Hydrogen storage in chemical hydrides is tantalizing because the hydrides can be stored at ambient temperature and pressure. However, the detailed mechanism and therefore a kinetic model have been very difficult to determine. Herein we examine two mathematical and theoretical frameworks for extracting kinetic models from experimental data with high-concentration, non-buffered aqueous solutions. In the first approach, we develop non-catalyzed kinetics in a regime where NaBH4 concentration is 10-20wt. %. The result is a classical kinetic power law model incorporating the effects of temperature, initial concentration and pH. In the second approach we employ alternative method, i.e. model-based isoconversional method. The overall kinetics is apparently described by a 'reaction-order' model with temperature dependent reaction order in a wide operating window, i.e. 10-20 wt% NaBH4 solutions at 25-80 0C and 0-50 % conversions.  The two methods, by virtue of their underlying physical assumptions, provide insight into possible fundamental processes of hydrolysis.

Modeling the kinetics of sodium borohydride hydrolysis in concentrated aqueous solutions

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.