Numerical study of new porous open carbon
frameworks (OCF) for hydrogen storage
Bogdan Kuchta
Hydrogen storage
Hydrogen storage
Hydrogen storage
Hydrogen storage
”Magic numbers” for: 2010 2017 Ultimate
Energetic capacity(kWh kg −1) (specific energy) 1.5 1.8 2.5
Gravimetric capacity(g H2 / kg) 45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)
Volumetric capacity (energy density) (kWh l −1) 0.9 1.3 2.3
Volumetric capacity(g H2 / l) 28 40 70
DOE targets for hydrogen storage system
DOE targets for hydrogen storage system
45
55
75
Gravimetric capacity[g H2 / kg]
2840
70
Volumetric capacity[g H2 / l]
ultimate
2017
2010
2331
71
H2, gas(350bar, 298K)
H2, gas(700bar, 298K)
H2, liquid(1bar, 20K)
in g/L
Compression and liquefaction
Storage by physisorption: Classical storage:
Outline:
1. Where is the problem …
2. Pure carbon: a multilayer adsorption ?
3. Chemically modified graphene: higher energy of adsorption and heterogeneity
4. Modification of the structure: higher specific area
What are the physical limits required to achieve the DOE goals?
Graphene slit (surface area ~2600 m2/g)
Adsorbent model – local slits
H2H2H2 H2
D6-40 Ǻ
Carbon – based adsorbent with
local
graphene – like structure
−
=−
4102
5
22)(
2 zzzV grapheneH
σσσσσσσσεεεεπρσπρσπρσπρσ
−
=−
612
4)(22 rr
rV HH
σσσσσσσσεεεε
εεεε σσσσH2-H2 34.2 2.96
H2-C 45.1 2.89
Potential parameters
H2-H2 interaction
Interaction models – pristine graphene
H2-graphene interaction
H2
H2
Molecular H2
Super-atom H2
Radius = σσσσH2
Super-atom model
H2 – H2
H2 – graphene wall
Interaction models – pristine graphene
2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
Ene
rgy
(K)
r (A)
classic T=77 T=50
H2-H
2 (from Matera)
with quantum corrections
2 3 4 5 6-600
-500
-400
-300
-200
-100
0
H2- graphene (from Matera)
with quantum corrections
Ene
rgy
(K)
z(A)
classic T77 T50
= 5.6 wt%
= 8 wt%
= 107 wt%
Limits of adsorption on graphitic surfaces
45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)
Hydrogen adsorption in pores
H2
0 1 2 3 4 5 6 7 8 9 100
2000
4000
6000
Dis
trib
utio
n
Z (A)
d = 1.08 nm
0 20 40 60 80 100 1200
1
2
3
4
5
6
7
8
9
10
11
T=298Ktotal
total
excess
wei
gth%
P (bar)
T=77K
excess
The colors of the isotherms correspond to the colors of the distributions (T = 77 K)
Isotherms (pristine +15kJ)
0 20 40 60 80 100 1200
2
4
6
8
10
12
14
T = 77 K
wei
ght%
P (bar)
T = 298 K
0 1 2 3 4 5 6 7 8 9 100
2000
4000
6000
8000
10000
12000
14000
16000
T = 77 KE = 4.5 kJ
Dis
trib
utio
n
Z (A)
0 1 2 3 4 5 6 7 8 9 100
2000
4000
6000
8000
10000
12000
14000
16000
Dis
trib
utio
n
Z (A)
T = 77 KE = 15 kJ
The colors of the isotherms correspond to the colors of the distributions (T = 77 K)
Isotherms (pristine +15kJ)
0 20 40 60 80 100 1200
2
4
6
8
10
12
14
T = 77 K
wei
ght%
P (bar)
T = 298 K
0 1 2 3 4 5 6 7 8 9 100
2000
4000
6000
8000
10000
12000
14000
16000
T = 77 KE = 4.5 kJ
Dis
trib
utio
n
Z (A)
0 1 2 3 4 5 6 7 8 9 100
2000
4000
6000
8000
10000
12000
14000
16000
T = 298 KE = 15 kJ
Dis
trib
utio
n
Z (A)
Adsorption (D=5-15 A)
0 2 4 6 8 1 0 1 2 1 4- 6 0 0
- 5 0 0
- 4 0 0
- 3 0 0
- 2 0 0
- 1 0 0
0
D = 1 5 Å
Ene
rgy
(K)
z ( Å )
0 1 2 3 4 5 6 7 8 9 10-600
-500
-400
-300
-200
-100
0
D = 10 Å
d)
Ene
rgy
(K)
z (Å)
0 1 2 3 4 5 6 7-800
-700
-600
-500
-400
-300
-200
-100
0
Ene
rgy
(K)
z (Å)
D = 7 Å
0 2 4 6-1100
-1000
-900
-800
-700
-600
-500
-400
-300
-200
-100
0
D = 6 Å E
nerg
y (K
)
Z (A)
6 8 10 12 14-1200
-1000
-800
-600
-400
-200
0
Ene
rgy
(K)
Slit width (Å )
Emin
Emid
a)
Adsorption – multilayer formation
T = 298 K
T = 77 K
Adsorption – multilayer formation
d = 1.5 nm
6 8 10 12 140
2
4
6
8
10
12
14
16
T = 77 KE = 15 kJ/mol
wei
ght
%
pore width [إ]
6 8 10 12 140
2
4
6
8
10
T = 298 KE = 4.5 kJ/mol
wei
ght %
6 8 10 12 140
2
4
6
8
10
T = 298 KE = 15 kJ/mol
wei
gth
%DOE 2010DOE 2015
77 K
298 K
E = 4.5 kJ/molkJ/molkJ/molkJ/mol E = 15 kJ/mol
DOE 2010DOE 2015
6 8 10 12 140
2
4
6
8
10
12
14
16
wei
ght %
pore width (Å)
T = 77 KE = 4.5 kJ/mol
Adsorption limits: pore width 5 - 15 Å
ultimate
ultimate
45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)B. Kuchta, L. Firlej, P. Pfeifer and C. Wexler, Carbon 48, 223 –231(2010)
Outline:
1. Where is the problem
2. Pure carbon: a multilayer adsorption ? NO !!!
3. Chemically modified graphene: higher energy of adsorption and heterogeneity
4. Modification of the structure: higher specific area
What are the physical limits to get the DOE goals?
6 8 10 12 140
2
4
6
8
10
12
14
16
T = 77 KE = 15 kJ/mol
wei
ght
%
pore width [إ]
6 8 10 12 140
2
4
6
8
10
T = 298 KE = 4.5 kJ/mol
wei
ght %
6 8 10 12 140
2
4
6
8
10
T = 298 KE = 15 kJ/mol
wei
gth
%DOE 2010DOE 2015
77 K
298 K
E = 4.5 kJ/molkJ/molkJ/molkJ/mol E = 15 kJ/mol
DOE 2010DOE 2015
6 8 10 12 140
2
4
6
8
10
12
14
16
wei
ght %
pore width (Å)
T = 77 KE = 4.5 kJ/mol
Adsorption limits: pore width 5 - 15 Å
ultimate
ultimate
45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)B. Kuchta, L. Firlej, P. Pfeifer and C. Wexler, Carbon 48, 223 –231(2010)
Quantitative changes: ab initio calculations
Graphene ���� Ea= 5.16 kJ/mol
Graphene - B ���� Ea= 7.8 kJ/mol
Ea= 5.56 kJ/mol
Minimal energies
Energy over carbonbonded to boron
1 kJ/mol=120 K
Flat configuration: extended Ea model
-20 -10 0 10 20
-900
-800
-700
-600
3.10
3.15
3.20
3.25
3.30
3.35
3.40
3.45
distance [Å]
energy [K]
distance from surface [Å]
E(min) = -936 KE(max) = -583 KE(aver) = -605K
1 kJ/mol=120 K
E(min) = -938 KE(max) = -583 KE(aver) = -654 K
E(min) = -1050 KE(max) = -596 KE(aver) = -746 K
E(min) = -1156 KE(max) = -630 KE(aver) = -897 K
E(min) = -1523 KE(max) = -897 KE(aver) = -1152 K
Random boron substitution: 1% - 10%
1% 2.5% 5% 10%1% 2.5% 5% 10%1% 2.5% 5% 10%1% 2.5% 5% 10%1% 2.5% 5% 10%1% 2.5% 5% 10%1% 2.5% 5% 10%1% 2.5% 5% 10%
∆E = 350 K ∆E = 450 K ∆E = 530 K ∆E = 630 K∆E = 350 K ∆E = 450 K ∆E = 530 K ∆E = 630 K
1 kJ/mol=120 K
Random substitution : 10% C substituted
MC simulation
Ab initioE = 7.5 – 12.5 kJ/mol
L. Firlej, Sz. Roszak, B. Kuchta, P. Pfeifer and C. Wexler, J. Chem. Phys. 131, 164702 (2009)
Outline:
1. Where is the problem
2. Pure carbon: a multilayer adsorption ? NO !!!
3. Chemically modified graphene: higher energy of adsorption and heterogeneity YES but not ultimate
4. Modification of the structure: higher specific area
What are the physical limits to get the DOE goals?
Search for higher surface ….
FROM: Nature 427, 523-527 (2004)
a) A graphene sheet extracted from the
graphite structure has a surface area of
2,620 m2 g-1 - the best activated carbons !!
b) A series of poly-p-linked six-member rings can
be extracted from that sheet, thus increasing
the surface area to ~5,680 m2 g-1.
c)Excision of six-member rings 1,3,5-linked to a
central ring raises the surface area to
~6,200 m2 g-1.
d)The surface area reaches a maximum of
~7,750 m2 g-1 when the graphene sheet is
fully decomposed into isolated six-member
rings.
Carbon adsorbent hypothetical models
The model of Kaneko ( 1992)
Mol Nb of C size(nm) Surface(m2g-1)
A 56 1.1x2.1 5800B 71 1.5x2.1 6000C 110 1.5x2.6 4700D 158 1.5x3.5 4400E 212 1.9x3.5 4100
the polyphenylene model Gibson et al. ( 1946) and Riley ( 1947)
SCIENCE VOL 295 18 JANUARY 2002
MOF, COF, PAF, …
Angew. Chem. Int. Ed. 2009, 48, 4730 –4733
MOF COF PAF
Phys Chem Lett. 2010, 1, 978-981
MOF, COF, PAF comparison with graphene…
45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)
J.Lan et al., Phys.Chem.Lett 1,978 (2010)
PAF-302 Surface (m2/g): 7100 2600
Adsorption (g H2/kg) :
T = 77 K : 115 95
T = 298 K : 25 20Energy of Adsorption: <4.6 kJ/mol 4.5 kJ/mol
Density (g/cm3): 0.32 0.76
MOF, COF, PAF – edge energetic effect
0 2 4 6 8 10 12 14 16 18
-60
-50
-40
-30
-20
-10
0
edge
center
Ene
rgy
(meV
)
Site
>30%
Competition between increasing surface and weaker energy
1 kJ/mol=120 K
Policyclic Aromatic Hydrocarbons (PAH)
ovalene
pyrene
coronene
corannulene
-20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
-10
0
10
+ + =
Improved adsorbent (Open Framework Carbon)
-10 0 10 20 30 40
-10
0
10
20
30
40Y
(A
)
X (A)
-40 -30 -20 -10 0 10 20 30 40
-40
-30
-20
-10
0
10
20
30
40
Y (
A)
X (A)
-80 -60 -40 -20 0 20 40 60-80
-60
-40
-20
0
20
40
60
Y (
A)
X (A)
-40 -30 -20 -10 0 10
-10
0
10
20
30
40
Y (
A)
X (A)
3D-Patch 3D-Ortho
B. Kuchta, L. Firlej, A. Mohammadhosseini, M. Beckner, J. Romanos, and P.Pfeifer,
Journal American Chemical Soc, 134, 15130−15137(2012)
0 20 40 60 80 1000
30
60
90
120
150
180
210
240
270
Tot
al (
g/kg
)
pressure (bar)
3D Patch 3D Cubic
0 20 40 60 80 1000
20
40
60
80
100
Exc
ess
(g/k
g)
pressure (bar)
0 20 40 60 80 1000
20
40
60
Tot
al (
g/kg
)
pressure (bar)
3D Patch 3D Cubic
3D-Ortho3D-Patch
Graphene
Open symbols – energy of adsorption doubled
45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)
T = 300 K
T = 77 K
PAF
Improved adsorbent (Open Framework Carbon)
45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)
Improved adsorbent (Open Framework Carbon)
MOF, COF, PAF comparison with OCF
45 (4.5 wt%) 55 (5.5 wt%) 75 (7.5 wt%)
PAF-302 PAF-303 3D-Patch 3D-Ortho Cor_BenzSurface (m2/g): 7100 …… 2600 3500 4200 6500
Adsorption (g H2/kg) :
T = 77 K : 115 170 95 120 265 131
T = 298 K : 25 40 20 17 48 25Energy of Adsorption: <4.6 kJ/mol 4.5 kJ/mol <4.5 kJ/mol <4.5 kJ/mol
Density (g/cm3): 0.32 0.16 0.76 0.48 0.16 0.40
J.Lan et al., Phys.Chem.Lett 1,978 (2010)
Outline:
1. Where is the problem
2. Pure carbon: a multilayer adsorption ? NO !!!
3. Chemically modified graphene: higher energy of adsorption and heterogeneity YES but not ultimate
4. Modification of the structure: higher specific area Yes but combined with higher energy
What are the physical limits to get the DOE goals?
0 2000 4000 6000 8000 10000 12000 140000
2
4
6
8
10
12
14
16
18
20
Ene
rgy
of a
dsor
ptio
n (k
J/m
ol)
Surface (m2)
- at T = 300K, p=100 bar , for Ea = 4.5 kJ/mol,carbons storage capacity is not higher than 7.5 gH2 per kg and per 1000 m 2 of surface.
- the density of adsorbed molecules (at RT) increases ~ linearly with E a up to 15 kJ/mol
Cm (100 bar) = (1.5/1000)*S*E a
general formula to estimate gravimetric storage capacity C m :
90 75 50252015
existing carbons
boron-dopedmodel reasonable
goal?
(in g/kg)
(DOE ultimate)
What would be a reasonable goal:
Conclusion:
1. New light porous materials with high specific surfaces (> 5000 m2/g)
and larger energy of adsorption (>10 kJ/mol) must be defined and synthesized.
2. Open architecture based on graphene fragments is important!(to take an advantage of the additional edge surfac e).
3. The size of graphene fragments should be optimized (cannot be to small because it leads to lower energy of adsorption and decreasing uptake).
4. Is it possible to synthesize proposed structure s?