Studies on TiO2 nanoparticles as catalyst for enhanced desorption characteristics of NaAlH4

Abstract

TiO2 (np) has been found to be an effective catalyst over ZrO2 (np) for improving the hydrogen storage characteristics of NaAlH4. TiO2 catalyst reduces the activation energy of NaAlH4 to a better extent than ZrO2. In the reversibly hydrogenated materials, a substantial reduction in the dehydrogenation temperature could be achieved using TiO2 catalyst. Such effect was not observed through ZrO2. The activation energy of the reversibly hydrogenated NaAlH4 catalyzed by TiO2 nanoparticles obtained in the present study (60 kJ/mol H2) is smaller than that of TiO2:NaAlH4 starting material (101.9 kJ/mol H 2). The stability of the intermediate phase Na3AlH 6 in the presence of TiO2 catalyst was studied through TPD and TPA analysis. XRD analysis confirms that only TiO2 gets reduced during dehydrogenation; therefore, the observed effect is attributed to the consequence of reduction of TiO2. © 2011 World Scientific Publishing Company.