Modification of the H-2 Desorption Properties of LiAlH4 through Doping with Ti

作者：Langmi Henrietta W; McGrady G Sean^*; Liu Xiangfeng; Jensen Craig M

来源：Journal of Physical Chemistry C, 2010, 114(23): 10666-10669.

DOI：10.1021/jp102641p

Undoped LiAlH4 displays complex thermal behavior in which melting at similar to 170 degrees C is accompanied by spontaneous decomposition to produce Al, H-2, and Li3AlH6: this latter species then decomposes further to LiH, H-2, and Al at similar to 225 degrees C. For undoped LiAlH4, melting corresponds to initial absorption, then release, of the latent heat of fusion as LiAlH4 decomposes to LiH, Li3AlH6, Al, and H-2, and the first three species spontaneously solidify. Doping LiAlH4 with low levels of TiCl3 advances its thermal decomposition by 60-75 degrees C, bringing this event below the melting point of LiAlH4 and uncoupling it from the composite melting-decomposition-solidification event that appears at ca. 170 degrees C for the undoped material. As a result, the desorption of H-2 from both LiAlH4 and Li3AlH6 are each revealed to be intrinsically endothermic events, in contrast with previous reports that described the decomposition of LiAlH4 to produce H-2 as an exothermic process. Accordingly, the release of H-2 by Ti-doped LiAlH4 may be varied and shut off by close control of the sample temperature, in contrast with the undoped material, whose H-2 release characteristics are compromised by its melting, with immediate spontaneous and uncontrolled decomposition.

• 出版日期2010-6-17