Transcript Slide 1

Hydrogen Storage
in Nano-Porous Materials
Dimitrios Argyris
The University of Oklahoma
School of Chemical, Biological, and Materials Engineering
Hydrogen Storage in Nano-Porous Materials
Introduction
Hydrogen storage
• 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
Fossil fuels
(biomass, hydro, wind, solar, and geothermal)
(coal ,natural gas, etc.)
Nuclear Energy
Hydrogen Storage in Nano-Porous Materials
Introduction
Hydrogen storage
• 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 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
Hydrogen Storage in Nano-Porous Materials
Storage Approaches
Porous Materials
• Single walled carbon nanotubes (CNT)
• Graphite materials
• Carbon nanofibers
High surface area sorbents
• 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
Hydrogen Storage in Nano-Porous Materials
Synthesis
Metal-Organic Frameworks
HKUST-1, Cu2(C9H3O6)4/3
• benzene-1,3,5-tricarboxylic acid
heated with
copper nitrate hemipentahydrate
O (red)
C (gray)
H (white)
Cu (purple)
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
HKUST-1*
*www.esrf.eu/
Hydrogen Storage in Nano-Porous Materials
Synthesis
Metal-Organic Frameworks
HKUST-1
MIL-101
Covalent-Organic Frameworks
COF-1
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
Hydrogen Storage in Nano-Porous Materials
Characterization
Infra-red spectra
Vibrational bands
1376 and 1340 cm-1→
B–O stretching
1023 cm-1 → B–C bonds
708 cm-1 → B3O3 ring units
Infra-red spectra of COF-1 (a)
Hydrogen Storage in Nano-Porous Materials
Characterization
Scanning Electron Microscopy
Particles Size
• COF-1: 0.3-0.4 μm
• HKUST-1: 4.0-8.0 μm
• MIL-101: 0.2-0.3 μm
COF-1 (a)
MIL-101 (c)
Unique morphology of particles
in each material
HKUST-1 (b)
Hydrogen Storage in Nano-Porous Materials
Characterization
BET surface area
BET surface area and pore volume → N2 adsorption at 77 K
BET surface area (m2/g)
• COF-1:
Pore volume (cm3/g)
628
0.36
• HKUST-1:
1296
0.69
• MIL-101:
2931
1.45
Hydrogen Storage in Nano-Porous Materials
Characterization
Hydrogen Adsorption
H2 Uptake (wt %)
H2 Uptake (wt %)
(77 K and 1 atm)
(298 K and 10 MPa)
• COF-1:
1.28
0.26
• HKUST-1:
2.28
0.35
• MIL-101:
1.91
0.51
Hydrogen Storage in Nano-Porous Materials
Characterization
Hydrogen Adsorption
MIL-101
Hydrogen adsorption at 298 K
MIL-101 - bridges - Pt/AC
Pt/AC and MIL-101 physical mixture (1:9 mass)
Pure MIL-101
Bridged spillover → hydrogen adsorption increased by a factor of 2.6 – 3.2
Hydrogen Storage in Nano-Porous Materials
Molecular Simulations
GCMC simulations → Predict adsorption isotherm for H2 →
10 isoreticular metal – organic frameworks (IRMOFs)
IRMOFs
Oxide - centered
Zn4O tetrahedra each
connected by six
dicarboxylate linkers†
3D cubic network
very high porosity
† variety of linkers can be used to get different pore sizes
Hydrogen Storage in Nano-Porous Materials
Molecular Simulations
Results
Low Pressure
High levels of adsorption
Narrow pores materials:
IRMOF-1, -4 , -6, -7
High Pressure
High levels of adsorption
Materials with
high free volume:
IRMOF-10, -16
Adsorption isotherms at 77 K
High uptake of H2
Low Pressure
High Pressure
Hydrogen Storage in Nano-Porous Materials
Molecular Simulations
Simulation Snapshots
Low pressure
(0.01 bar)
H2 near zinc corners
Intermediate pressure
(30 bar)
Molecules preferentially in
zinc corners and along linkers
High pressure
(120 bar)
H2 fills the majority of the
void regions of material
Hydrogen Storage in Nano-Porous Materials
Questions?