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The Introduction of NSR and The Study of CeZr Inhibits the NO X Release. Student: Qingqing Zhang Tutor: Meiqing Shen Environmental Catalysis School of chemical engineering and technology, TJU. 2010.12.02. Contents. NO X Storage-Reduction (NSR).

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The introduction of nsr and the study of cezr inhibits the no x release

The Introduction of NSR and The Study of CeZr Inhibits the NOX Release

Student: Qingqing Zhang

Tutor: Meiqing Shen

Environmental Catalysis

School of chemical engineering and technology, TJU

2010.12.02


Contents

Contents


No x storage reduction nsr

NOX Storage-Reduction (NSR)

  • The NOX storage-reduction (NSR) catalyst was developed for automotive lean-burn engines, and the NOX reduction phenomena were investigated by four steps.

Noble Metal (Pt, Pd, Rh)

Noble Metal (Pt, Pd, Rh)

Lean

Rich (HC, CO, H2)


No x storage reduction nsr1

NOX Storage-Reduction (NSR)

  • NSR catalyst involve three components:

  • Noble metal component: Pt, Rh, Pd;

  • Storage component: alkali- or alkaline-earth species (Ba, K, Ce);

  • Support material: Al2O3, ZrO2, CeO2, TiO2;

  • The typical NSR catalyst: Pt/Al2O3, Ba/Al2O3

HC, H2, CO

NO

Nitrates, nitrites

Nitrates, nitrites

NOX

NO2

N2, H2O

CO2

NO+O2

SM

SM

PM

PM

Support material

Support material

Lean condition

Rich condition


No x storage reduction nsr2

NOX Storage-Reduction (NSR)

  • The influences of temperature and gas(environment) for NSR:

  • Temperature: 350-400℃;

    1. noble metal;

    2. storage component;

    3. support component;

  • Exhaust gas composition:

    1. Reduction gas: H2 > CO > HC;

    2. H2O, CO2;

    3. SO2;


Contents1

Contents


Background

Background

  • Every curve has a lowest point around 145 ℃, and lowest NOX conversion with respect to PA-Ce is smallest.

  • Bidentate nitrites on CeO2 decompose about 200 ℃.

Bidentate nitrites on CeO2

300 ℃

200 ℃

NOX release

100 ℃

Fig. 2 DRIFTS of CeO2 collected with

temperature increasing.

Fig. 1 NOX conversion of each sample with

temperature increasing.


Inhibit the no x release

Inhibit the NOX release

  • We test using CeZr to inhibit the NOX release at low temperature.

  • Every curve have a valley, while CeO2 shows the release phenomena obviously.

  • From the Fig. 3, Ce8Zr2 shows a better NOX storage capacity than CeO2.

  • Ce6Zr4 and ZrO2 adsorb less NOX than CeO2 at low temperature (< 120℃).

  • More ZrO2 is not benefit for NOX storage.

  • Ce8Zr2 can inhibit the NOX release to some extent.

CeO2

Fig. 3 NOX conversion of CeZr samples with

temperature increasing.


Inhibit the no x release1

Inhibit the NOX release

  • Nitrates and nitrites develop with time going on.

Monodentate nitrites on ZrO2: 1462 v(N=O), 1160 v(N-O);

Bidentate nitrites on CeZr: 1200-1185 v(N-O);

Bidentate nitrites on CeO2: 1178 v(N-O);

Bridged bidentate nitrates: 1610, 1220 vas(NO3-) split

Around 1000 vs(NO3-);

Chelate biedntate nitrates: 1520, 1227 vas(NO3-) split, 1030 vs(NO3-) ;

Bidentate nitrites on Al2O3: 1320;

Bridged bidentate nitrates: 1660-1590, 1250-1240, 1060-1000.

  • Bidentate nitrites appear on each sample.

* B. Azambre, J. Phys. Chem. C 2009, 113, 13287-13299

Fig. 4 DRIFTS of CeZr samples collected with temperature increasing.


Inhibit the no x release2

Inhibit the NOX release

Monodentate nitrites on ZrO2: 1462 v(N=O), 1160 v(N-O);

Bidentate nitrites on CeZr: 1200-1185 v(N-O);

Bidentate nitrites on CeO2: 1178 v(N-O);

Bridged bidentate nitrates: 1610, 1220 vas(NO3-) split

Around 1000 vs(NO3-);

Chelate biedntate nitrates: 1520, 1227 vas(NO3-) split, 1030 vs(NO3-) ;

Bidentate nitrites on Al2O3: 1320;

Bridged bidentate nitrates: 1660-1590, 1250-1240, 1060-1000.

  • Bidentate nitrites on CeO2 decompose about 200 ℃.

Bidentate

nitrites

Bidentate

nitrites

Bidentate

nitrites

  • Bidentate nitrites on CeO2 decompose about 200℃;

  • CeZr does not inhibit the bidentate nitrites appearance and decomposition;

* B. Azambre, J. Phys. Chem. C 2009, 113, 13287-13299

Fig. 5 DRIFTS of CeZr collected with temperature increasing.


Inhibit the no x release3

Inhibit the NOX release

  • Conclusion

  • From Fig. 3, Ce8Zr2 inhibits the NOX release at low temperature obviously, however Ce8Zr2 does not inhibit the bidentate nitrites appearance and decomposition.

  • Issues need further addressing:

  • Why dose Ce8Zr2 inhibit the NOX release?

  • How is it happened?


The introduction of nsr and the study of cezr inhibits the no x release

Thank you!


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