Title Page

Contents

Abstract 14

Chapter 1. Introduction 16

1.1. CO₂ green house gas as global warming component 16

1.2. CO₂ hydrogenation to methanol reaction 18

1.2.1. Methanol 18

1.2.2. CO₂ hydrogenation to methanol reaction 22

1.2.3. Cu-based catalysts 24

1.3. CO₂ hydrogenation to dimethyl ether reaction 28

1.3.1. Dimethyl ether 28

1.3.2. CO₂ hydrogenation to dimethyl ether reaction. 33

Chapter 2. Cu-based core-shell structured catalysts for CO₂ hydrogenation to methanol reaction 36

2.1. Experimental session 36

2.1.1. Catalysts Preparation 36

2.1.2. Catalytic activity measurement 40

2.1.3. Catalyst characterization 42

2.2. Results and discussion 44

2.2.1. Textural and structural properties 44

2.2.2. The effects of basicity of CO₂-TPD 57

2.2.3. Catalytic Performances 59

2.3. Chapter conclusion 67

Chapter 3. The only single catalyst with Cu-based mesoporous core-shell for direct dimethyl ether synthesis from CO₂. 68

3.1. Experimental session 68

3.1.1. Catalysts Preparation 68

3.1.2. Catalytic activity measurement 75

3.1.3. Catalyst characterization 77

3.2. Results and discussion 79

3.2.1. Textural and structural properties 79

3.2.2. The effects of Acidity of NH₃-TPD. 91

3.2.3. Catalytic Performance 94

3.3. Chapter conclusion 101

Chapter 4. Conclusion 102

References 104

논문요약 111

Table 1. Bulk and surface properties of the core-shell structured catalysts with their CO₂ hydrogenation activity. 46

Table 2. Physicochemical properties of the core-shell structured catalysts such as crystallite sizes of the used catalysts measured by XRD analysis and atomic percentages of Cun+ and Cuo species measured by XPS analysis.[이미지참조] 52

Table 3. Binding energy (BE) of the specific Cu, Zn and Al species on the reduced core-shell structured catalysts. 56

Table 4. Three characteristic basic sites on the reduced core-shell structured catalysts measured by CO₂-TPD analysis. 58

Table 5. Catalytic performances for CO₂ hydrogenation to methanol over the CZA/SiO₂, Cu@SiO₂, CZ@SiO₂ and CZA@SiO₂ catalysts. 63

Table 6. Bulk and surface properties of the mesoporous core-shell structured catalysts with their CO₂ hydrogenation activity. 82

Table 7. Binding energy (BE) of the specific Cu and Zn species on the reduced mesoporous core-shell structured catalysts. 90

Table 8. Two characteristic acidic sites on the reduced mesoporous core-shell structured catalysts measured by NH₃-TPD analysis. 93

Table 9. Catalytic performances for CO₂ hydrogenation to dimethyl ether over the Cu-M@SiO₂ nM (M＝Zn, Zn-Al, n＝0.25, 0.5, 1, 2) catalysts. 96

Figure 1. Carbon dioxide emissions (billion tonnes CO₂) with years. 17

Figure 2. Hystoric supply and demand of methanol since 2017. 20

Figure 3. Worldwide methanol consumption by region. 21

Figure 4. Reaction mechanism network of methanol synthesis on Cu(1 1 1). 26

Figure 5. Potential energy diagram. 27

Figure 6. Asia pacific dimethyl ether market size, 2017-2028. 31

Figure 7. Bio based & Synthetic dimethyl ether market, by application, 2017-2027. 32

Figure 8. Reactor type of direct synthesis reaction of CO₂ hydrogenation to dimethyl ether. 35

Figure 9. HRTEM images of the fresh (A) impregnated CZA/SiO₂, (B) Cu@SiO₂, (C) CZ@SiO₂ and (D) CZA@SiO₂ for (1) reduced and (2) used catalysts for 40 h on stream. 48

Figure 10. (A) TPR patterns on the fresh core-shell structured catalysts, (B) CO₂-TPD patterns of the reduced catalysts, (C) HRTEM and EDS line images of the reduced (1)... 49

Figure 11. Wide-angle XRD patterns of the (A) fresh (calcined) and (B) used catalysts. 51

Figure 12. XPS spectra on the reduced core-shell structured catalysts for (A) Cu 2p, (B) Zn 2p and (C) Al 2p species. 55

Figure 13. The (A) CO₂ conversion and (B) Methanol selectivity with reaction time over CZA/SiO₂, Cu@SiO₂, CZ@SiO₂ and CZA@SiO₂ catalysts. Reaction conditions: T... 62

Figure 14. (A) The CO₂ conversion with reaction time over CZA/SiO₂, Cu@SiO₂, CZ@SiO₂ and CZA@SiO₂ catalysts. Reaction conditions: T＝250 ℃, P＝5.0 MPa, WHSV＝2500 mL/gcat·h-1. (B) Wide-angle XRD patterns and (C) TEM images of longrun...[이미지참조] 66

Figure 15. Wide-angle XRD patterns of catalysts where (A) and (B) respectively stand for the fresh and used catalysts. 83

Figure 16. HR-TEM images of (A) CZ@SiO₂ 0.5M, (B) CZ@m-SiO₂ 0.25M, (C) CZ@m-SiO₂ 0.5M, (D) CZ@m-SiO₂ 1M, (E) CZ@m-SiO₂ 2M and (F) CZA@m-SiO₂ 0.5M where (1) and (2) stand for the reduced, 40h used and longrun used catalyst. 86

Figure 17. TEM-EDS line images of reduced (A) CZ@SiO₂ 0.5M and (B) CZ@m-SiO₂ 0.5M catalysts. 87

Figure 18. XPS spectra of (A) Cu 2p and (B) Zn 2p for the reduced catalysts. 89

Figure 19. NH₃-TPD profiles of reduced catalysts 92

Figure 20. The (A) CO₂ conversion and (B) Dimethyl ether yield with reaction temperature over Cu-M@m-SiO₂ nM (M＝Zn, Zn-Al, n＝0.25, 0.5, 1, 2) catalysts.... 95

Figure 21. The (A) CO₂ conversion and (B) selectivity comparison with Cu-M@SiO₂ 0.5M and Cu-M@m-SiO₂ 0.5M (M＝Zn, Zn-Al) over in situ reduced catalysts. Reaction... 99

Figure 22. (A) The CO₂ conversion and Selectivity with reaction time over CZ@m-SiO₂ 0.5M catalyst. Reaction conditions: T＝260 ℃, P＝5.0 MPa, WHSV＝2500... 100