Zeolite Framework Materials for Hydrogen Storage Paul Anderson School of Chemistry The University of Birmingham
Zeolites aluminosilicates composed of cornersharing TO 4 tetrahedra Key: Silicon/ Aluminium Oxygen 4-ring (S4R) 6-ring (S6R)
Zeolites aluminosilicates composed of cornersharing TO 4 tetrahedra sodalite cage (β-cage)
Zeolites aluminosilicates composed of cornersharing TO 4 tetrahedra now possible to incorporate over one third of the elements of the periodic table into zeolite-like frameworks Sodalite (SOD structure type) Zeolite A (LTA) Zeolites X & Y (FAU)
Exchangeable cations general formula: Mx/n [(AlO2)x (SiO2)y].m H2O + = sodium zeolite A (Na-A) Zeolite Framework Materials for Hydrogen Storage Paul Anderson, H2
Zeolite uses Zeolites have found many important industrial uses including: Shape and size selective catalysis Cracking of hydrocarbons Ion exchange Zeolites have also been used in double glazing animal feed - pigs, hens and humans (coffee mate) also being marketed as alcohol adsorbents, foot odour destroyers and cat litter. Zeolite Framework Materials for Hydrogen Storage
Why zeolites for hydrogen storage? specific surface area up to 910m 2 g -1 crystalline solids well defined pores well defined adsorption sites ease of characterization ease of chemical modification low cost chemical stability not flammable in air not flammable in hydrogen Zeolite Framework Materials for Hydrogen Storage
Previous work on hydrogen in zeolites three temperature regimes low temperature 1.2 wt% for Na-X at 77K, 0.6 bar [Kazansky et al. Microporous and Mesoporous Materials 22, 251-259 (1998).] room temperature 1.2 wt% for Na-A at 700 bar [Darkrim et al. Journal of Chemical Physics 112 (13), 5991-5999 (2000).] high temperature 0.6 wt % for Cs-A at 300 C, 917 bar [Fraenkel & Shabtai, Journal of the American Chemical Society 99, 7074-7076 (1977).] Zeolite Framework Materials for Hydrogen Storage
Systematic study four different zeolites: X, Y, A & Rho three different structure types: FAU, LTA & RHO three different Si/Al ratios: ~1, 2.4, 3.0 77K The Periodic Table of the Elements Zeolite Framework Materials for Hydrogen Storage
Zeolite X FAU structure type Si/Al = 1.2 Zeolite Framework Materials for Hydrogen Storage
Zeolite X 2.5 Hydrogen adsorption (wt.%) 2 1.5 1 0.5 0 0 2 4 6 8 10 12 14 16 LiX ad s o rp t io n LiX desorption MgX adsorption MgX desorption AgX adsorption AgX desorption KX ad s o rp t io n KX d es o rp t io n Pressure (bar)
Zeolite X 2.5 Hydrogen adsorption (wt.%) 2 1.5 1 0.5 R 2 = 0.8 AgX NiX SrX RbX CdX CsX CaX KX NaX MgX CoX ZnX LiX 0 0 100 200 300 400 500 600 700 800 BET surface area (m 2 /g)
Zeolite Y also FAU structure type Si/Al = 2.4 33% fewer cations Zeolite Framework Materials for Hydrogen Storage
Zeolite Y 2 Hydrogen adsorption (wt.%) 1.6 1.2 0.8 0.4 LiY KY CsY NaY RbY 0 0 2 4 6 8 10 12 14 16 Pressure (bar) Zeolite Framework Materials for Hydrogen Storage
Zeolite Y 2.4 Hydrogen adsorption (wt.%) 2 1.6 1.2 0.8 0.4 R 2 = 0.7953 CsY CrY BaY AgY MgY SrY NiY KY CaY NaY RbY ZnY CoY CuY CdY LiY 0 0 100 200 300 400 500 600 700 800 BET surface area (m 2 /g)
Zeolites X & Y Cation Expected H 2 uptake (± 0.05 wt.%) X Expected H 2 uptake (± 0.05 wt.%) Li + 1.99 1.94 Na + 1.79 1.81 K + 1.63 1.69 Rb + 1.43 1.51 Cs + 1.22 1.32 Mg 2+ 1.89 1.85 Ca 2+ 1.82 1.83 Sr 2+ 1.58 1.68 Co 2+ 1.73 1.77 Ni 2+ 1.74 1.78 Zn 2+ 1.76 1.80 Ag + 1.19 1.39 Cd 2+ 1.47 1.58 Y
Zeolites X & Y Cation Expected H 2 uptake (± 0.05 wt.%) X Observed H 2 uptake (± 0.05 wt.%) Expected H 2 uptake (± 0.05 wt.%) Y Observed H 2 uptake (± 0.05 wt.%) Li + 1.99 2.17 1.94 1.80 Na + 1.79 1.79 1.81 1.81 K + 1.63 1.96 1.69 1.87 Rb + 1.43 1.46 1.51 1.48 Cs + 1.22 1.32 1.32 1.33 Mg 2+ 1.89 1.62 1.85 1.76 Ca 2+ 1.82 2.19 1.83 1.82 Sr 2+ 1.58 1.68 1.68 1.59 Co 2+ 1.73 1.42 1.77 1.52 Ni 2+ 1.74 1.64 1.78 1.46 Zn 2+ 1.76 1.63 1.80 1.46 Ag + 1.19 1.27 1.39 1.34 Cd 2+ 1.47 1.42 1.58 1.47
Zeolites X & Y H 2 uptake (± 0.05 wt.%) H 2 uptake (molecules/unit cell) Cation X Y X Y Li + 2.17 1.80 130 106 Na + 1.79 1.81 120 114 K + 1.96 1.87 144 126 Rb + 1.46 1.48 122 113 Cs + 1.32 1.33 129 116 Mg 2+ 1.62 1.76 102 107 Ca 2+ 2.19 1.82 143 114 Sr 2+ 1.68 1.59 127 109 Co 2+ 1.42 1.52 98 98 Ni 2+ 1.64 1.46 113 94 Zn 2+ 1.63 1.46 110 93 Ag + 1.27 1.34 127 110 Cd 2+ 1.42 1.47 115 106
Zeolite A LTA structure type Si/Al = 1.0 Zeolite Framework Materials for Hydrogen Storage
Zeolite A Hydrogen adsorption (wt.%) 2 1.5 1 0.5 0 0 2 4 6 8 10 12 14 16 MgA a dsorprt ion MgA desorption ZnA a dsorpt ion ZnA de sorpt ion CoA adsorption CoA desorption CaA adsorption CaA desorption Pressure (bar)
Zeolite A 2 Hydrogen adsorption (wt.%) 1.6 1.2 0.8 0.4 0 LiA NaA KA RbA CsA 0 2 4 6 8 10 12 14 16 Pressure (bar)
Zeolite A 1.8 Hydrogen adsorption (wt.%) 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0% 9.4% 11.5% 12.5% 14.6% 0 0 2 4 6 8 10 12 14 16 Pressure (bar)
Zeolite A Hydrogen adsorption (wt.%) 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 AgA NaA HA R 2 = 0.9372 LiA KA RbA CsA CdA SrA NiA MgA CoA CaA ZnA 0 100 200 300 400 500 600 BET surface area (m 2 /g)
Zeolite Rho RHO structure type Si/Al = 3.0 Zeolite Framework Materials for Hydrogen Storage
Zeolite Rho Hydrogen adsorption (wt.%) 1.2 1 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12 14 16 CoRho NiRho CuRho ZnRho AgRho CdRho (2) CdRho (1) NaCsRho Pressure (bar)
Zeolite Rho 2 Hydrogen adsorption (wt.%) 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 ZnRho CuRho CoRho BaRho HRho NiRho AgRho LiRho CdRho (2) NaRho NaCsRho KRho RbRho CaRho SrRho CdRho (1) MgRho 0 100 200 300 400 500 BET surface area (m 2 /g)
Langmuir model p n = 1 n b + p m n m n is the specific amount of gas adsorbed at equilibrium pressure p n m is the monolayer capacity b is the adsorption coefficient Pressure / weight percent H 2 (bar/wt.%) 25 20 15 10 5 0 BaRho (R-squared =0.9995) MgRho (R-squared = 0.9997) NiRho (R-squared = 0.9997) HRho (R-squared = 0.9997) 0 2 4 6 8 10 12 14 16 Pressure (bar)
Langmuir model Zeolite Measured H 2 uptake (± 0.05 wt.%) n m (± 0.01 wt.%) b (bar -1 ) LiX 2.17 2.27 1.39 ± 0.05 NaX 1.79 1.84 3.64 ± 0.38 CaX 2.19 2.34 0.86 ± 0.04 CoX 1.42 1.49 1.56 ± 0.07 ZnX 1.63 1.79 0.58 ± 0.02 KY 1.87 1.94 2.94 ± 0.26 RbY 1.48 1.53 2.19 ± 0.09 SrY 1.59 1.72 0.92 ± 0.08 NiY 1.46 1.56 1.08 ± 0.04 NaA 1.54 1.57 3.03 ± 0.15 CaA 1.89 1.94 2.63 ± 0.10 CoA 1.27 1.31 3.28 ± 0.05 AgA 1.63 1.67 2.40 ± 0.23 CdA 1.09 1.18 5.34 ± 0.20 MgRho 1.75 1.81 1.63 ± 0.09 NiRho 0.64 0.68 1.15 ± 0.05 HRho 1.73 1.79 1.54 ± 0.09
Langmuir model SA LAN = nm N Aσ RMM n m is the monolayer capacity N A is Avogadro s number σ is the area occupied by a hydrogen molecule on the surface RMM is the relative molecular mass of hydrogen (H 2 ) Zeolite SA LAN from H 2 uptake (m 2 /g) SA BET from N 2 uptake (m 2 /g) LiX 832 742 NaX 647 662 CaX 858 669 CoX 550 554 ZnX 660 571 KY 711 655 RbY 560 551 SrY 627 604 NiY 572 556 NaA 576 CaA 711 565 CoA 480 454 AgA 612 CdA 433 353 MgRho 663 383 NiRho 249 7 HRho 656 22
Comparison with activated carbons 5 4.5 Hydrogen adsorption (wt.%) 4 3.5 3 2.5 2 1.5 1 0.5 Zeolite X Zeolite Y Zeolite A Zeolite Rho Carbo n materials 0 0 500 1000 1500 2000 BET surface area (m 2 /g) Zeolite Framework Materials for Hydrogen Storage
Comparison with activated carbons 4 wt.% H 2 per 1000 m 2 /g material 3.5 3 2.5 2 1.5 1 0.5 0
Comparison with activated carbons 35 Volumetric hydrogen storage capacity (kgh 2 /m 3 ) 30 25 20 15 10 5 0
Possible advantages of zeolites in stationary hydrogen stores low cost lower gravimetric but higher volumetric capacity than carbon not flammable in air or in H 2 chemically tunable to trap hydrogen at room temperature and above?
Acknowledgments EU FP5 FUCHSIA Project The Carbon Trust EPSRC UK SHEC Henrietta Langmi Ian Gameson, Rex Harris, John Speight, David Book, Allan Walton, Malek Al-Mamouri Peter Edwards