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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 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

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  1. 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

  2. Contents

  3. 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)

  4. 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

  5. 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;

  6. Contents

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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?

  12. Thank you!

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