Dissertation > Excellent graduate degree dissertation topics show

Study of Deactivation and Regeneration of Pillared Clays Based Catalysts during Selective Catalytic Reduction of Nitric Oxde by Ammonia

Author: YaoYan
Tutor: ShenBoXiong
School: Nankai University
Course: Environmental Engineering
Keywords: nitric oxide selective catalytic reduction pillared clays MnOx-CeO2 deactivation regeneration
CLC: X701
Type: PhD thesis
Year: 2012
Downloads: 48
Quote: 0
Read: Download Dissertation

Abstract


The selective catalytic reduction （SCR） of NOxwith NH3as reductant hasproven to be a promising technology to reduce the NOxemission in the flue gas.Catalysts are critical to selective catalytic reduction of NOx. Much attention ispresently focused on developing catalysts with high activity and good resistant topoison. Since most of the flue gases contain some amounts of ultra-fine particles,sulfur and water after desulfurization and dedust equipment, deactivation of catalystsis inevitable in the using process. Recently, low-temperature SCR has attracted moreand more interests for its low energy consumption. However, the poisoning effects ofsulfur and ash in flue gas has not invested systemly in the low-temperature SCR. Inthis dissertation, pillared clays were prepared and used as catalyst support. Thelab-scale investigations of activity performance and potential deactivation of MnOxbased catalysts were investigated for low-temperature NOx-SCR.The catalysts of Zr-pillared calys （ZrO2-PILC） supported MnOxshowed highDeNOxperformance in the low-temperature （80-240℃） SCR. It was found that theintroduction of Ce could improve the dispersion of MnOx, enhance the oxygenstorage capacity and the adsoroption of NH3, which is beneficial to NOx-SCR. Theresults showed that NOxconversion would be more than90%in the range of180-240℃. The operating parameters, such as NH3concentration and O2concentration on theDeNOxwere also investigated.The comprehensive study of the effects of alkali metals oxides （K2O/Na2O） anddifferent species of potassium （K2SO4, KCl） were conducted over theMn-Ce/ZrO2-PILC catalyst. Activity assessments of poisoned samples indicated thatcatalyst deactivation involves decrease of BET surface area, restraint of adsorptioncapacity of NH3and reduction features of the catalysts. It also showed that Kexhibited greater poisoning effect than Na. Potassium in the form of chloride andsulfate is also a strong poison for the catalyst, and the resultes indicated that thepoisoning mechanism of potassium salt is similar to that of alkali metal oxides. Regeneration of deactivated catalysts were conducted by washing with water anddiluted sulphuric acid. Water washing was a promising method to the catalystsdeactivated with lower molar ratio of poison to Mn, except for the heavily deactivatedcatalyst. Washing with0.1mol/L H2SO4solution could increase the adsorption ofNH3and the catalyst activity was even higher than the fresh one.Alkaline-earth metals could also induce serious deactivation to the NOx-SCRcatalysts. The deposition of poison resulted in pore plugging and decrease of surfaceacidity and low-temperature reducibility. Washing with diluted acid solution, such assulphuric acid and nitric acid, presented to be more effective than water washing.Washing with sulphuric acid could create new acid sites and enhance the adsorptionof NH3, which is beneficial to the NOx-SCR.The effects of H2O and SO2were also investigated in the research. H2O wouldinhibit the catalytic activity, and the effect relateed with vapor content and thereaction temperature. However, the activity restored quickly to its original level aftercutting off of H2O. While the catalyst was sensitive to the SO2in the gas, andpoisoning effect was irreversible. The deposition of ammonium salts on catalystsurface and sulfation of catalyst active phase were found to be the main reasons forthe deactivation of catalysts. Furthermore, thermal treatment and water-washing wereapplied for the regeneration of the SO2-deacivited catalysts. It was found that washingwith water could recover the most catalyst activity, thermal treatment, in contrast, dolittle to the regeneration.

Related Dissertations

  1. The Ah Chengarchitectural Regeneration Design Research Concerned about the Jin Dynasty Culture,TU984.114
  2. Ion Exchange Removal of Hexavalent Selenium in Raw Water,X703
  3. Physical Fields’ Characteristic Study & Structural Optimization of a SCR Denitrification Reactor,X773
  4. Hani settlement vernacular architecture of renewable road,C95
  5. Study on Properties of Ce、Co、Ni/V-W/TiO2 Modified by Composite Sol for Selective Catalytic Reduction,X701
  6. Studies on the Effects of Exogenous Nitric Oxide on Rice under Cadmium Stress,S511
  7. Establishment and Optimization of Genetic Transformation System in Wheat and the Transformation of Ta-APX Gene into Common Wheat,S512.1
  8. Construction of Expression Vector and Genetic Transformation in Phalaenopsis of Phalaenopsis Floral Meristem Identity Gene LFY,S682.31
  9. Study on Agrobacterium-Mediated Transformation of ’Benihonpe’ Strawberry with ALA Synthase Gene,S668.4
  10. Study on Heat Resistance of Chrysanthemum Floral Organ and Effects of Exogenously Nitric Oxide on Heat Resistance of Chrysanthemum,S682.11
  11. Histological Studies of Leaf Regeneration and Fact Ors Influencing the Efficiency Agrobacterium Mediated Transformation in Zizyphus Jujube. Mill.,S665.1
  12. Studies on Agrobacterium-midiated Genetic Transformation in Brassica Campestris Subsp. Chinensis Var. Parachinensis,S634.5
  13. Tissue-engineered Construction and Preliminary Implantation Study of Diamond-like Carbon Films for Artificial Mechanical Valve Applications,R654.2
  14. Research on the Efficiency of Circle-Flow Constructed Wetland Process for Swine Wastewater Treatment and Zeolite Regeneration,X713
  15. Kinase Activities Analysis and Localization of ZmCCaMK Induced by Abscisic Acid in Leaves of Maize Plants,S513
  16. The Expression and Mechanism of NF-κ B and IL-6 after 90% Portal Vein Ligation in Rats,R657.3
  17. Therapeutic Effect and Mechanisms of Derived Mesenchymal Stem Cells in Intracerebral Hemorrhage Rat,R743.34
  18. Study on the Cell Cycle of Liver Cells during Rat Liver Regeneration,Q253
  19. The Regulatory Role of Proliferation and Apoptosis of ERK1/2 and JNK Signaling Pathways in Eight Liver Cell Types during Rat Liver Regeneration,Q418
  20. Studies on the Dissolution of Chitosan in Ionic Liquids,O636.1
  21. Studies on Establishment of Regeneration Systemand Polyploid Induction of Lagerstroemia Indica,S685.99

CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Exhaust gas processing and utilization
© 2012 www.DissertationTopic.Net  Mobile