NOx adsorption study over Pt-Ba/alumina catalysts: FT-IR and pulse experiments

Abstract Adsorption of NO, NO/O 2 , and NO 2 on Pt–Ba–Al–O system is investigated at 350 °C by the transient response method (TRM) and FT-IR spectroscopy. The data suggest that in the presence of oxygen, NO is effectively adsorbed (at a Ba site in proximity of a Pt site) through stepwise oxidation to form at first nitrites that are progressively transformed into nitrates. NO is also oxidized to NO 2 over Pt in the presence of oxygen. NO 2 is directly adsorbed to form Ba nitrates according to a disproportionation reaction, which occurs with the evolution of NO. The stepwise oxidation route seems to play a major role in NO x storage from NO/O 2 mixtures.

[1]  Matsumoto Shin-ichi.  DeNOx catalyst for automotive lean-burn engine , 1996 .

[2]  Koji Yokota,et al.  The new concept 3-way catalyst for automotive lean-burn engine: NOx storage and reduction catalyst , 1996 .

[3]  J. Lunsford,et al.  NO2 Storage and Reduction in Barium Oxide Supported on Magnesium Oxide Studied by in Situ Raman Spectroscopy , 2003 .

[4]  Erik Fridell,et al.  The mechanism for NOx storage , 2000 .

[5]  G. Ghiotti,et al.  Novel low temperature NOx storage-reduction catalysts for diesel light-duty engine emissions based on hydrotalcite compounds , 2002 .

[6]  K. Yokota,et al.  Effect of periodic operation over Pt catalysts in simulated oxidizing exhaust gas , 1998 .

[7]  E. Fridell,et al.  The Influence of Pt Oxide Formation and Pt Dispersion on the Reactions NO2⇔NO+1/2 O2 over Pt/Al2O3 and Pt/BaO/Al2O3 , 2002 .

[8]  M. Shelef.  Selective Catalytic Reduction of NOx with N-Free Reductants , 1995 .

[9]  G. Ghiotti,et al.  FT-IR and TPD investigation of the NOx storage properties of BaO/Al2O3 and Pt-BaO/Al2O3 catalysts , 2001 .

[10]  Erik Fridell,et al.  NOx storage on BaO(100) surface from first principles: a two channel scenario , 2002 .

[11]  E. Tronconi,et al.  NOx Storage Reduction over PtBa/γ-Al2O3 Catalyst , 2001 .

[12]  M. Patterson,et al.  The storage of nitrogen oxides on alumina-supported barium oxide , 2002 .

[13]  E. Tronconi,et al.  On the dynamic behavior of “NOx-storage/reduction” Pt–Ba/Al2O3 catalyst , 2002 .

[14]  P. Schmitz,et al.  NO and NO2 Adsorption on Barium Oxide: Model Study of the Trapping Stage of NOx Conversion via Lean NOx Traps , 2002 .

[15]  J. Lercher,et al.  Elementary steps of NOx adsorption and surface reaction on a commercial storage–reduction catalyst , 2003 .

[16]  R. T. Yang,et al.  The promoting role of noble metals on NOx storage catalyst and mechanistic study of NOx storage under lean-burn conditions , 2001 .

[17]  J. Lunsford,et al.  Mechanism for NO2 Storage in Barium Oxide Supported on Magnesium Oxide Studied by in Situ Raman Spectroscopy , 2002 .