Title Page
Abstract
Contents
Chapter 1. Introduction 11
1.1. The urgent need of CO₂ free energy to address the climate crisis 11
1.2. The cost of CO₂ free energy 14
1.3. Electrochemical CO₂ conversion as value-adding method 18
1.4. Limitation of electrochemical CO₂ reduction 24
1.5. Scope of thesis 29
Chapter 2. Redox-neutral Electrochemical Production of Dimethyl Carbonate. 31
2.1. Introduction 31
2.2. Design strategy for DMC synthesis. 34
2.3. Electrochemical investigation. 39
2.4. Mechanistic study of DMC synthesis. 59
2.5. Role of CO₂ in DMC synthesis system. 67
2.6. Economic benefits and expandability of DMC synthesis system. 70
2.7. Conclusion 77
2.8. Methods 78
Chapter 3. Redox-neutral Electrochemical Production of Ethylene Carbonate. 82
3.1. Introduction 82
3.2. Overview of the developed process 87
3.3. Role of Succinimide in ethylene carbonate production. 90
3.4. Simultaneous separation and utilization of ethylene carbonate. 107
3.5. Techno-economic analysis and life-cycle analysis of bishydroxyurethane production. 116
3.6. Conclusion 124
3.7. Methods 125
Chapter 4. Concluding remarks 144
Bibliography 145
국문 초록 153
Figure 1.1. CO₂ emissions from energy production and low-carbon emission energy production. (a) CO₂ emission by sector (b) CO₂ emission per 1 kWh electricity... 13
Figure 1.2. Levelized cost of electricity production of South Korea in 2025. 17
Figure 1.3. Schemitic of electrochemical CO₂ conversion. 21
Figure 1.4. Electrochemical CO₂ conversion prouducts depending on inserted number of electrons. 22
Figure 1.5. Increasing selectivity of electrochemical C-C bond formation. (a) Copper catalyzed CO₂ reduction to CO and CO dimerization. (b) Theoretical overpotential... 23
Figure 1.6. Electron normalized market price of electrochemical CO₂ conversion products. 27
Figure 1.7. Expected revenue of electrochemical CO₂ conversion products. 28
Figure 2.1. The schematic depicts a redox-neutral electrochemical system for synthesizing dimethyl carbonate (DMC). It involves the integration of the CO₂... 37
Figure 2.2. The schematic illustrates the sequential movement of electrons through the CO₂/CO reduction reaction, the M(0)/M(II) redox cycle, and the X-/X₂ redox... 38
Figure 2.3. The average values of DMC Faradaic efficiency were evaluated using five different supporting electrolytes. In the case of NaClO₄, no oxidant was... 42
Figure 2.4. Photographs of reaction solutions after bulk electrolysis. As the DMC FE increases, there is a noticeable change in the solution's color from reddish orange to... 43
Figure 2.5. Cyclic voltammogram of the Br₂ evolution reaction at the anode. 44
Figure 2.6. The average Br₂ evolution efficiency at the anode. 45
Figure 2.7. Cyclic voltammetry of reduction reaction at the gold electrode. 48
Figure 2.8. Faradaic efficiency of CO₂ reduction to CO (red) at the gold electrode. 49
Figure 2.9. Faradaic efficiency of DMC production with four different catalyst dispersed in the electrolyte solution. 53
Figure 2.10. Photographs of one-pot electrochemical cells composed of a cathode (yellow), a anode (black), Pd/C catalyst in solution. 54
Figure 2.11. Photographs showing cathodic deposition of catalyst after bulke lectrolysis. 55
Figure 2.12. Faradaic efficiency of DMC wtih different amount of Pd/C catalyst in electrolyte solution. 56
Figure 2.13. Mass spectra of DMC produced with ¹²CO₂ and ¹³CO₂. 57
Figure 2.14. Faradaic efficiency of DMC with different current density. 58
Figure 2.15. Mechanism of redox-neutral electrochemical DMC synthesis. 62
Figure 2.16. Oxidative carbonylation of CO to DMC and DMO. 63
Figure 2.17. Mass spectra of butyl methyl ether resulted from methoxide capturing with 1-iodo butane. 64
Figure 2.18. Chemical and electrochemical investigation of DMC synthesis mechanism. (a) photographs of solutions containing different reactants. (b) cyclic... 65
Figure 2.19. Gas chromatography traces of the three different solutions. 66
Figure 2.20. Role of CO₂ in suppressing side reaction of methoxide. (a) Schematics showing reaction between methoxide and bromine in the absence of CO₂. (b)... 69
Figure 2.21. Comparison of faradaic efficiency and current density with previously reported electrochemical DMC synthesis. 73
Figure 2.22. Faradaic efficiency of CO₂ conversion to CO in methanol and ethanol solution. 75
Figure 2.23. Mass spectra of synthesized DEC. 76
Figure 3.1. Net market price normalized by the required total number of electrons (blue) and the required number of electrons (pink) per 1 molecule of CO₂ for... 85
Figure 3.2. Average faradaic efficiencies (blue for H₂, pink for Br₂, RX1) and yields (dark cyan, RX2-RX4) of individual steps. Scatter points represent individual values... 86
Figure 3.3. Thermochemical synthesis of ethylene carbonate from CO₂ and epoxide. 88
Figure 3.4. The schematic illustrates of electrochemical ethylene carbonate production process. 89
Figure 3.5. Schematic diagramshowing desired chemical reactions (solid arrow) and possible side reactions (dotted arrow) throughout the RX1-RX4 steps. 94
Figure 3.6. Cyclic voltammograms of the hydrogen evolution reaction at a nickel foam cathode in catholyte containing different concentrations of succinimide (0 M,... 95
Figure 3.7. ¹³C NMR results of ¹³CO₂ under different conditions. The black line shows the NMR result of ¹³CO₂-purged anhydrous DMSO. The sharp peak near 125... 96
Figure 3.8. Photographs before and after two solutions containing 1 M succinimide anion (transparent) and 1 M Br₂ (orange) were mixed. Upon mixing of the two... 97
Figure 3.9. Average yields of bromoethanol (blue) after bromination of ethylene at four different reaction conditions (0.1, 0.5, 1 M Br₂ and 1 M bromo-succinimide). 98
Figure 3.10. Yields of chloroethanol (orange) after chlorination of ethylene with three different concentrations of HClO solution (0.1, 0.5 and 1 M). The HClO... 99
Figure 3.11. Remained unreacted bromine species after bromination of ethylene in the presence (blue) or absence (dark cyan) of the succinimide anion. 100
Figure 3.12. Remained unreacted bromine species after bromination of ethylene using differnt nitrogen bases. 101
Figure 3.13. Yields of bromoethanol and chloroethanol after halogenation of ethylene with bromo-succinimide and chloro-succinimide. 102
Figure 3.14. Yields of ethylene carbonate and ethylene glycol after bromoethanol reacting with CO₂ captured solution at different temperature. 103
Figure 3.15. Yields of ethylene carbonate and ethylene glycol after chloroethanol reacting with CO₂ captured solution at different temperature. 104
Figure 3.16. Yields of ethylene carbonate and ethylene glycol after bromoethanol reacting with NaHCO₃ or Na₂CO₃ in the presence and absence of succinimide. 105
Figure 3.17. Integration reaction steps into a one-pot electrochemical reaction. a, Schematic illustration of the one-pot reaction setup b-c, Faradaic efficiencies of... 106
Figure 3.18. Aminolysis of ethylene carbonate to bishydroxyurethane. 109
Figure 3.19. Mechanism of succinimide catalyzed aminolysis of ethylene carbonate. 110
Figure 3.20. DFT calculation results of succinimide catalyzed aminolysis of ethylene carbonate. 111
Figure 3.21. Investigation of the substrate scope and gram-scale reaction for bishydroxyurethane production. a, Structure and yield of bishydroxyurethanes... 113
Figure 3.22. Schematic diagram showing the further conversion of BBHU-1 to urethane acrylate (upper case) and urethane epoxy (lower case). 114
Figure 3.23. Properties of synthesized urethane polymer. (a) Differential scanning calorimetry (DSC) results and a photograph of the urethane polymer. (b) Tensile test... 115
Figure 3.24. Schematic diagramshowing the bishydroxyurethane production process, which consists of five different sections corresponding to RX1-RX5. 119
Figure 3.25. Net present value (NPV) of the bishydroxyurethane production process over 15 years of operation. 120
Figure 3.26. Capital expenditure (CAPEX) and operating expenditure of the base case scenario. 121
Figure 3.27. The global sensitivity analysis results of NPV for three different mole fractions of ethylene glycol (fEG) in the recycling stream (7, 12, and 35%). 122
Figure 3.28. Global warming potential (left) and fossil resource scarcity (right) of conventional polyurethane monomer (PUM) production and PUM production based... 123