Exhaust energy recovery via catalytic ammonia decomposition to hydrogen for low carbon clean vehicles

Research output: Contribution to journalArticlepeer-review


  • Nahil Serhan
  • Julio da Silva
  • Andrew York
  • Paul Millington

Colleges, School and Institutes

External organisations

  • Johnson Matthey Technol Ctr


The work presented here, demonstrates the on-board exhaust assisted catalytic ammonia (NH3) conversion to H 2-N 2 using either only exhaust heat (decomposition) or by direct reaction with part of the exhaust gas (reforming). The resultant H 2-N 2 gas mixture from the exhaust heat driven thermochemical energy recovery processes contains up to 15% more energy than the reactant NH 3 (i.e. for 1 kW of NH 3 used in the reaction up to 1.15 kW of H 2 is produced). Experimental studies using a rhodium-platinum (Rh-Pt) catalyst and equilibrium calculations in Chemkin using Konnov's 0.6 and Nozari's reduced mechanisms have revealed that complete NH 3 conversion occurs at typical gasoline direct injection (GDI) engine exhaust gas temperatures (450 °C–550 °C). By partially replacing gasoline in GDI engine with the resultant (H 2-N 2 products, up to 30% reduction in CO 2 and fuels consumption can be achieved. Additional benefits can be gained under real engine operation when the benefits of reduced pumping losses, due to intake dilution with H 2-N 2 gas, are also considered. Furthermore, the work demonstrates additional benefits in CO 2 life cycle for the NH 3 use as an energy carrier in transportation and broader combustion power generation systems.


Original languageEnglish
Article number119111
Early online date6 Sep 2020
Publication statusPublished - 1 Feb 2021


  • Ammonia decomposition, Energy recovery, Gasoline engine emission, Hydrogen production, Reforming catalyst