Dissertation > Excellent graduate degree dissertation topics show

Study on the NOx Storage and Sulfur Resistance of the Rare-Earth Containing La0.7Sr0.3Co1-xFexO3 Perovskite-type NOx Traps

Author: WangShao
Tutor: LiXinGang
School: Tianjin University
Course: Industrial Catalysis
Keywords: sol-gel method perovskite NOx storage sulfur resistance
CLC: O643.36
Type: Master's thesis
Year: 2010
Downloads: 36
Quote: 0
Read: Download Dissertation

Abstract


A series of perovskite-type catalyst La0.7Sr0.3Co1-xFexO3 with different pH value （pH=4.6 and 9） was prepared by sol-gel method, as well as with the various calcination condition. Three phenomenon were aroused by the involvement of the element Fe: i) increasing the reunion degree of perovskite; ii) declining of the specific surface area; iii) the reduction of amount of SrCO3. Especially, the sample of La0.7Sr0.3Co0.8Fe0.2O3, after calcination in flowing air using tubular furnace and pH value of 9, showed much good NOx storage capacity and oxidizability to NO2. It is because of its uniform particle size, i.e. diameter around 40～80 nm, the big specific surface area （21.9 m2/g）, and the perfect perovskite structure.For the reason of security, a new calcined process, which is confirmed by the TG-DTA experiment, was employed to synthesize the La0.7Sr0.3Co0.8Fe0.2O3 catalyst. The results of XRD and SEM show that, the sample preparing with the new method has bigger BET surface and better crystal structure. The diameter of the sample is round 80nm, and only the trace amount of the SrCO3 phase exists on the catalyst. As shown in the results of the NOx storage tests, these samples presented both good NOx storage capacity and high NO convertion to NO2. And, The NSC of the sample with pH=9 is 378μmol/g, and its NO conversion reached 69.8 %. After the pretreatment in SO2/O2, the crystal structure of the samples had not change, and their NSC decreased little, presenting good sulfur-resistance. Furthermore, the sample with ph=9 maintained the convertion of NO in a high level. Combined with the results of the FR-IR, H2-TPR, O2-TPD, and XPS characterization, it can be concluded that the amount of carbonate formed by the new preparation method is less than before, and NOx can be stored as the bulk nitrates on the surface of the perovskite. After sulfation, only a small amount of sulfate were formed, the active site of the perovskite on the catalyst was remained without distroyment, which makes the sample keeping high NOx storage capacity and NO convertion.The final work in this study is to substitute various content of Co with Fe. It was found that the value of NSC decreased following the increase of the proportion of Fe. When the proportion of Fe was not less than 0.2, the catalyst presented a high sulfur resistance. The perovskite structure on the surface of the samples could be damaged by the deep sulfation degree such as exposing in SO2/O2 atmosphere more than 2 h. Considering that the NOx storage process happened at the interface of “gas/perovskite”phases, if the surface of the perovskite crystallites was fully sulfated and covered by sulfates, the active sites for NOx storage would drop sharply inducing in the serious sulfur poison.

Related Dissertations

  1. Study on the Synthesis Bi3.25La0.75Ti3O12（BLT） Nanotubes and Nano Wires,TB383.1
  2. Preparation and Photocatalytic Properties of Semiconductor Oxides,O643.36
  3. Cobalt Ferrite and Its Performance,O611.4
  4. Synthesis, Conducting Properties and Application of Bax Ce0.8Y0.2O3-α + yZnO,TQ174.1
  5. (Class ) perovskite -type oxides catalytic elimination of N 2 O,X701
  6. The Research on Preparation Technology and Sintering Behavior of Rare Earth Aluminates (Dy3Al5O12、 NdAlO3、LaAl11O18),TB383.3
  7. Studies of High Refractive Index Materials Prepared by Nano ZrO2 and TiO2 Hybrid Silicone Epoxy Resin,TB383.1
  8. Preparation and Characterization of Al2O3/C Hybrid Aerogels and Al2O3 Aerogels,O648.17
  9. The Study on Properties of Desulfurization and Denitrification by Mn/Al Catalysts,X773
  10. Investigation into ZnO Thin Film Transistors Prepared by Sol-gel Method,TN321.5
  11. Modified LaMnO 3 perovskites for catalytic combustion of low concentration methane,O643.36
  12. Sol - gel method p -type ZnO films,O484.1
  13. Storage-stable organic / inorganic hybrid polymers and their light-cured coating application,TQ630.4
  14. The Effect of Pd Doping and Chemical Pd-plating on the Electric-Magneto Transport Properties in LCSMO System,O482.5
  15. Study on the Synthesis of La0.8K（0.2）FeO3 Perovskite Composites and the Photocatalytic Degradation of Dye Wastewater,X703.1
  16. Study of Catalytic Properties of La1-yKyCo1-xFexO3 for Reducing NO by Soot under Lean Burn,TQ426.96
  17. Finishing of Cotton Fabric with Vitamin E by Sol-gel Method,TS195.5
  18. Technology and Properties of vanadium oxide thin films,TB383.2
  19. Synthesis and Characterization of Sb-doped SnO2-（CeO2-TiO2） Composite Thin Films Deposited on Substrates for Antistatic Electricity and UV-Shielding,TB383.2
  20. CaTiO_3-NdAlO_3 Preparation and microwave dielectric properties of ceramics,TQ174.6
  21. Fabrication and Properties of BaZrO3/BaCeO3-Based Composite Proton Conductors,O611.4

CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
© 2012 www.DissertationTopic.Net  Mobile