Catalytic methanolysis of hydrazine borane: a new and efficient hydrogen generation system under mild conditions

Abstract

Safe and efficient hydrogen storage is a major obstacle for using hydrogen as an energy carrier. Therefore, intensive efforts have been focused on the development of new materials for chemical hydrogen storage. Of particular importance, hydrazine borane (N₂H₄BH₃) is emerging as one of the most promising solid hydrogen carriers due to its high gravimetric hydrogen storage capacity (15.4 wt%) and low molecular weight. Herein, we report metal catalyzed methanolysis of hydrazine borane (N₂H₄BH₃, HB) as a fast hydrogen generation system under mild conditions. When trace amounts of nickel(II) chloride (NiCl₂) is added to the methanol solution of hydrazine borane ([HB]/[Ni] ≥ 200) the reaction solution releases 3 equiv. of H₂ with a rate of 24 mol H₂ (mol Ni min)⁻¹ at room temperature. The results reported here also includes (i) identification of the reaction products by using ATR-IR, DP-MS, ¹H and ¹¹B NMR spectroscopic techniques and the establishment of the reaction stoichiometry, (ii) investigation of the effect of substrate and catalyst concentrations on the hydrogen generation rate to determine the rate law for the catalytic methanolysis of hydrazine borane, (iii) determination of the activation parameters (E_a, ΔH^#, and ΔS^#) for the catalytic methanolysis of hydrazine borane by using the temperature dependent rate data of the hydrogen generation.