Study of On-Board Ammonia (NH3) Generation for SCR Operation 2010-01-1071

Mechanisms of NH₃ generation using LNT-like catalysts have been studied in a bench reactor over a wide range of temperatures, flow rates, reformer catalyst types and synthetic exhaust-gas compositions. The experiments showed that the on board production of sufficient quantities of ammonia on board for SCR operation appeared feasible, and the results identified the range of conditions for the efficient generation of ammonia. In addition, the effects of reformer catalysts using the water-gas-shift reaction as an in-situ source of the required hydrogen for the reactions are also illustrated. Computations of the NH₃ and NOx kinetics have also been carried out and are presented. Design and impregnation of the SCR catalyst in proximity to the ammonia source is the next logical step.

A heated synthetic-exhaust gas flow bench was used for the experiments under carefully controlled simulated exhaust compositions. Operating conditions include rich-lean cycles so that the transient production of NH₃ and the reduction of NOx could be monitored. The bench offered significant flexibility and separate control over the wide ranges of temperatures, flow rates, and the compositions of the mixture. Gas concentrations were measured by Fourier Transform Infrared (FT-IR) Spectroscopy.