Low-Temperature NOx Reduction by H2 in the Exhaust of Diesel Engines

Authors

S. Kureti, E. Eßer, TU Freiberg; P. Eilts, L. Heckemüller, TU Braunschweig; T. Morawietz, S. Hosseiny, A. Friedrich, DLR Stuttgart

Summary

H2-deNOx technology is designed for low-temperature NOx reduction (T<200 °C) by hydrogen and was validated experimentally for the first time on a diesel engine test bench. In this proof-of-concept study, the best catalyst available, a catalyst developed for H2-ICE, reached peak NOx conversions of more than 95 % in synthetic diesel exhaust gas and N2 selectivities of up to 80 % under relevant conditions. This is noteworthy, as the catalyst tested is not optimized for diesel conditions. Additionally, factors inhibiting the H2-deNOx reaction, such as high CO/ HC contents, were identified and eliminated where possible. From laboratory data using a 1″x2″ honeycomb catalyst, a statistical model was developed to approximate NOx conversion and N2O formation under boundary conditions derived from engine test bench results. The model was validated by stationary and transient tests on the engine test bench using a full-sized 5.66″x6″ honeycomb catalyst....

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