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NOx adsorption and diesel soot combustion over La2O3 supported catalysts containing K, Rh and Pt

Paper ID Volume ID Publish Year Pages File Format Full-Text
42770 45940 2009 10 PDF Available
Title
NOx adsorption and diesel soot combustion over La2O3 supported catalysts containing K, Rh and Pt
Abstract

In this work we report results of NOx adsorption and diesel soot combustion on a noble metal promoted K/La2O3 catalyst. The fresh-unpromoted solid is a complex mixture of hydroxide and carbonate compounds, but the addition of Rh favors the preferential formation of lanthanum oxycarbonate during the calcination step. K/La2O3 adsorbs NOx through the formation of La and K nitrate species when the solid is treated in NO + O2 between 70 and 490 °C. Nitrates are stable in the same temperature range under helium flow. However, they become unstable at ca. 360 °C when either Rh and/or Pt are present, the effect of Rh being more pronounced. Nitrates decompose under different atmospheres: NO + O2, He and H2. The effect of Rh might be to form a thermally unstable complex (Rh–NO+) which takes part both in the formation of the nitrates when the catalyst is exposed to NOx and in the nitrates decomposition at higher temperatures. Regarding soot combustion, nitrates react with soot with a temperature of maximun reaction rate of ca. 370 °C, under tight contact conditions. This temperature is not affected by the presence of Rh, which indicates that the stability of nitrates has little effect on their reaction with soot.

Graphical abstractIn this work we report results of NOx adsorption and diesel soot combustion on a noble metal promoted K/La2O3 catalyst. K/La2O3 adsorbs NOx through the formation of La and K nitrate species when the solid is treated in NO + O2 between 70 and 490 °C. However, they become unstable at ca. 360 °C when either Rh and/or Pt are present, the effect of Rh being more pronounced. Regarding soot combustion, nitrates react with soot with a temperature of maximun reaction rate of c.a. 370 °C, under tight contact conditions.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Diesel soot combustion; Nitric oxide adsorption; In situ FTIR characterization; Rh,K,Pt/La2O3 catalysts
First Page Preview
NOx adsorption and diesel soot combustion over La2O3 supported catalysts containing K, Rh and Pt
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 366, Issue 1, 15 September 2009, Pages 166–175
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis