상세정보

Nitrogen oxides generated through various emission sources such as incinerators, power plants, and engines are emitted through the process of burning nitrogen contained in fuel. In accordance with the growing interest in the environment and strengthened environmental regulations, research to reduce pollutants is constantly being conducted. As part of this research, various applications are attempting conversion of fuel, and some conversion of fuel has been made from fossil fuel to liquefied natural gas (LNG) and biomass co-firing. However, even after such conversion of fuel, nitrogen oxides are inevitably generated. Nitrogen oxide is a precursor of particulate matter and causes damage to the environment and human being. These include particulate matter, acid rain, depletion of the ozone layer, photochemical smog, and various diseases. Therefore, NH3-SCR (Selective Catalytic Reduction) technology, which can remove these nitrogen oxides most efficiently and economically, is widely used. This is a technology that uses NH3 as a reductant to convert nitrogen oxides into N2 and H2O that are harmless to the environment and human being. Currently, commercial catalysts for SCR are V2O5/WO3/TiO2 and V2O5/MoO3/TiO2. However, it is necessary to develop a catalyst that is applicable in a low temperature range and has durability against poisonous substances.
We tried to overcome this by changing the surface properties of the catalyst by adding a promoter to the V2O5/TiO2 catalyst. In this study, the optimal contents of Nb and Mo as promoter were derived for the VOx/TiO2-based catalyst to improve activity performance at low temperature and durability against sulfur. Each metal was evenly dispersed in TiO2 without agglomeration. Catalysts to which Nb-Mo is added have abundant V non-stoichiometric species, which facilitates the access of reactants and enhances the performance of the catalyst. In addition, the improved redox property and the amount of active oxygen that can easily participate in the reaction were increased, and an increase in acidic site was also confirmed. In order to confirm that durability against sulfur is excellent compared to existing commercial catalysts, catalysts with the same V content were prepared and compared. When poisoning by injecting sulfur, the catalyst to which Nb-Mo was added maintained more than a certain performance for a longer time, and the ability to decompose and regenerate AS/ABS formed on the catalyst surface was also relatively excellent. It was confirmed that this was because Nb and Mo inhibited adsorption of SO2 on the catalyst surface. Therefore, through the synthesis of the promoters, not only the low-temperature performance was increased, but also the durability to SO2 was significantly increased. Through this enhanced catalyst surface property change (compared to existing commercial catalysts), it can be applied to low-temperature applications and can be used for a long time even when poisoned by SO2 contained in exhaust gas.

CHAPTER 1. INTRODUCTION １
 1.1 Background １
  1.1.1 Necessity of nitrogen oxides removal １
  1.1.2 Status of various emission sources １０
 1.2 Properties and formation of nitrogen oxides １３
  1.2.1 Definition of nitrogen oxides １３
  1.2.2 Generation of nitrogen oxides １４
  1.2.3 Formation of nitrogen oxides １７
 1.3 Methods for nitrogen oxides removal ２３
  1.3.1 Pre-combustion control ２５
  1.3.2 Combustion control ２６
  1.3.3 Post-combustion control ３１
 1.4 Selective Catalytic Reduction ３６
  1.4.1 Selective catalytic reduction with HC as a reductant (HC-SCR) ３９
  1.4.2 Selective catalytic reduction with H2 or CO as a reductant (H2-SCR, CO-SCR) ４０
  1.4.3 Selective catalytic reduction with NH3 as a reductant(NH3-SCR) ４２
  1.4.4 Catalysts used in selective catalytic reduction ５０
  1.4.5 Physiochemical property and reactivity of SCR catalysts ５５
 1.5 SCR reaction mechanism ６３
  1.5.1 Langmuir-Hinshelwood assumption mechanism ６５
  1.5.2 Eley-Rideal assumption mechanism ６９
  1.5.3 Dual Eley-Rideal Langmuir-Hinshelwood mechanism ７１
 1.6 Research object and scope ７５
CHAPTER 2. EXPERIMENTAL ７８
 2.1 Catalyst preparation ７８
 2.2 Catalytic activity tests ７９
 2.3 Catalyst characterization ８１
CHAPTER 3. DISCUSSION ８３
 3.1 Enhancement of catalytic activity doping Nb-Mo on V-based catalysts. ８３
  3.1.1 Catalytic activities of catalysts ８３
  3.1.2 Structural and textural properties ８８
  3.1.3 Acidity ９８
  3.1.4 Redox properties １１２
  3.1.5 In-situ DRIFTS study １２２
  3.1.6 Kinetic study １３０
 3.2 Enhancement of SO2 resistance doping Nb-Mo on V-based catalysts. １３３
  3.2.1 SO2 tolerance １３３
  3.2.2 SO2 regeneration ability １３７
CHAPTER 4. CONCLUSION １４１
REFERENCES(OR BIBLIOGRAPHY) １４２