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?