Improvement of reaction kinetics by metal chloride on ammonia and lithium hydride system

Ammonia NH3 and lithium hydride LiH system releases hydrogen even at room temperature to form lithium amide LiNH2. LiNH2 is recycled back to NH3 and LiH below 300 °C under hydrogen H2 flow condition. However, the reaction rate of the system is slow for a practical application. In this work, various kinds of transition metal chlorides were examined as a potential catalyst to improve the kinetics. For hydrogen desorption reaction, the reaction kinetics of titanium chloride TiCl3 dispersing LiH was about 8 times faster than the raw LiH, suggesting that TiCl3 possessed an excellent catalytic effect. In the case of the regeneration reaction, the reaction kinetics was also improved by the addition of TiCl3. It was mainly caused by physical effects in contrast to the hydrogen desorption process, in other words, the small crystallite and/or particle were formed by the milling with the additive.

► Various metal chlorides were systematically investigated as catalyst on the NH3–LiH system. ► TiCl3 drastically improved kinetic properties of the hydrogen desorption reaction. ► The regeneration reaction was also accelerated by TiCl3 due to increase in frequency factor.