PNNL

Abstract

Tremendous effort has been devoted to the study of complex and chemical hydrides for hydrogen storage in the past decade[1, 2]. Ammonia Borane (NH3BH3, AB) with a hydrogen content of 19.6 wt % has received significant attention[3-5]. Methods to improve the kinetics of the step-wise dehydrogenation of AB are diverse including the uses of mesoporous frameworks[6], catalysts[7-16], and additives[17]. It was reported that when dissolving in organic solvents AB released hydrogen readily in the presence of transition metal catalysts through the formation of M???HBH2NH3 complex (where M is Ir, Ru, or Ni etc.)[8-10]; Lewis or Brønsted acids, on the other hand, react with AB in solution to form the initiating species (BH2NH3)+[11], which may have the similar function as the [BH2(NH3)2]+BH4- (DADB) in the dehydrogenation of solid AB[17, 18]. However, comparatively little study has been reported on the catalytic dehydrogenation of AB in solid form. Other important but less investigated aspects in the solid-state reaction are the characterizations of functional catalytic species and products from the step-wise dehydrogenation.