Title Page

ABSTRACT

Contents

I. BACKGROUND 15

1.1. Emission from light-duty vehicles 15

1.2. CO₂, greenhouse gas 16

II. TWC 18

2.1. Introduction 18

2.2. Materials and Methods 20

2.2.1. Catalyst samples 20

2.2.2. Reactor system 21

2.2.3. Catalyst activity test and characterization 22

2.3. Results and discussion 25

2.3.1. Role of individual reductants on emission of NH₃ and N₂O 25

2.3.2. Pt substituted effect on Pd/Rh catalysts 43

2.4. Conclusion 60

II. CO₂ capture 62

3.1. Introduction 62

3.2. Material and Methods 63

3.2.1. Materials 63

3.2.2. Preparation of Na-ion exchanged 64

3.2.3. CO₂ adsorption and desorption measurements 65

3.3. Results and discussion 65

3.3.1. Different channel framework with similar Si/Al ratios 65

3.3.2. Different Si/Al ratio on Na-ZSM-5 69

3.4. Conclusion 73

Summary in Korean 74

References 77

Table 1. Physicochemical properties (PGM loading and ratio) of commercial three-way catalysts (TWCs). 21

Table 2. Composition of full-feed tests as a function of A/F ratio (0.97 ≤ λ ≤ 1.03), GHSV＝150,000 h⁻¹ 24

Table 3. Composition of simple-feed test with individual and dual reductants at stoichiometric condition (λ＝1.00), GHSV＝150,000 h⁻¹ 24

Table 4. Light-off temperatures (temperature at 50% conversion) for CO, C3H6, C3H8, and NO over commercial aged TWCs[이미지참조] 45

Table 5. Physicochemical properties, CO₂ adsorption and desorption performance of proton and Na-ion exchanged zeolite prepared in this study. 68

Table 6. Physicochemical properties, CO₂ adsorption and desorption performance of Na-ion exchanged ZSM-5 with different Si/Al ratios. 71

Fig. 1. (a) Evolution of atmospheric CO₂ concentration during 1960-2019 measured at the Mauna Loa Observatory (Hawaii). The dashed red line represents monthly means centered on the average of each... 17

Fig. 2. Schematic flow diagram of fixed-bed catalytic reactor for TWC activity test A syringe pump (NE-1000 programmable syringe pump, New Era Pump Systems, New York,... 21

Fig. 3. Light-off curves for (a) NO, (b) CO, (c) C3H6 and (d) C3H8 conversions over commercially aged TWC. Full feed condition: rich (0.97 ≤ λ 〈1.00), stoichiometric (λ＝1.00), and lean (1.00 〈λ ≤ 1.03) at 0.01 intervals,...[이미지참조] 27

Fig. 4. A 3D formation map of NH₃ and N₂O on commercially aged TWC. Full feed condition: rich (0.97 ≤ λ〈1.00), stoichiometric (λ＝1.00), and lean (1.00 〈λ ≤ 1.03) at 0.01 intervals, GHSV＝150,000 h⁻¹ 27

Fig. 5. Formation of (a) NH₃ and (b) N₂O, and (c) N₂ selectivity over commercial aged TWC. Full feed condition: rich (0.97 ≤ λ 〈1.00), stoichiometric (λ＝1.00) and lean condition (1.00 〈λ ≤ 1.03) with 0.01... 29

Fig. 6. Formations of NH₃ and N₂O with single reductants (a) H₂, (b) CO, (c) C3H6 and (d) full mixture feed, together with light-off curves for NO, CO, and HCs conversion over commercially aged TWC. Stoichiometric...[이미지참조] 36

Fig. 7. NH₃ and N₂O formations with (a) H₂ + CO mixture and (b) HC mixture (C3H6 + C3H8) on commercially aged TWC, with matching NO, CO, and HC conversions. Stoichiometric (λ＝1.00 with 1,000 ppm NO, 13.9 %...[이미지참조] 37

Fig. 8. Formation of CO over commercial aged TWC. Feed condition: stoichiometric (λ＝1.00) with H₂ simple feed (pale pink square with solid line; 2,000 ppm H₂ and 500 ppm O₂), C3H6 simple feed (blue circle with solid... 38

Fig. 9. DRIFT spectra of NH₃ intermediates produced by the NO-H₂ reaction at 250 ℃, with (a) NO adsorption 3,000 ppm and (b) H₂ adsorption (10,500 ppm). 41

Fig. 10. DRIFT spectra corresponding to N₂O intermediates produced by the NO-CO reaction at 350 ℃, with (a) NO adsorption (3,000 ppm) and (b) CO adsorption (18,000 ppm). 42

Fig. 11. DRIFT spectra of intermediates of N₂O produced by the NO-C3H6-C3H8 reaction at 350 ℃, with (a) NO adsorption (3,000 ppm) followed by (b) HCs adsorption (960 ppm C3H6 and 240 ppm C3H8)[이미지참조] 42

Fig. 12. Dominant mechanisms and conditions in which NH₃ and N₂O are formed, respectively. 43

Fig. 13. Conversion of CO, C3H6, C3H8, and NO over aged TWCs under the fuel-lean condition (λ＝1.01).[이미지참조] 46

Fig. 14. N₂O and NH₃ emissions from aged TWCs under fuel-lean conditions (λ＝1.01): (a) N₂O formation, (b) corresponding average N₂O selectivity, (c) NH₃ production, and (d) corresponding average NH₃ selectivity. 47

Fig. 15. Conversion of CO, C3H6, C3H8, and NO over aged TWCs under the fuel-rich condition (λ＝0.99).[이미지참조] 48

Fig. 16. N₂O and NH₃ emissions from aged TWCs under fuel-rich conditions (λ＝0.99): (a) N₂O formation, (b) corresponding average N₂O selectivity, (c) NH₃ production, and (d) corresponding average NH₃ selectivity. 49

Fig. 17. Conversion of CO, C3H6, C3H8, and NO over aged TWCs under the stoichiometric condition (λ＝1.00)[이미지참조] 53

Fig. 18. N₂O and NH₃ emissions from aged TWCs under the stoichiometric condition (λ＝1.00): (a) N₂O formation, (b) corresponding average N₂O selectivity, (c) NH₃ production, and (d) corresponding average NH₃ selectivity. 54

Fig. 19. Fresh TWCs' catalytic performance for (a) CO, (b) C3H6, (c) C3H8, and (d) NO conversion, as well as byproduct formation of (e) NH₃ and (f) N₂O, under the stoichiometric condition (λ＝1.00).[이미지참조] 56

Fig. 20. Aging performance in averaged NO conversion and N₂ selectivity comparing fresh and aged TWCs under the stoichiometric condition. 57

Fig. 21. Comprehensive performance of aged TWCs in averaged NO conversion and N₂ selectivity with respect to exhaust condition (λ＝1.01, 1.00 and 0.99, respectively). 59

Fig. 22. Employed zeolites with different channel frameworks 64

Fig. 23. The sequence of synthesis for Na-ion exchanged zeolite 64

Fig. 24. CO₂-breakthrough curve over (a) H-form zeolites and (b) Na-ion exchanged zeolites with different channel frameworks. 67

Fig. 25. (a) Accumulated adsorption capacity of 400 ppm CO₂ as a function of time and (b) CO₂-TPD profile in the He flow as a function of temperature on different zeolites. 67

Fig. 26. CO₂-breakthrough curve over (a) H-form zeolites and (b) Na-ion exchanged zeolites on ZSM-5 with different Si/Al ratios. 70

Fig. 27. (a) Accumulated adsorption capacity of 400 ppm CO₂ as a function of time and (b) CO₂-TPD profile in the He flow as a function of temperature on ZSM-5 with different Si/Al ratios. 70

Fig. 28. (a) Relation between Na contents and Si/Al ratio and linear relationship of Na contents with (b) CO₂ adsorption and (c) CO₂ desorption capacity. 72