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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

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;

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?
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