A Comparison of Ammonia Borane Dehydrogenation Methods for Proton-Exchange-Membrane Fuel Cell Vehicles: Hydrogen Yield and Ammonia Formation and Its Removal

Abstract

Current promising methods to release hydrogen from ammonia borane (NH3BH3, AB; 19.6 wt % H2) including neat thermolysis, thermolysis in ionic liquid bmimCl with or without proton sponge, thermolysis with nano-BN and hydrothermolysis, were investigated for hydrogen yield and ammonia formation. It was found that even trace moisture influences AB dehydrogenation significantly. The hydrothermolysis at 85 °C (13.5 wt % H2, 1 mol % NH3) and thermolysis in bmimCl with 3 wt % moisture at 110 °C (13 wt % H2, 0.2 mol % NH3) methods were found to be the most promising. Since the target for a proton exchange membrane (PEM) fuel cell is an ammonia concentration less than 0.1 ppm, different purification methods were evaluated. Using experiments and simulations, the proposed ammonia removal method, involving absorption in water followed by adsorption on carbon, was optimized and tested. This study demonstrates that, with high hydrogen yield and an effective method to remove ammonia and borazine, AB dehydrogenation is an attractive approach to generate hydrogen for PEM fuel cell vehicle applications.

Mechanistic studies of ammonia borane dehydrogenation

“…7). This observation is repeated twice at w100 C and at w140 C, and is in agreement with previous studies [42]. The first delay may be due to the reactivity of NH 3 with (NH 3 BH 2 (m-H)BH 3 ) to form DADB [41] in the first stage w100 C.…”

Quantum chemical and experimental insights for the ionic liquid facilitated thermal dehydrogenation of ethylene diamine bisborane

“…[2][3][4] Furthermore, the dehydrogenation of AB has certain limitations such as: (a) a complete dehydrogenation temperature at 500 C; and (b) the absence of a method for easily regenerating the end products, such as hydrazine borane. Currently, renewable as well as nonrenewable energy sources are being scrutinized for this purpose.…”

Hydrogen Storage Using Ionic Liquid Media

“…The Lewis adduct of ammonia and borane is an interesting target compound and is in the focus of current research [6,10,17,[39][40][41]. This solid material is air and moisture stable and consists of 19.6 wt-% hydrogen.…”