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

• Published in: International journal of hydrogen energy Vol. 39; no. 8; pp. 3830 - 3836
• Main Authors: Yu, Lin, Matthews, Michael A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 06.03.2014; Elsevier
• Subjects: Accounting; Alternative fuels. Production and utilization; Applied sciences; Dissolution; Energy; Exact sciences and technology; Fuels; Hydrogen; Hydrogen storage; Hydrogen-based energy; Hygroscopicity; Reactor model; Reactors; Relative humidity; Sodium; Sodium borohydride; Water vapor; Hydrogen storage; Sodium borohydride; Water vapor; Reactor model; Hydrogen; Hydroborates; Hydrogen production
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.12.147

This paper reports new data on the production of hydrogen from water vapor plus NaBH4, or NaBH4 + 10% CoCl2. Data were collected with the aid of an isothermal semi-batch reactor with in-situ H2 rate measurement. The reaction of NaBH4 to generate H2 proceeds via three steps: deliquescence, dissolution and reaction. The deliquescence regime of NaBH4 in the presence of 10 weight percent CoCl2 is defined. The H2 yield is quantified at various reaction conditions (reaction temperature 70–120 °C, relative humidity 31–69%). CoCl2 significantly accelerates the rate of H2 production compared to deliquescence + reaction of pure NaBH4. It is also found that a combination of high temperature and high relative humidity contributes to high H2 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 NaBH4 is developed. The model captures the dissolution + reaction step as well as reaction-only step and was validated by experimental data. •New data on hydrolysis of NaBH4 + CoCl2 with water vapor.•Deliquescence regime defined for this solid mixture.•CoCl2 significantly accelerates the rate of hydrolysis.•A reactor model accounting for deliquescence, solid dissolution, and hydrolysis.