title: Metal borohydride formation from aluminium boride and metal hydrides.
abstract: Metal borides are often decomposition products from metal borohydrides and thus play a role in the reverse reaction where hydrogen is absorbed. In this work, aluminium boride, AlB2, has been investigated as a boron source for the formation of borohydrides under hydrogen pressures of p(H2) = 100 or 600 bar at elevated temperatures (350 or 400 °C). The systems AlB2-MHx(M = Li, Na, Mg, Ca) have been investigated, producing LiBH4, NaBH4and Ca(BH4)2, whereas the formation of Mg(BH4)2was not observed at T = 400 °C and p(H2) = 600 bar. The formation of the metal borohydrides is confirmed by powder X-ray diffraction and infrared spectroscopy and the fraction of boron in AlB2and M(BH4)xis determined quantitatively by11B MAS NMR. Hydrogenation for 12 h at T = 350-400 °C and p(H2) = 600 bar leads to the formation of substantial amounts of LiBH4(38.6 mol%), NaBH4(83.0 mol%) and Ca(BH4)2(43.6 mol%).
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, DK-8000 Aarhus, Denmark. trj@chem.au.dk.
authors.forename: Kasper T
authors.identifier: http://orcid.org/0000-0002-1970-6703
authors.initials: KT
authors.lastname: Møller
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, DK-8000 Aarhus, Denmark. trj@chem.au.dk.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Fogh
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, DK-8000 Aarhus, Denmark. trj@chem.au.dk.
authors.forename: Mark
authors.identifier: http://orcid.org/0000-0003-2677-3434
authors.initials: M
authors.lastname: Paskevicius
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, DK-8000 Aarhus, Denmark. trj@chem.au.dk.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Skibsted
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, University of Aarhus, DK-8000 Aarhus, Denmark. trj@chem.au.dk.
authors.forename: Torben R
authors.identifier: http://orcid.org/0000-0002-4278-3221
authors.initials: TR
authors.lastname: Jensen