A study of the ammonia selectivity on Pt/BaO/Al2O3 model catalyst during the NOx storage and reduction process

Abstract

The ammonia selectivity during the cycling NOx storage reduction process over a model Pt/Ba/Al2O3 catalyst was studied. Firstly, it was demonstrated that, whereas the presence of water or carbon dioxide in the gas mixture have a negative effect on the storage step, the effect of these components have different impacts on the NOx efficiency. Due to their involvement in the reverse water gas shift (RWGS) reaction, the absence of water in the gas mixture leads to a drop of the NOx removal whereas without CO2, an increase of the NOx conversion is observed.It was also showed that the reducer (H2) conversion during the short excursion in rich condition is directly correlated to the NH3 emission. NH3 is emitted since hydrogen is not fully converted, whatever the NOx conversion rate. The ammonia pathway is clearly demonstrated and it was claim that, when H2 remains in the reaction mixture, the ammonia production rate is higher than the ammonia reaction with the remaining NOx in order to form N2.

NO storage and reduction properties of model manganese-based lean NO trap catalysts

“…Manganese is also found to be an effective additive for Ba-based LNT catalysts. Le Phuc et al [10][11][12] found that Mn addition to Pt/Ba/Al improved NO x storage capacity and led to an improvement of NO x reduction (conversion and selectivity to N 2 ) at 400 • C. Xiao et al [13] found that Mn/Ba/Al exhibited http://dx.doi.org/10.1016/j.apcatb.2014. 10.001 0926-3373/© 2014 Elsevier B.V. All rights reserved.…”

Experimental and DFT studies on Sr-doped LaMnO3 catalysts for NOx storage and reduction

“…[1][2][3] In a common NSR catalyst, Pt/BaO/Al 2 O 3 , NO is oxidized to NO 2 on Pt and subsequently adsorbed on BaO as a nitrate species in the lean-burn period. Selective catalytic reduction of NO x with NH 3 has been demonstrated to be effective for power plant exhaust gas, while NO x storage reduction (NSR) technology is a promising method to eliminate NO x from diesel vehicles.…”

Non-thermal plasma-assisted NO storage and reduction over cobalt-containing LNT catalysts

“…), the H 2 consumption peak shifted to higher temperatures when NO x storage was performed in the presence of H 2 O and CO 2 . According to work by Courtois et al, reduction of CO 2 (from carbonate) via the RWGS reaction generates CO which is less efficient for the NO x reduction than H 2 , resulting in higher reduction temperatures[41]. Notably, there was no NO x release observed during the H 2 -TPSR process on Pt/Ba/Al and Pd/Co/Ba/Al.…”