Influence of process parameters on enhanced hydrogen evolution from alcoholysis of sodium borohydride with a boric acid catalyst

Abstract

The hydrogen evolution via alcoholysis reaction of sodium borohydride with an H3BO3 catalyst was carried out for the first time. In the process of methanol and NaBH4 (NaBH4-MR), the effects of the H3BO3 and NaBH4 concentration, and temperature parameters were examined and evaluated. The hydrogen yields by the NaBH4-MR, NaBH4 ethanolysis (NaBH4-ER) and NaBH4 hydrolysis reactions (NaBH4-HR) with 0.2 M H3BO3 catalyst are 99, 62, and 88% compared to the theoretical hydrogen yield, respectively. The completion times of the NaBH4-MR using the H3BO3 concentrations of 0.2, 0.4, 0.5, 1 M, and saturated acid solution were about 50, 15, 10, 2 and 1 min, respectively. The hydrogen yields obtained with 50, 15, 10, 2, and 1 min for the same acid concentration values were about 100% compared to the theoretical hydrogen value. By increasing the H3BO3 concentration from 0.2 M to the saturated H3BO3 concentration, the completion time of this NaBH4-MR process was reduced by approximately 50 times, resulting in a significant result. The activation energy (Ea) of the NaBH4-MR with the H3BO3 catalyst was 57.3 kJ/mol.