STUDY OF NANO STRUCTURE CATALYZED COMPLEX HYDRIDE (NaAlH₄) FOR HYDROGEN STORAGE

Arun Kumar Thilipan G, D.Pukazhselvan, and O N Srivastava

Hydrogen Energy Centre, Dept of Physics, Banaras Hindu University

Varanasi – 221 005, India.

Email – arunthilip.nano@yahoo.com

Abstract

The growing concerns related to the conventional energy system (production shortage and pollution) mandate the world to afford a more efficient and cleaner energy system for futuristic applications.  Hydrogen is known as the clean fuel with three times higher energy content as compared to conventional hydrocarbon fuels. However, due to the low density of hydrogen, storage of hydrogen becomes an important issue. Metal hydrides are safer and effective for the storage of hydrogen. For mobile application several hydrogen storage media are considered, but they suffer serious setbacks due to irreversible property and low gravimetric storage capacity. Light weighted complex metal hydrides, due to their higher gravimetric storage capacity, are considered promising candidates. Complex Sodium Aluminum Hydride (NaAlH₄) (sodium tetrahydroaluminate) is a promising material for hydrogen storage, however it isn’t considered as a rechargeable carrier due to irreversibility and poor kinetics. By using an appropriate material (transition material, alkali material) as catalyst it can be made reversible. Keeping these aspects in view, in the present investigation, we have catalyzed NaAlH₄ by a number of carbon based catalysts such as multiwalled carbon nanotubes (MWCNT), single walled carbon nanotubes (SWCNT) and activated carbon (AC). It has been observed that MWCNT is the most effective catalyst for improving the kinetics of the hydrogen liberation from NaAlH₄ and to decrease the desorption kinetics. The activation energy of NaAlH₄ gets reduced from 119 kJ/mol to 62 kJ/mol by MWCNT catalyst.

Keywords :  Hydrogen Storage, Complex Hydrides, Kinetics, Catalysis