Editing Lithium aluminium hydride (section)

=== Thermal decomposition ===
LAH is [[metastability in molecules|metastable]] at room temperature. During prolonged storage it slowly decomposes to {{chem2|Li3[AlH6]}} (lithium hexahydridoaluminate) and [[Lithium hydride|LiH]].<ref name="Dymova">{{cite journal |author1=Dymova T. N. |author2=Aleksandrov, D. P. |author3=Konoplev, V. N. |author4=Silina, T. A. |author5=Sizareva |author6=A. S. | journal = Russian Journal of Coordination Chemistry | year = 1994 | volume = 20 | pages = 279 }}</ref> This process can be accelerated by the presence of [[catalysis|catalytic]] elements, such as [[titanium]], [[iron]] or [[vanadium]].
[[File:Lialh4 dsc.svg|thumb|[[Differential scanning calorimetry]] of as-received {{chem2|Li[AlH4]}}.]]
When heated LAH decomposes in a three-step [[reaction mechanism]]:<ref name="Dymova" /><ref>{{cite journal | last1 = Dilts | first1 = J. A. | last2 = Ashby | first2 = E. C. | title = Thermal Decomposition of Complex Metal Hydrides | journal = Inorganic Chemistry | year = 1972 | volume = 11 | issue = 6 | pages = 1230–1236 | doi = 10.1021/ic50112a015 }}</ref><ref name="Blanchard">{{cite journal | last1 = Blanchard | first1 = D. | last2 = Brinks | first2 = H. | last3 = Hauback | first3 = B. | last4 = Norby | first4 = P. | title = Desorption of LiAlH<sub>4</sub> with Ti- and V-Based Additives | journal = Materials Science and Engineering B | year = 2004 | volume = 108 | issue = 1–2 | pages = 54–59 | doi = 10.1016/j.mseb.2003.10.114 }}</ref>
{{NumBlk|:|{{chem2|3 Li[AlH4] → Li3[AlH6] + 2 Al + 3 H2}} |{{EquationRef|R1}}}}
{{NumBlk|:|{{chem2|2 Li3[AlH6] → 6 LiH + 2 Al + 3 H2}} |{{EquationRef|R2}}}}
{{NumBlk|:|{{chem2|2 LiH + 2 Al → 2 LiAl + H2}} |{{EquationRef|R3}}}}

{{EquationNote|R1}} is usually initiated by the [[melting]] of LAH in the temperature range 150–170&nbsp;°C,<ref>{{cite journal | last1 = Chen | first1 = J. | last2 = Kuriyama | first2 = N. | last3 = Xu | first3 = Q. | last4 = Takeshita | first4 = H. T. | last5 = Sakai | first5 = T. | title = Reversible Hydrogen Storage via Titanium-Catalyzed LiAlH<sub>4</sub> and Li<sub>3</sub>AlH<sub>6</sub> | journal = The Journal of Physical Chemistry B | year = 2001 | volume = 105 | issue = 45 | pages = 11214–11220 | doi = 10.1021/jp012127w }}</ref><ref>{{cite journal | last1 = Balema | first1 = V. | last2 = Pecharsky | first2 = V. K. | last3 = Dennis | first3 = K. W. | title = Solid State Phase Transformations in LiAlH<sub>4</sub> during High-Energy Ball-Milling | journal = Journal of Alloys and Compounds | year = 2000 | volume = 313 | issue = 1–2 | pages = 69–74 | doi = 10.1016/S0925-8388(00)01201-9 | url = https://zenodo.org/record/1260143 }}</ref><ref name="Andreasen">{{cite journal | last1 = Andreasen | first1 = A. | title = Effect of Ti-Doping on the Dehydrogenation Kinetic Parameters of Lithium Aluminum Hydride | journal = Journal of Alloys and Compounds | year = 2006 | volume = 419 | issue = 1–2 | pages = 40–44 | doi = 10.1016/j.jallcom.2005.09.067 }}</ref> immediately followed by decomposition into solid {{chem2|Li3[AlH6]}}, although {{EquationNote|R1}} is known to proceed below the melting point of {{chem2|Li[AlH4]}} as well.<ref>{{cite journal | last1 = Andreasen | first1 = A. | last2 = Pedersen | first2 = A. S. | last3 = Vegge | first3 = T. | title = Dehydrogenation Kinetics of as-Received and Ball-Milled LiAlH<sub>4</sub> | journal = Journal of Solid State Chemistry | year = 2005 | volume = 178 | issue = 12 | pages = 3672–3678 | doi = 10.1016/j.jssc.2005.09.027 | bibcode = 2005JSSCh.178.3672A }}</ref> At about 200&nbsp;°C, {{chem2|Li3[AlH6]}} decomposes into LiH ({{EquationNote|R2}})<ref name="Dymova" /><ref name="Blanchard" /><ref name="Andreasen" /> and Al which subsequently convert into LiAl above 400&nbsp;°C ({{EquationNote|R3}}).<ref name="Blanchard" /> Reaction R1 is effectively irreversible. {{EquationNote|R3}} is reversible with an equilibrium pressure of about 0.25 bar at 500&nbsp;°C. {{EquationNote|R1}} and {{EquationNote|R2}} can occur at room temperature with suitable catalysts.<ref>{{cite journal | last1 = Balema | first1 = V. | first2 = J. W. | last2 = Wiench | first3 = K. W. | last3 = Dennis | first4 = M. | last4 = Pruski | first5 = V. K. | last5 = Pecharsky | title = Titanium Catalyzed Solid-State Transformations in LiAlH<sub>4</sub> During High-Energy Ball-Milling | journal = Journal of Alloys and Compounds | year = 2001 | volume = 329 | issue = 1–2 | pages = 108–114 | doi = 10.1016/S0925-8388(01)01570-5 | url = https://zenodo.org/record/1260145 }}</ref>