX 79409-1051, Northwestern University, Texas Tech University, University of Utah Department of Physics, University of Toulouse-UPS, IRSAMC, Toulouse, France, University of Arizona, Department of Physics, National Institute of Advanced Industrial Science and Technology, Texas A\&M University, Midwest Proton Radiotherapy Institute, Birdville ISD, Universidad de Colima, Universidad de Buenos Aires, Brigham Young University, UT Atlington, MV Systems, Colorado State University, St. Petersburg Electrotechnical University, New Mexico State University, Texas State Univ., CAMD/LSU, Texas Christian University, Fort Worth, TX, North Side High School, Fort Worth, TX, Nitronex Corporation, Arizona State University, Angelo State University Department of Physics, Texas Tech University Deptarment of Electrical Engineering

  • Shufang Su

    Iowa State University, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, University of Arizona, Sandia National Laboratories, Physics Department, Texas Tech University, Lubbock, TX 79409-1051, Northwestern University, Texas Tech University, University of Utah Department of Physics, University of Toulouse-UPS, IRSAMC, Toulouse, France, University of Arizona, Department of Physics, National Institute of Advanced Industrial Science and Technology, Texas A\&M University, Midwest Proton Radiotherapy Institute, Birdville ISD, Universidad de Colima, Universidad de Buenos Aires, Brigham Young University, UT Atlington, MV Systems, Colorado State University, St. Petersburg Electrotechnical University, New Mexico State University, Texas State Univ., CAMD/LSU, Texas Christian University, Fort Worth, TX, North Side High School, Fort Worth, TX, Nitronex Corporation, Arizona State University, Angelo State University Department of Physics, Texas Tech University Deptarment of Electrical Engineering