Investigation of Reaction Mechanism and Conditions on Ammonia Borane Alcoholysis with Different Alcohols(CH3OH, CH3CH2OH, (CH2OH)2)

In the study, ammonia borane alcoholysis with different types of alcohols (CH3OH, CH3CH2OH, (CH2OH)2) for hydrogen production are investigated, and the effects of different pressures and temperatures on the adsorption properties are also investigated using the DFT calculation and experimental method. In the ammonia borane alcoholysis, NH3BH3 molecules and alcohols molecules (R-OH) are first adsorbed onto the active metal surface, where the hydroxyl groups in the R-OH molecules are activated and the O-H bonds are broken to produce the intermediates H* and *O-R. Further a strong interaction between the B in NH3BH3 and the O in *O-R occurs and the B-N bond is broken, forming the intermediate products *NH3, *BH2-O-R and another H*, H2 molecule is released during B-O bonding with one of the H originated from the hydroxyl group and the other originated from the *HB in the NH3BH3 molecule. The energy barriers for the ammonia borane alcoholysis with CH3OH, CH3CH2OH and (CH₂OH)₂ are 28.23 kcal/mol, 37.5 kcal/mol and 42.32 kcal/mol, respectively, which results in a different alcoholysis rate of ammonia borane AB/CH3OH> AB/CH3CH2OH> AB/(CH2OH)2 at the macroscopic level. The high pressure enhances the adsorption properties of ammonia borane and alcohol molecules, while the high temperature decreases the adsorption properties. The adsorption capacities of ammonia borane and alcohols on the active metal Ru (101) are CH3OH (0.32 mmol/g) < NH3BH3 (1.03 mmol/g) < CH3CH2OH (1.05 mmol/g) < (CH2OH)2 (1.31 mmol/g) specifically. The results of this study provide a theoretical basis for the regulation of hydrogen production from ammonia borane alcoholysis.