Boost NOx removal by perovskite-based catalyst in NSR-SCR diesel
aftertreatment systems
Abstract
DeNOx activity of 0.5% Pd–30%
La0.5Ba0.5CoO3/Al2O3
formulation is analysed in single-NSR and combined NSR–SCR systems,
using response surface methodology (RSM). Operational maps are built for
any combination of reaction temperature in the NSR and SCR beds and
H2 concentration. A 4% Cu/SAPO-34 is used as the SCR
catalyst. Results for single-NSR allows tuning operational conditions in
coupled NSR-SCR technology to maximize
NOx-to-N2 conversion, with minimum
NH3 and N2O productions. Control of
H2 concentration and temperature in the NSR system
allows generating the stoichiometric amount of NH3 to
eliminate NOx slipping. The tuned coupled NSR–SCR system achieves high
N2 yield under wide operational range (T=175–425 °C;
CH2=2–4%). Specifically,
N2 yield reaches 92% when NSR and SCR catalysts work at
300 °C and 3% H2 is injected, with NH3
slip and N2O production nearly zero. This provides a
promising alternative for NOx removal in diesel
aftertreatment systems.