1. Hydrogen Storage in Nano-Porous Materials The University of Oklahoma School of Chemical, Biological, and Materials Engineering Dimitrios Argyris

2. Hydrogen Storage in Nano-Porous Materials Introduction Petroleum dependence → U.S. imports 55% of its oil expected to grow to 68% in 2025 Hydrogen as energy carrier → clean, efficient, and can be derived from domestic resources Renewable (biomass, hydro, wind, solar, and geothermal) Fossil fuels (coal,natural gas, etc.) Nuclear Energy Hydrogen storage

3. Hydrogen Storage in Nano-Porous Materials Introduction Hydrogen storage is a critical enabling technology for the acceptance of hydrogen powered vehicles Storing sufficient hydrogen on board to meet consumers requirements (eg. driving range, cost, safety, and performance) is a crucial technical parameter No approach currently exists that meets technical requir. driving range > 300 miles U.S. DoE → develop on board storage systems achieving 6 and 9 wt% for 2010 and 2015 Hydrogen storage

4. Hydrogen Storage in Nano-Porous Materials Storage Approaches Reversible on board Compressed hydrogen gas, Liquid hydrogen tanks, Metal hydrides, Porous materials Regenerable off-board Hydrolysis reactions, hydrogenation/dehydrogenation reactions, ammonia borane and other boron hydrides, alane (metal hydride), etc. Porous materials: usually carbon based materials with high surface area

5. Hydrogen Storage in Nano-Porous Materials Porous Materials High surface area sorbents Storage Approaches Single walled carbon nanotubes (CNT) Graphite materials Carbon nanofibers Metal-organic framework Theoretical studies: organometallic buckyball fullerenes, Si-C nanotubes Advantages: High surface area → fast hydrogen kinetics and low hydrogen binding energies → fewer thermal management issues

6. Hydrogen Storage in Nano-Porous Materials Synthesis Metal-Organic Frameworks HKUST-1 * * www.esrf.eu/ O (red) C (gray) H (white) Cu (purple) HKUST-1, Cu 2 (C 9 H 3 O 6 ) 4/3 benzene-1,3,5-tricarboxylic acid heated with copper nitrate hemipentahydrate in solvent consisting of equal parts of N,N-dimethylformamide (DMF), ethanol, and deionized water → filtration, drying, and solvent removal → porous material: HKUST-1 3 different metal organic frameworks

7. Hydrogen Storage in Nano-Porous Materials Synthesis Metal-Organic Frameworks HKUST-1 MIL-101 COF-1 Covalent-Organic Frameworks

8. Hydrogen Storage in Nano-Porous Materials Characterization X-ray diffraction X-ray diffraction patterns of (a) COF-1, HKUST-1, and (b) MIL-101. All samples show good crystallinity

9. Hydrogen Storage in Nano-Porous Materials Characterization Infra-red spectra Infra-red spectra of COF-1 (a) Vibrational bands 1376 and 1340 cm -1 → B–O stretching 1023 cm -1 → B–C bonds 708 cm -1 → B 3 O 3 ring units

10. MIL-101 (c) Hydrogen Storage in Nano-Porous Materials Characterization Scanning Electron Microscopy COF-1 (a) HKUST-1 (b) Unique morphology of particles in each material COF-1: 0.3-0.4 μm HKUST-1: 4.0-8.0 μm MIL-101: 0.2-0.3 μm Particles Size

11. Hydrogen Storage in Nano-Porous Materials Characterization BET surface area BET surface area and pore volume → N 2 adsorption at 77 K COF-1: 628 0.36 HKUST-1: 1296 0.69 MIL-101: 2931 1.45 BET surface area (m 2 /g)Pore volume (cm 3 /g)

12. Hydrogen Storage in Nano-Porous Materials Characterization Hydrogen Adsorption COF-1: 1.28 0.26 HKUST-1: 2.28 0.35 MIL-101: 1.91 0.51 H 2 Uptake (wt %) (77 K and 1 atm) H 2 Uptake (wt %) (298 K and 10 MPa)

13. Hydrogen Storage in Nano-Porous Materials Characterization Hydrogen Adsorption Hydrogen adsorption at 298 K MIL-101 Pure MIL-101 Pt/AC and MIL-101 physical mixture (1:9 mass) MIL-101 - bridges - Pt/AC Bridged spillover → hydrogen adsorption increased by a factor of 2.6 – 3.2

14. Hydrogen Storage in Nano-Porous Materials Molecular Simulations GCMC simulations → Predict adsorption isotherm for H 2 → 10 isoreticular metal – organic frameworks (IRMOFs) Oxide - centered Zn 4 O tetrahedra each connected by six dicarboxylate linkers † IRMOFs 3D cubic network very high porosity † variety of linkers can be used to get different pore sizes

15. Hydrogen Storage in Nano-Porous Materials Molecular Simulations Results Adsorption isotherms at 77 K IRMOF-1, -4, -6, -7 Low Pressure High Pressure IRMOF-10, -16 High Pressure Narrow pores materials: High levels of adsorption Materials with high free volume: High uptake of H 2

16. Hydrogen Storage in Nano-Porous Materials Molecular Simulations Simulation Snapshots Low pressure (0.01 bar) High pressure (120 bar) H 2 near zinc corners Molecules preferentially in zinc corners and along linkers Intermediate pressure (30 bar) H 2 fills the majority of the void regions of material

17. Hydrogen Storage in Nano-Porous Materials Questions?