Hydrogen Storage for Mobile Applications. Jeff Van Humbeck MacMillan Group Meeting April 14 th, 2010

Transcription

1 ydrogen Storage for Mobile Applications Jeff Van umbeck MacMillan Group Meeting April 14 th, 2010

2 The Stone Age did not end for lack of stone, and the Oil Age will end long before the world runs out of oil. Sheikh Zaki Yamani (warning?) as Saudi OPEC Representative

3 Presentation Overview! 5 dominant absorptive materials that have been investigated widely CEMIABSORPTIVE MATERIALS PYSIABSORPTIVE MATERIALS Conventional hydrides Complex hydrides Metal-organic frameworks (MOFs) anostructured carbon (SWCTs) Chemicals hydrides (ammonia borane)! ot by any means comprehensive review of literature (1000s of papers since 2000)! For each material, attempt to highlight two main features: What are the comparative advantages/disavantages of particular technologies? What approach is current research taking to improve material characteristics?

4 Why Focus on Mobile Applications?! Stationary power storage can use technology where the volume and mass of storage don't matter

5 DOE ydrogen Storage Guidlines! In 2003 Department of Energy sets hydrogen storage goals Gravimetric Capacity Volumetric Capacity Operating Temperature/Pressure wt% 36 g/l wt% 45 g/l 30 to 50 ºC <100 bar wt% 81 g/l An onboard reversible system must have an endothermic hydrogen release Determined by!g!s > 60 J/K (T!S strongly favors release) Must be favored by!

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8 Conventional ydride Materials: Predictable Properties! Crystalline starting material and products make calculating properties simple Metal Alloy Conventional ydride Gravimetric Uptake (wt%) Lai 5 Lai FeTi FeTi Mg 2 i Mg 2 i ZrMn 2 ZrMn Mg Mg Principi, G.; Agresti, F.; Maddalena, A.; Lo Russo, S. Energy 2009, 34, 2087.! early demands the use of Mg (also, most cost effective)! What is limiting application of Mg 2 in hydrogen storage?

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10 Conventional ydride Materials: Uptake Kinetics! Unmodified Mg 2 requires high temperature for absorption/desorption Engineering solutions Ball milling: Reduce particle size, increase S.A. anoscale scaffold synthesis: O O O Porous Polymer Formation Mg 2 2 Form Mg 2 Zhang, S., et. al. anotechnology, 2009, 20,

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12 Conventional ydride Materials: Current State! Most important features: Operating parameters, storage capacity, refilling kinetics Mg wt% i Mg at% Mn Mg mol% Cr 2 O 3 Mg wt% b 2 O 5 Temp (ºC) Kinetics (min) Wt% # cycles 800 /A /A /A Reiser, A.; Bogdanovic, B.; Schlichte, K. Int. J. ydrogen Energy, 2000, 25, 425. Liang, G.; uot, J.; Boily, S.; estea, A. V.; Schulz, R. J. Alloys Compds. 1999, 292, 247. Dehouche, Z.; Klassen, T.; Oelerich, W.; Goyette, J.; Bose, T. K.; Schulz, R. J. Alloys Compds. 2002, 347, 319. Barkhordarian, G.; Klassten, T.; Bormann, R. J. Alloys Compds. 2004, 364, 242.

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14 Reversible ydrogen Uptake in Complex Metal ydrides! Similar strategy for improvement - transition metal dopant 3aAl 4 a 3 Al 6 + 2Al a 3 Al 6 3a + Al Dopants: Ti(OnBu) 4, TiCl 3, Zr(OiPr) 4, Ti(s)! Different advantages/disadvantages compared to conventional hydrides Advantages Disadvantages Lower operating temperature ( ) Kinetic charging/discharging (>60 min) Stability (<17 cycles) Sakintuna, B.; Lamari-Darkrim, F.; irscher, M. Int. J. ydrogen Energy 2007, 32, 1121.

15 Chemiabsorptive ydrogen Storage in Ammonia Borane! B/ Coordination compounds fall into 3 main classes - and B- bonds B-B and B- bonds B- bonds only 3 B 2 B B B B B B B 3 3 Likely to be explosive/shock-sensitive amilton, C. W.; Baker, T. R.; Staubitz, A.; Manners, I. Chem. Soc. Rev. 2009, 38, 279. Stephens, F..; Pons, V.; Baker, T. R. Dalton Trans. 2007, 2613.! Inherently more hydrogen rich than simplest complex hydride (19.6wt%)! Isoelectronic with alkanes, but far more reactive (protic and hydridic bonds)

16 Solvolytic ydrogen Release from Ammonia-Borane! Solvolytic hydrogen release is more viable than for ab 4 B +4 RO 3 2 [ 4 ][B(OR) 4 ] Catalyzed by: acid, heat, precious metals, base metals [ 4 ][B(OR) 4 ] LiAl 4 4 Cl Al(OR 3 ), 3 B 3, RO, 3, 2, LiCl Ramachandran, P. V.; Gagare, P. D. Inorg. Chem. 2007, 46, amilton, C. W.; Baker, T. R.; Staubitz, A.; Manners, I. Chem. Soc. Rev. 2009, 38, 279.! Requires an efficient conversion of Al(OMe) 3 to LiAl 4

17 Direct Dehydrogenation of Ammonia-Borane! Formation of B O bonds is energetic sink to be avoided B 2 B Catalyzed by: acid, base, precious metals, ligated base metals amilton, C. W.; Baker, T. R.; Staubitz, A.; Manners, I. Chem. Soc. Rev. 2009, 38, 279.! Mechanism for [Cp 2 Ti], (C) 2 i and (POCOP)Ir 2 are representative Ti Ph Ph Ph Ph i COD Ph Ph O P t Bu 2 Ir O P t Bu 2 Initial cleavage Initial B cleavage Concerted hydrogen transfer Luo, Y.; Ohno, K. Organometallics 2007, 26, Keaton, R. J.; Blacquiere, J. M.; Baker, T. R. J. Am. Chem. Soc. 2007, 129, Denney, M. C.; Pons, V.; ebden, T. J.; einekey, D. M.; Goldberg, K. I. J. Am. Chem. Soc. 2006, 128,

18 Ti-Catalyzed Dehydrogenation of Ammonia-Borane! Representative of initial bond cleavage Ti B Me Me Catalyst generated from TiCp 2 Cl 2 and nbuli in situ Ti Initial bond cleavage Ti B Me Me Iminoborane byproduct slowly dimerizes under reaction conditions B Me Me Ti Me Me Me Me B B Me Me B 3 Luo, Y.; Ohno, K. Organometallics 2007, 26, 3597.

19 i-catalyzed Dehydrogenation of Ammonia-Borane! Representative of initial B bond cleavage i Solv B ickel-c Catalyst i Initial B bond cleavage i B 2 3 Ph Ph Ph Iminoborane byproduct form borazine and higher polymers B B Me Me i B 2 B B B 3 Keaton, R. J.; Blacqueire, J. M.; Baker, T. R. J. Am. Chem. Soc. 2007, 129, 1844.

20 Ir-Catalyzed Dehydrogenation of Ammonia-Borane! Representative of concerted hydrogen generation O P t Bu 2 O Ir P t Bu 2 B Iridium-pincer complex based on alkane dehydrogenation catalyst O P t Bu 2 Ir O P t Bu 2 Concerted /B bond cleavage O P t Bu 2 O Ir P t Bu 2 B 2 3 Iminoborane byproduct slowly forms [ 2 B 2 ] 5 B O P t Bu 2 B 2 Ir 2 2 B 2 2 B 2 B 2 2 B 2 2 B 2 O P t Bu 2 Ankan, P.; Musgrave, C. B. Angew. Chem. Int. Ed. 2007, 46, Denney, M. C.; Pons, V.; ebden, T. J.; einekey, D. M.; Goldberg, K. I. J. Am. Chem. Soc. 2006, 128,

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22 Electronic Substitution of Ammonia-Borane! Stabilizing dative bond creates endothermic reaction F 3 C F 3 C 3 B 3 2 B 2 B B F 3 C F 3 C Electronic substitution does not stabilize true!-bond and dative "-bond as much as dative!-bond! Clear tradeoff with gravimetric capacity (< 1wt%) Staubitz, A.; Besora, M.; arvey, J..; Manners, I. Inorg. Chem. 2008, 47, 5910.

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31 Improving ydrogen Absorption Beyond Surface Area! Optimal binding energy can be calculated from first principles (thermodynamic strategy) For a system operating at RT, between 1.5 and 30 bar: 15.1 kj/mol! opt = T!S opt + RT ln P 1 P 2 2 P 0 2 For a system operating at RT, between 1.5 and 100 bar: 13.6 kj/mol For a typical MOF with! adb = 6 kj/mol Operating temperature: 131K (May be underestimated) Bhatia, S. K.; Myers, A. L. Langmuir 2006, 22, 1688.! Is there any way to kinetically improve the hydrogen storage properties? ysteresis

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34 Thermodynamic Strategies to Increase Binding Enthalpy! Increase interaction can be based on orbital or Coloumbic features M ipr 3 P CO W OC PiPr3 CO Filled d/empty! * Li + " " + Li + Kubas' Complex Orbital overlap Metal ion Coloumbic interaction Dipole/Induced dipole Up to 90 kj/mol M Up to ~24 kj/mol Empty p/filled! Kubas, G. J.; Ryan, R. R.; Swanson, B. I.; Vergamini, P. J.; Wasserman,. J. J. Am. Chem. Soc. 1984, 106, 451. Wu, C.. J. Chem. Phys. 1979, 71, 783.! These techniques have been applied (at least theoretically) to both MOFs and nanocarbons

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39 MOFs With Exposed Metal Sites! Metal impregnation on organic linkers provides another avenue O O O O O O 2 (atm) Cr CO 2 CO Cr(CO) 6, TF nbuo 2, 140 ºC Cr CO CO CO h! O O O O O O MOF-5 O O 2 (atm) Cr CO 2 CO O O Kaye, S. S.; Long, J. R. J. Am. Chem. Soc. 2008, 130, 806.

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