Working with: Petra de Jongh & Peter Ngene
Employed since: May 2022
Room: DDW 4th floor open area
Metal hydride nanocomposite materials as TM-free catalysts for ammonia synthesis
Ammonia is a well-known and vital part in the production of artificial fertilizers, but recently also acknowledged as a promising hydrogen carrier for the growing renewable energy infrastructure.1,2 Unfortunately, the strong triple covalent bond in N2 combined with high kinetic barriers results in high energy input demand.3 Nowadays, ammonia synthesis is still conducted using fused iron catalysts (Haber-Bosch) or alkali promoted ruthenium catalysts (Kellogg), which require very high temperatures and pressures (400-500°C, 10-30MPa), resulting in these processes amounting to 1-2% of the global energy consumption.1
Alternative catalysts for ammonia synthesis have been emerging, including the use of hydrides, amides and electrides as an alternative to the Haber Bosch process.4 The aim of this project is to develop novel metal hydride based catalysts for ammonia synthesis at moderate temperatures and pressures (<400°C, 1MPa). Starting from alkali metal hydrides, specifically KH confined in graphitic carbon5, we are working towards highly active catalysts for ammonia synthesis and understanding the mechanism thereof. To achieve this, various types of (carbon) supports will be combined with different metal hydrides (LiH, NaH, KH) and investigated in detail. Moreover, long-term catalytic tests will be conducted under different conditions to evaluate catalyst activity and determine the optimal operation window.
This research is part of the EU AMBHER (Ammonia and MOF based Hydrogen for Europe) consortium, which focusses on tackling the short and long-term energy storage challenges.
1. Guo, J. & Chen, P. Catalyst: NH3 as an Energy Carrier. Chem 3, 709–712 (2017).
2. Makepeace, J. W. et al. Reversible ammonia-based and liquid organic hydrogen carriers for high-density hydrogen storage: Recent progress. Int. J. Hydrogen Energy 44, 7746–7767 (2019).
3. Gao, W. et al. Production of ammonia via a chemical looping process based on metal imides as nitrogen carriers. Nat. Energy 2018 312 3, 1067–1075 (2018).
4. Humphreys, J., Lan, R. & Tao, S. Development and Recent Progress on Ammonia Synthesis Catalysts for Haber–Bosch Process. Adv. Energy Sustain. Res. 2, 2000043 (2021).
5. Chang, F. et al. Potassium hydride-intercalated graphite as an efficient heterogeneous catalyst for ammonia synthesis. Nat. Catal. 5, 222–230 (2022).