Low-Temperature H2-deNOx in Diesel Exhaust

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Abstract
For NOxremoval from diesel exhaust, the selective catalytic reduction (SCR) is the most common abatement technology. However, low engine load scenarios such as city driving and cold start phases demand efficient NOxreduction clearly below 200 °C, which is difficult to achieve with SCR. Hence, this work investigates the potential of the low-temperature NOxreduction with H2in diesel exhaust. A monolithic Pt/WOx/ZrO2catalyst, recently reported as highly active, was evaluated in synthetic and real diesel exhaust. The monolith demonstrated high deNOxactivity between 130 and 215 °C in the synthetic exhaust including peak conversion of 90% with N2selectivity up to 85%. CO/HC components were shown to inhibit the H2-deNOxconversion thus requiring a pre-oxidation catalyst in practice. Furthermore, studies performed in an optical reactor indicated strong heat evolution along the monolith. As a result, the reaction kinetics was accelerated with an enhanced consumption of H2limiting the H2-deNOxefficiency above 200 °C. Stationary tests in diesel engine exhaust substantiated the low-temperature H2-deNOxperformance of the monolith including NOxconversions up to 80% at temperatures as low as 135 °C.
Funding Information
  • Technische Universität Bergakademie Freiberg

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