Presentation on theme: "Kevin Meaux. Alternatives to fossil fuels to power transportation are sought To use hydrogen for fuel, a more effective way of storing H 2 is needed."— Presentation transcript:
Alternatives to fossil fuels to power transportation are sought To use hydrogen for fuel, a more effective way of storing H 2 is needed High volumetric density, hydrogen mass %, stability, and reversibility are desired Liquid and gaseous H 2 are not dense enough Metal hydrides and similar compounds offer potential solutions
For Comparison… descriptionNonhazardous stable white powder 1 Melting point 104 ⁰C (377 K) Density0.78 g/cm 3 Mass % H19.6% 1 Hydrogen Density0.153 g H/cm 3 H 3 N:BH 3  Marder, T., Angewandte Chemie International Edition, 2007, 46, 8116–8118. Mass % H of LiAlH 4 10.6% Mass % H of NaBH 4 10.7% Density of L H 2 0.068 g/cm 3
For effective use, more info is needed on the dehydrogenation process of ammonia borane (AB) Important first steps involve developing a working experimental setup to study this change
Infrared Spectroscopy Schematic http://solidstate.physics.sunysb.edu/book/prob/node111.html Using Transmittance Fourier Transform Infrared Spectroscopy Characterizes a substance by the vibration of its chemical bonds
KBr and NH 3 BH 3 are mixed in a 25:1 ratio KBr alone and the KBr/AB mixture are pressed into a tungsten mesh in different spots Have varied the reference salt, absolute amounts, and ratios Original Experimental Setup
Image produced by Oleg Byl sample reference tungsten mesh grid copper leads for resistive heating Sample is under rough vacuum for analysis (~9E-2 torr) Heated and then allowed to cool under argon (~5 torr) New spectra is taken at room temperature and rough vacuum
Our findings *Literature 2 Assignment 3386NH anti sym stretch 33093337NH sym stretch 32593224??? 31973164??? 2427B 10 H stretch 23802415B 11 H stretch 23502340BH stretch 2116 ??? 1656??? 16041608NH deformation 1591??? 1558 ??? 13761343NH deform 1301NH rock 1252 ??? 11651186BH deform 1060 B 10 H deform 1052B 11 H deform 987B 10 N stretch 968B 11 N stretch 783 ??? 725 ??? 603BH rock *This table compares reference IR peaks for ammonia borane with data gathered for 300K  JJ. Smith, K. S. Seshadri, and David White: J. Mol. Spec., 1973, 45, 327-337.
The 1126,2225, and 2291 peaks shown forming at 433 K correspond to KBH 4 3 The 1959/2029 peaks formed at 913 K are likely the formation of B 11 O 2 /B 10 O 2 anions 4 The other peaks observed at 433 K do not fit with borazine, boron oxides, or boron nitride  I.C. Hisatsune and Noelia Haddock Suarez: Inorganic Chemistry, 1964, 3, 168-174.  K. B. Harvey and N. R. McQuaker: Canadian Journal of Chemistry, 1971, 49, 3272-3281.
Had problems with KBr reactivity in pellet preparation Instead it is prepared on a KBr window Dissolved AB in THF Deposited solution on KBr disk Boiled off THF (67 C) Mounted disk onto mesh Thermocouple KBr Window
2.9 mg NH 3 -BH 3 dissolved in 0.7 mL THF and deposited on KBr disk. KBr disk is mounted on tungsten mesh, on which thermocouple was spot-welded. Sample was heated under 0.1 torr pressure and spectra collected at room temperature.
* Evaporated THF solution on KBr window Pressed KBr PelletLiterature 2 Assignment 3386NH anti sym stretch 328433093337NH sym stretch 324832593224??? 31973164??? 2427B 10 H stretch 237023802415B 11 H stretch 232823502340BH stretch 2116 ??? 1663 1656??? 16041608NH deformation 1591??? 15631558 ??? 139513761343NH deform 1301NH rock 12431252 ??? 112911651186BH deform 10541060 B 10 H deform 1052B 11 H deform 987B 10 N stretch 968B 11 N stretch 783 ??? 725 ??? 670 603BH rock
The new sample prep method shows more clearly resolved peaks The accuracy of temperatures needs to be verified The peaks are shifted somewhat from literature values The spectra demonstrates dehydrogenation with heating Neither the KBH 4 nor BO 2 - peaks are seen
AB can be useful as a hydrogen storage media More work needs to be done in characterizing its dehydrogenation Current method yields noisy spectra but shows potential Will be dealing with the noise issues in the near future
This work was supported by the National Science Foundation under EEC-NSF Grant # 1062943 I would like to thank Dr. Trenary and Dr. Jash for their guidance, as well as Dr. Takoudis and Dr. Jursich for administrating the UIC REU program
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