Influence of K2NbF7 Catalyst on the Desorption Behavior of LiAlH4

• Main Authors: Nurul Amirah Ali, Noratiqah Sazelee, Muhammad Syarifuddin Yahya, Mohammad Ismail
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2020-06-01
• Series: Frontiers in Chemistry
• Subjects: hydrogen storage; lithium aluminum hydride; desorption; catalyst; metal halide
• Online Access: https://www.frontiersin.org/article/10.3389/fchem.2020.00457/full

In this study, the modification of the desorption behavior of LiAlH4 by the addition of K2NbF7 was explored for the first time. The addition of K2NbF7 causes a notable improvement in the desorption behavior of LiAlH4. Upon the addition of 10 wt.% of K2NbF7, the desorption temperature of LiAlH4 was significantly lowered. The desorption temperature of the LiAlH4 + 10 wt.% K2NbF7 sample was lowered to 90°C (first-stage reaction) and 149°C (second-stage reaction). Enhancement of the desorption kinetics performance with the LiAlH4 + 10 wt.% K2NbF7 sample was substantiated, with the composite sample being able to desorb hydrogen 30 times faster than did pure LiAlH4. Furthermore, with the presence of 10 wt.% K2NbF7, the calculated activation energy values for the first two desorption stages were significantly reduced to 80 and 86 kJ/mol; 24 and 26 kJ/mol lower than the as-milled LiAlH4. After analysis of the X-ray diffraction result, it is believed that the in situ formation of NbF4, LiF, and K or K-containing phases that appeared during the heating process promoted the amelioration of the desorption behavior of LiAlH4 with the addition of K2NbF7.