Quasi in situ Mössbauer and XAS studies on FeB nanoalloy for heterogeneous catalytic dehydrogenation of ammonia borane

Boron-based hydrides for chemical hydrogen storage

“…The second approach is to add into the NH 3 BH 3 matrix a destabilizer such as a metal [131], chloride [132], hydride [133,134], borohydride [135], or amide [136]. For example, He et al [137] showed that loading 2 mol% FeCl 3 to solid-state NH 3 BH 3 accelerates the H 2 generation rate by a factor of about 6 at 60 C. Kalidindi et al [138] and Toche et al [139] showed that CuCl 2 is also an efficient additive. In fact, most of the additives used showed to be active in decreasing the dehydrogenation temperature and in accelerating the H 2 release kinetics.…”

Hydrogen generation from the dehydrogenation of ammonia–borane in the presence of ruthenium(III) acetylacetonate forming a homogeneous catalyst

“…Once 1.0 equivalent of H 2 is released, the starting material is completely consumed and the spectrum exhibits only signals for the toluene-soluble dehydrogenation products of ammoniaeborane; the broad signals at around 1.4, À5.1 and À12.7 ppm ( Fig. 7a and b) for singly dehydrogenated boron atoms [1,23] of the cyclic intermediates [20,22,42], which further partially dehydrogenate to form polyborazylene as evidenced by two resonances centered at 29.4 and 30.5 ppm (Fig. 7c), characteristics for the cross linked B]N compounds (18e40 ppm) [35,43,44].…”

“…The latter one is a chemically very stable compound with a standard enthalpy of formation of À250.7 kJ/mol [14], too stable to be regenerated to give ammoniaeborane at a reasonable energy expenditure, so that in effect only a maximum of two-thirds of the theoretical hydrogen content of ammoniaeborane can be used. However, efficient and reversible H 2 release can be achieved from dehydrogenation of AB in solution by using heterogeneous catalyst such as Ru [7,15,16], Pd [17,18], Rh [19,20], Pt [21,22], Fe [23], Co and Ni [24] nanoclusters or homogeneous catalyst such as N-heterocyclic carbene (NHC) complexes of Ni [1], Fe [25], Ir [26e28], Pd [29], Ru [30,7]. A recent paper [31] has reported the dehydrogenation of NH 3 BH 3 in diglyme solutions at 70 C using a soluble ruthenium(II) complex as homogeneous catalyst which has been prepared following a multistep synthesis protocol [32].…”

Ammonia Borane Based Nanocomposites as Solid‐State Hydrogen Stores for Portable Power Applications

“…Various approaches have been taken to address the “on‐board” technical challenges (by‐products, kinetics, desorption temperature). These strategies include destabilization by: solubilization in aprotic solvent (e.g., ionic liquids), additives (e.g., metal salts, metallic‐based nanostructures), chemical modification (e.g., amidoboranes), and nanoconfinement (using an inert porous host to confine AB, for example, silica) …”

“…[17,29,30] Va rious approaches have been taken to address the "on-board" technical challenges (byproducts,k inetics,d esorption temperature). Theses trategies included estabilization by:s olubilization in aprotic solvent [31,32] (e.g.,i onic liquids), [33,34] additives (e.g.,m etal salts, metallic-basedn anostructures), [35][36][37][38][39][40][41][42][43][44] chemical modification (e.g.,a midoboranes), [45][46][47][48][49][50][51][52] and nanoconfinement( using an inert poroushost to confine AB,for example,silica). [53][54][55] Carbon, with low weight, high abundance,l ow cost, and low reactivityt owards guest materials is an example of an effectivep orous host for confinement of AB.C arbon cryogels result in depressed dehydrogenation onset temperatures with the suppression of ammonia [56] while activatedc arbon (AC)confined AB apparently beginst or eleaseH 2 at room temperaturew ith one of the decompositions teps involving an acid-base reaction between the AC and the hydridic H dÀ in AB,w hichi nteracts with the H d + of the COO-H groups present in AC.…”