PNNL

Abstract

There has been a recent concerted call from the scientific community for intensive fundamental studies to develop new approaches and novel materials for hydrogen fuel cells, hydrogen production and storage to move our energy economy from one based on fossil fuels to one based upon hydrogen.1 The challenges put forth have led to our interests in the chemical and physical properties of hydrogen rich amine borane complexes to develop new materials for onboard storage.2 We recently discovered that the kinetics for the thermal dehydropolymerization of ammonia borane, NH3BH3, are accelerated when the material is coated into mesoporous silica.3 These results piqued our interest in understanding catalytic processes which accelerate the kinetics of hydrogen release from amine boranes. Recent work from the Manners’ group suggested that a heterogeneous rhodium species catalyzed the formation of a cyclic dimer and molecular hydrogen from dimethylamine borane (CH3)2NHBH3, (DMAB) in solution at room temperature.4 They reported that the reaction most likely proceeded by a mechanism involving B-N bond formation catalyzed by Rh(0) colloids. While the evidence at hand seemed to suggest a heterogeneous catalyst, a homogeneous catalytic pathway could not be completely ruled out.