A reactor model for hydrogen generation from sodium borohydride and water vapor

摘要

This paper reports new data on the production of hydrogen from water vapor plus NaBH_4, or NaBH_4 + 10% CoCl_2. Data were collected with the aid of an isothermal semi-batch reactor with in-situ H_2 rate measurement. The reaction of NaBH_4 to generate H_2 proceeds via three steps: deliquescence, dissolution and reaction. The deliquescence regime of NaBH_4 in the presence of 10 weight percent CoCl2 is denned. The H_2 yield is quantified at various reaction conditions (reaction temperature 70-120 ℃, relative humidity 31-69%). CoCl_2 significantly accelerates the rate of H_2 production compared to deliquescence + reaction of pure NaBH_4. It is also found that a combination of high temperature and high relative humidity contributes to high H_2 rate and yield, and either of the two factors dominates the reaction at different conditions. A two-part reactor model accounting for the mechanism of the steam hydrolysis by NaBH_4 is developed. The model captures the dissolution + reaction step as well as reaction-only step and was validated by experimental data.