提高氨硼烷儲氫性能

1、Reporter: Guanglin Xia Members: Zhenjie Wang Zhicheng Liu Liangliang Zou Yanan Kang Yuan LiImproved Hydrogen Storage Properties of Ammonia BoraneContentsIntroductionNanoscaffold MediationSubstituting H atom in the NH3 group23 It has become increasingly clear that hydrogen as an energy carrier is in

2、and carbonaceous fuels are out. Hydrogen energy is high efficiency and near zero emissions. The hydrogen economy is coming.James A. Ritter, Materialstoday, September 200345H2 storage is a critical enabling technology for H2 use as an energy carrierThe low volumetric density of gaseous fuels requires

3、 a storage method which compacts the fuel. Hence, hydrogen storage systems are inherently more complex than liquid fuels.Storage technologies are needed in all aspects of hydrogen ductiondistributionutilization678Ammonia borane (AB), NH3BH3, has been considered as a promising candidat

4、e material for hydrogen storage due to its very large stoichiometric hydrogen content (19.6 wt %), moderate temperatures(about 120 oC) for thermal decomposition, the exothermic nature of decomposition process, as well as the fact that it is inflammable and nonexplosive.910Reactions (1) and (2) stepw

5、ise releases 6.5 and 6.9 wt % of hydrogen below 200 oC, with the formation of polyaminobrane (NH2BH2)x and polyiminoborane (NHBH)x, respectively. Reaction (3) releases 7.3 wt % of hydrogen, but is impractical for hydrogen storage because of the very high decomposition temperature (500 oC). During th

6、e thermal decomposition process, besides hydrogen, highly volatile products, involving borazine (N3B3H6) and monomeric BH2NH2, are generated with different heating rates.Currently, the slow dehydrogenation kinetics, irreversibility, and formation of volatile materials(trace borazine and ammonia) hav

7、e limited its practicalapplication .To overcome these barriers, tremendous efforts have been devoted to developing new strategies to enhance the hydrogen storage properties of AB in solution and solid state.11Nanoscaffold Mediates Hydrogen Release and theReactivity of Ammonia BoraneAnna G., Li L., e

8、t al Angew. Chem. Int. Ed. 2006, 44, 3578-358212Experimental Mesoporous silica materials have an extremely highsurface area and a highly ordered pore structure, which givethem the appearance of nanochanneled silica scaffolds.The SBA-15 was loaded with AB by dosing the silica scaffold with a saturate

9、d methanolic solution of AB.Because of the porous nature of the silica scaffold, theinternal channels of SBA-15 were filled rapidly by a capillary action directly upon exposure. The sample was dried under vacuum to remove the methanol and produce the SBA-15 coated with AB (1:1 by weight).13141516Amm

10、onia borane for a hydrogen-storage materialthree additional physical obstacles: 1) The rates of H2 release at temperatures below 85oC must be increased 2) borazine formation must be prevented3) reversibility must be demonstratednotable observations: 1) increased rates of H2 release 2) modifications

11、of the nonvolatile polymeric products that lead to a change in the thermodynamics of hydrogen release3) minimized formation of borazine17Substituting H atom in the NH3 groupSuch as: Li(or Na)NH2BH3Xiong ZT., Chen P. et al. Nature Mater. 2008, 7, 138-141. Kang XD., Wang P. et al. Adv. Mater. 2008, 20

12、, 27562759US 2006/0097221 A1Ca(NH2BH3)2H. V. K. Diyabalanage, R. R. Shrestha, et al. Angew. Chem, Int. Ed. 2007, 46, 8995.MeNH2BH3 Me2NHBH3Y. Chen, T. Autrey, et al, J. Am. Chem. Soc. 2005, 127, 3254.18BH3NH3LiH or NaHBall millingLiNH2BH3 or NaNH2BH31920Xiong ZT., Chen P. et al Nature Mater. 2008, 7

13、. 138-141. Xiong ZT., Chen P. et al Nature Mater. 2008, 7. 138-141. 21LiNH2BH3(NH3BH3)Xiong ZT., Chen P. et al Chem. Commun., 2008, 5595559722BH3NH3LiH or NaHStirring in THFLiNH2BH3 or NaNH2BH3suspensionvacuum distillationXiong ZT., Chen P. et al Chem. Commun., 2008, 5595559723Xiong ZT., Chen P. et

14、al Chem. Commun., 2008, 5595559724LiNH2BH325US 2006/0097221 A1Reading is important!Lithium-Catalyzed Dehydrogenation of AmmoniaBorane within Mesoporous Carbon FrameworkLi L., Yao XD, et al. Adv. Funct. Mater. 2009, 19, 265271Combination of the above methods26Two notable phenomena associated with thi

15、snew AB system: i) a synergetic effect of nanostructure confinement and Li catalysis that significantlyenhances the dehydrogenation kinetics of AB; ii) the suppression of volatile products such as borazine and NH3. Li L., Yao XD, et al. Adv. Funct. Mater. 2009, 19, 26527127282930BH3NH3CoCl2 or NiCl2Stirring in THFsuspensionvacuum distillationcoprecipitationNi- or Co- doped BH3NH3He T., Chen P, et al. Chem. Mater. 2009, 21,