NaBH4is a candidate for H2storage in solid phase. NaBH4hydrolysis readily produces H2 gas and NaBO2which can regenerate NaBH4with pressurized hydrogen and the aid of a reducing agent like Magnesium above 500 C. This paper deals with the NaBH4thermochemical regeneration from the NaBO2eMgeH2ternary system at isothermal temperatures between 558 and 634 C and H2 pressure in the range 2e31 bar. A simplified Langmuir adsorption model has been applied for the interpretation of the in-situ H2pressure variations. The applied model is zero-dimensional but provides a reasonable approach to identify the rate determining step and acquire relevant thermodynamic and kinetic parameters such as equilibrium constant (Keq), Gibbs free energy (DrG 0 ) and reaction rate coefficients (k). The study provides an apparent activation energy and Gibbs free energy of this process of 29.2 kJ/mol and76.9 kJ/mol, respectively.
NaBH4 is a candidate for H2 storage in solid phase. NaBH4 hydrolysis readily produces H2 gas and NaBO2 which can regenerate NaBH4 with pressurized hydrogen and the aid of a reducing agent like Magnesium above 500 C. This paper deals with the NaBH4 thermo- chemical regeneration from the NaBO2eMgeH2 ternary system at isothermal temperatures between 558 and 634 C and H2 pressure in the range 2e31 bar. A simplified Langmuir adsorption model has been applied for the interpretation of the in-situ H2 pressure vari- ations. The applied model is zero-dimensional but provides a reasonable approach to identify the rate determining step and acquire relevant thermodynamic and kinetic pa- rameters such as equilibrium constant (Keq), Gibbs free energy (DrG0) and reaction rate coefficients (k). The study provides an apparent activation energy and Gibbs free energy of this process of 29.2 kJ/mol and 76.9 kJ/mol, respectively.
Thermodynamic and kinetic studies of NaBH4 regeneration by NaBO2–Mg–H2 ternary system at isothermal condition
BARBUCCI, ANTONIO;Paola Carpanese;PANIZZA, MARCO
2014-01-01
Abstract
NaBH4 is a candidate for H2 storage in solid phase. NaBH4 hydrolysis readily produces H2 gas and NaBO2 which can regenerate NaBH4 with pressurized hydrogen and the aid of a reducing agent like Magnesium above 500 C. This paper deals with the NaBH4 thermo- chemical regeneration from the NaBO2eMgeH2 ternary system at isothermal temperatures between 558 and 634 C and H2 pressure in the range 2e31 bar. A simplified Langmuir adsorption model has been applied for the interpretation of the in-situ H2 pressure vari- ations. The applied model is zero-dimensional but provides a reasonable approach to identify the rate determining step and acquire relevant thermodynamic and kinetic pa- rameters such as equilibrium constant (Keq), Gibbs free energy (DrG0) and reaction rate coefficients (k). The study provides an apparent activation energy and Gibbs free energy of this process of 29.2 kJ/mol and 76.9 kJ/mol, respectively.
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