Browsing by Author "Yu, Lin"
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- Kinetic modeling of self-hydrolysis of aqueous NaBH4 solutions by model-based isoconversional methodPublication . Retnamma, Rajasree; Novais, Augusto Q.; Rangel, C. M.; Yu, Lin; Matthews, Michael A.The present work reports the kinetic modeling of self-hydrolysis of non-buffered, nonstabilized NaBH4 solutions by model-based isoconversional method. The overall kinetics is described by a ‘reaction-order’ model in a practical operating window of 10-20 wt% NaBH4 solutions at 25-80 ºC and 0-50% conversions. The apparent activation energy and preexponential factor are interrelated through a kinetic compensation effect (KCE). The apparent reaction order remains constant at a given temperature irrespective of extent of conversion and decreases with increase in temperature. It decreases from first-order to 0.26 with increase in temperature from 25 to 80 ºC.
- Kinetics of self-hydrolysis of concentrated sodium borohydride solutions at high temperaturesPublication . Retnamma, Rajasree; Yu, Lin; Rangel, C. M.; Novais, Augusto Q.; Johnson, Karl; Mathews, Michael A.
- Modeling of self-gydrolysis of concentrated sodium borohydride solutionPublication . Retnamma, Rajasree; Rangel, C. M.; Novais, Augusto Q.; Yu, Lin; Matthews, Michael A.In spite of the US DOE recommendation of no-go for sodium borohydride for on-board vehicular hydrogen storage, a great deal of interest remains particularly with view to portable applications. In this work we report on experimental and modeling studies of the kinetics of self-hydrolysis of concentrated NaBH4 solutions (10 – 20 wt %) for temperatures varying between 25 – 80 0C, based on 11B NMR study. The models studied were a power law model and a model which describes the change in order of borohydride during the course of reaction. The modeling results show an increase in rate constant and decrease in the order of reaction with respect to borohydride with temperature, while reverse trends are observed with increasing initial borohydride concentration. A theoretical analysis based on solubility product constant for precipitate formation is also carried out under the studied experimental conditions and is in good agreement with the experimental observation.