Hydrazine Borane and Hydrazinidoboranes as Chemical Hydrogen Storage Materials

Abstract

Abstract:Hydrazine borane N2H4BH3 and alkali derivatives (i.e., lithium, sodium and potassium hydrazinidoboranes MN2H3BH3 with M = Li, Na and K) have been considered as potential chemical hydrogen storage materials. They belong to the family of boron-and nitrogen-based materials and the present article aims at providing a timely review while focusing on fundamentals so that their effective potential in the field could be appreciated. It stands out that, on the one hand, hydrazine borane, in aqueous solution, would be suitable for full dehydrogenation in hydrolytic conditions; the most attractive feature is the possibility to dehydrogenate, in addition to the BH3 group, the N2H4 moiety in the presence of an active and selective metal-based catalyst but for which further improvements are still necessary. However, the thermolytic dehydrogenation of hydrazine borane should be avoided because of the evolution of significant amounts of hydrazine and the formation of a shock-sensitive solid residue upon heating at >300 °C. On the other hand, the alkali hydrazinidoboranes, obtained by reaction of hydrazine borane with alkali hydrides, would be more suitable to thermolytic dehydrogenation, with improved properties in comparison to the parent borane. All of these aspects are surveyed herein and put into perspective.

In situ Synchrotron X-ray Thermodiffraction of Boranes

“…Borohydrides M(BH 4 ) n (with M as an alkali, alkaline-earth or metal element and n = 1, 2, 3 or 4) and borane complexes L-BH 3 (with L as NH 3 or N 2 H 4 ) are typical candidates [2][3][4]. For example, the compounds lithium borohydride LiBH 4 , ammonia borane NH 3 BH 3 (AB) and hydrazine borane N 2 H 4 BH 3 (HB) carry 18.4, 19.5 and 15.4 wt. % H respectively.…”

“…These theoretical hydrogen densities are among the highest. Another example is ammonium borohydride [NH 4 ][BH 4 ] with 24.6 wt. % H, but it is unstable dehydrogenating to AB at sub-zero temperatures [5].…”

“…The potential of these amidoborane and hydrazinidoborane derivatives for solid-state chemical hydrogen storage was successfully assessed. They showed much better dehydrogenation properties than the parent boranes in terms of onset temperature of dehydrogenation and purity of hydrogen [4,16]. Hydrazinidoboranes are also (white) crystalline solids and can be effectively analyzed by X-ray thermodiffraction.…”

Thermogravimetric analysis-based screening of metal (II) chlorides as dopants for the destabilization of solid-state hydrazine borane

“…8 it was first found to be suitable as solid-state monopropellant for rocketry and fast hydrogen generating systems. 9 More recently, it was suggested to be a possible candidate for chemical hydrogen storage, 10 provided it is not used in pristine state. 7 Indeed, better dehydrogenation performance, in terms of onset temperature of reaction and release of unwanted gaseous side-products, can be obtained by adding a destabilizing agent (e.g., LiH, LiBH 4 , NH 3 BH 3 ), 11−13 or by chemically modifying the borane to form hydrazinidoborane derivatives (e.g., LiN 2 H 3 BH 3 , NaN 2 H 3 BH 3 , KN 2 H 3 BH 3 ).…”

Hydrides: Fundamentals and Applications

“…Our goal in assembling this special issue of Energies was to provide readers with a sense of the future directions that can be anticipated in metal hydride research in view of these changes. We hoped to accomplish this by providing a sampling of the variety of cutting-edge research efforts on metal hydrides that are currently underway throughout the scientific world.We are now happy to present the 15 outstanding contributions (13 original research papers and two reviews) that can be found within this special issue [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. With the inclusion of authors from 16 different countries, the issue truly presents a global view.…”