Theoretical study of hydrogen release from BH₃,NH₃,AIH₃,NH₃,BH₃,PH₃,and AIH₃,PH₃

Abstract

The electronic structure calculations using the B3LYP and MP2 levels of theory with the 6-311++G(d,p) basis set have been used to predict the molecular mechanism of hydrogen release from borane amine (BH₃NH₃), alane amine (AlH₃NH₃), borane phosphine (BH₃PH₃) and alane phosphine (AlH₃PH₃) in systems without and with the borane (BH₃), ammonia (NH₃), alane (AlH₃) or phosphine (PH₃) molecules. The calculated results demonstrate that the BH₃, NH₃ and AlH₃ compounds can play the role of an efficient catalyst for hydrogen release from the BH₃NH₃, AlH₃NH₃, BH₃PH₃ and AlH3PH3. A comparison among the BH₃, NH₃ and AlH₃ catalysts, it was found that the NH3 is the efficient catalyst in the AlH₃NH₃ and AlH₃PH₃ systems. The BH₃ and AlH₃ are the efficient catalysts in the BH₃NH₃ and BH₃PH₃ systems, respectively. The lowest activation energies for hydrogen release from the BH₃NH₃, AlH₃NH₃, BH₃PH₃ and AlH₃PH₃ are 23.62, 24.52, 29.26 and 28.26 kcal/mol, respectively. In addition, the highest calculated rate constants for hydrogen release from the BH₃NH₃, AlH₃NH₃, BH₃PH₃ and AlH₃PH₃ are 2.37x10⁻⁵, 6.87x10⁻⁷, 1.14x10⁻⁹ and 4.17x10⁻⁹ s⁻¹, respectively.