NMR Analysis of Various Amine-CO -H O Systems 2 2 Interactions for Studies of Vapour-Liquid Equilibrium and Catalyst Aided and Unaided Solvent Regeneration A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy In Engineering University of Regina By Huancong Shi Regina, Saskatchewan December, 2013 UNIVERSITY OF REGINA FACULTY OF GRADUATE STUDIES AND RESEARCH SUPERVISORY AND EXAMINING COMMITTEE Huancong Shi, candidate for the degree of Doctor of Philosophy in Engineering, has presented a thesis titled, NMR Analysis of Various Amine-CO -H O Systems Interactions 2 2 for Studies of Vapour-Liquid Equilibrium and Catalyst Aided and Unaided Solvent Regeneration, in an oral examination held on November 8, 2013. The following committee members have found the thesis acceptable in form and content, and that the candidate demonstrated satisfactory knowledge of the subject material. External Examiner: *Dr. Eric Croiset, University of Waterloo Co-Supervisor: Dr. Raphael Idem, Faculty of Engineering & Applied Science Co-Supervisor: **Dr. Paitoon Tontiwachwuthikul, Faculty of Engineering & Applied Science Committee Member: Dr. Renata Raina-Fulton, Department of Chemistry & Biochemistry Committee Member: Dr. Hussameldin Ibrahim, Industrial Systems Engineering Committee Member: Dr. Farshid Torabi, Petroleum Systems Engineering Chair of Defense: Dr. Dongyan Blachford, Faculty of Graduate Studies & Research *via teleconference **Not present at defense Abstract The removal of CO by chemical absorption and regeneration has been 2 researched for decades. CO -amine interactions in solvent chemistry have been 2 studied via the Vapour-Liquid Equilibrium (VLE) model. Databases for VLE models have been generated either through software simulators or conventional pH meter + Nuclear magnetic resonance (NMR) experiments. Studies have focused mostly on single amines solutions (MEA, MDEA, BEA, AMP, etc.) below 40ºC. Limitations have restricted research in VLE modeling. Solvent regeneration or CO stripping studies have also been of research interest for years. However, 2 the heat duty is very high, even with stripping performed at reboiler temperatures around 120-140ºC. Two methods, the conventional (pH + NMR) method and a newly developed NMR calibration method presented, were used to obtain and compare the ion speciation data of VLE model in terms of both accuracy and a wider range of operating conditions. The novel NMR method involved both 1D and 2D NMR methods. The 1D NMR analyses included 13C chemical shifts test samples and area integration tests of the specific 13C NMR peaks for carbamate and bicarbonate/carbonate. The 2D NMR involved 1H vs 1H and 1H vs 13C tests to detect intermolecular interactions. NMR analyses of single and blended solvents showed typical but more accurate concentrations of major ions that changed with CO loading. The application of NMR analysis widened the operating range to 2 i quaternary amine systems and higher temperature regions, for which the ion speciation of the blended amine systems could be completely elucidated and quantified of various MEA-DEAB-CO -H O solutions at 24°C from 40 to 70ºC. 2 2 In solvent regeneration, the apparatus and procedures were used for amine regeneration studies with single and blended amine systems + two specific solid acid catalysts, Al O and H-ZSM-5. The primary amine was not energy efficient 2 3 because of few HCO - ions to reduce the energy requirement for MEAH+ 3 deprotonation. The effect of adding a tertiary amine (in blended amine) facilitated the heat duty reduction because of adding two components, R N and HCO - to cut 3 3 the free energy gaps. DEAB generated more HCO - with tertiary amines resulting 3 in a much lower heat duty, even though MDEA is less energy demanding than DEAB as it is less basic as per the energy diagram. The addition of solid acid catalysts during regeneration results in a further reduction of the energy cost because strong acidic catalysts facilitated the release of medium acidic oxides CO . 2 Al O (Lewis acid) was more effective in the lean region because it replaced the 2 3 role of HCO - (negligible < 0.25); while H-ZSM-5 (Brϕnsted acid) was effective 3 throughout the loading range within (0.15-0.50) because it donated protons. The combination of a blended amine (e.g., MEA-DEAB-CO -H O) with solid acid 2 2 catalysts (especially H-ZSM-5) for regeneration was able to cut the energy cost by up to 60% compared to MEA even at 90ºC, which implies that hot water (95-98ºC) can be used as the heat source instead of steam, reducing plant disruption. ii Acknowledgements I would like to express my gratitude to my co-supervisor, Dr. Raphael Idem, who encouraged me to pursue this Ph.D. programme. This research area of NMR study was a new field for me, which was full of interesting and exciting challenges. I would also like to thank my other co-supervisor, Dr. Paitoon Tontiwachwuthikul, who supported me on this Ph.D. project and encouraged me to publish. They both supported me throughout my studies. Dr. Chuanzhong Wang in the Department of Chemistry helped me with some 2D NMR analysis and 1D NMR analysis for the blended amine systems. The ITC lab manager, Teerat Supap, provided me with useful instruments for NMR analysis. I would like to express my gratitude to them both. Financial support provided by the Faculty of Engineering & Applied Science, Faculty of Graduate Studies and Research (FGSR), and the Natural Science and Engineering Research Council of Canada (NSERC) are gratefully acknowledged for the NSERC – PGSD programme. iii Table of Contents Abstract ........................................................................................................................... i Acknowledgements ....................................................................................................... iii Table of Contents .......................................................................................................... iv List of Tables ................................................................................................................... x List of Figures ............................................................................................................... xii Nomenclature ............................................................................................................. xvi Chapter 1 General Introduction and Background ...................................................... 1 1.1 CO Absorption and Regeneration in post combustion CO capture ....................... 1 2 2 1.1.1 CO capture and Storage (CCS) technology ................................................. 1 2 1.1.2 Solvent chemistry: amine and CO -amine interaction .................................. 2 2 1.1.3 Solvent regeneration or CO stripping technology ....................................... 3 2 1.2. Research Targets and purpose of this study ............................................................ 5 1.3 Background and Analytical methodology, NMR spectroscopy ............................. 12 1.3.1. VLE models of CO - amine Interaction for both absorption and 2 regeneration.......................................................................................................... 13 1.3.2 Targeted Major ions of single and blended Amine-CO -H O systems ....... 18 2 2 1.3.3 Analysis methods: pH + NMR combination, NMR calibration. ................. 18 1.3.4 Ion Speciation tables and plots ................................................................... 20 1.3.5 Common thermodynamic model and catalysis for amine regeneration...... 21 iv 1.4 Thesis objectives and Thesis outline. ..................................................................... 23 1.4.1 Research Objective ..................................................................................... 23 1.4.2 Scope of the thesis ...................................................................................... 23 1.4.3 Thesis outline .............................................................................................. 24 1.5 References .............................................................................................................. 25 Chapter 2 General Literature Review ......................................................... 27 2.1 NMR analysis of amine solutions of VLE models ................................................ 27 2.1.1 NMR analysis of amine-CO -H O systems ................................................ 29 2 2 2.1.2 Reaction Schemes: fundamental chemistry of CO -amine interactions ..... 30 2 2.1.3 VLE model development for ion speciation plots ...................................... 32 2.2 Major NMR analysis of amine by other research groups ...................................... 36 2.2.1 NMR analysis with amine for VLE model ................................................. 36 2.3 NMR analysis of amines and Amine-CO -H O systems at ITC ............................ 42 2 2 2.3.1 NMR analysis of MEA-CO -H O VLE model ........................................... 42 2 2 2.3.2 Novel amine synthesis and NMR identification ......................................... 44 2.3.3 NMR analysis of MEA-MeOH-CO -H O: ................................................. 45 2 2 2.4 NMR analysis of amine-CO -H O systems for other purposes. ............................ 48 2 2 2.5 Summary and Related developments ..................................................................... 55 2.5.1 Summary ..................................................................................................... 55 2.5.2 Related researches within the thesis ........................................................... 55 2.6 Available brief review of catalytic Solvent regeneration ....................................... 57 v 2.7 References .............................................................................................................. 58 Chapter 3: Experimental Section ................................................................. 62 3. 1 NMR experiments (Chapter 4 - 6) ........................................................................ 62 3.1.1 Materials and Chemicals ............................................................................. 62 3.1.2 NMR instruments ........................................................................................ 63 3.1.3 CO loading Tests of samples ..................................................................... 63 2 3.1.4 General NMR analysis procedures (1-6) .................................................... 64 3.2 Solvent regeneration tests/ CO stripping (Chapter 7) ........................................... 69 2 3.2.1 Amine Solution preparation and catalyst selection ..................................... 69 3.2.2 Experimental equipment and procedures for solvent regeneration............. 69 Chapter 4 1D NMR Analysis of DEAB-CO -H O Solution ..................................... 71 2 2 4.1 Introduction ............................................................................................................ 71 4.2 Some Properties of Novel Amine DEAB............................................................... 73 4.2.1 DEAB and chemical reaction schemes ....................................................... 73 4.2.2 DEABH+ dissociation constant determination ............................................ 75 4.2.3 13C NMR analysis of DEAB and HCO - / CO 2- ........................................ 78 3 3 4.2.4 Determination of ion concentration of HCO -/CO 2- and 3 3 DEABH+/DEAB .................................................................................................. 82 4.3 Results and Discussion .......................................................................................... 83 4.3.1 DEABH+ dissociation constant analysis using pH meter ........................... 83 4.3.2. 13C NMR results and pH value of the DEAB-CO -H O systems .............. 84 2 2 vi 4.3.3. A novel 13C NMR calibration curve of the DEAB/BEABH+ system ........ 85 4.3.4. Ion speciation plot of DEAB-CO -H O system using combination of 13C 2 2 NMR analysis and pH test (conventional method) .............................................. 89 4.3.5. Ion speciation plot of DEAB-CO -H O system using a novel 13C NMR 2 2 calibration method ............................................................................................... 92 4.4. Conclusions ........................................................................................................ 97 4.5 Reference ............................................................................................................... 98 Chapter 5 1D NMR Analysis of Blended MEA-DEAB Solutions .......................... 101 5.1 Introduction .......................................................................................................... 101 5.2 Experimental investigation of VLE plots of blended amine system: .................. 105 5.2.1 Chemical Reaction Scheme ...................................................................... 105 5.2.2 Accuracy validation of pH method and NMR calibration analysis. ......... 106 5.2.3 The overall experimental procedures for both methods. .......................... 107 5.2.4 Data Acquisition of Major Ions ................................................................ 109 5.3 Results and Discussion ........................................................................................ 114 5.3.1 NMR calibration of the MEA solution ..................................................... 114 5.3.2 Accuracy validation test for the pH method and NMR calibration method. ............................................................................................................................ 116 5.3.3 The 13C NMR spectra and results of pH and 13C NMR methods. ............ 120 5.3.4 Ion speciation tables and VLE plots of blended amine systems. .............. 128 5.4 Conclusions .......................................................................................................... 139 vii 5.5 References ............................................................................................................ 141 Chapter 6 1D NMR analysis of blended amine systems at higher temperature and introduction to 2D spectra studies.............................................................................. 144 6.1 Introduction .......................................................................................................... 144 6.2 Experimental investigation of 1D and 2D NMR ................................................. 147 6.2.1 Experimental analysis of major ions from blended amine solution .......... 147 6.2.2 Data acquisition method with calibration curves ...................................... 150 6.3 Results and Discussion ........................................................................................ 152 6.3.1 Calibration of MEA and DEAB solutions from 40-70ºC ......................... 152 HCO - .......................................................................................................................... 153 3 CO 2- ........................................................................................................................... 153 3 6.3.2 13C NMR spectra analysis of blended amine samples .............................. 156 6.3.3 Ion speciation table and plots of VLE model from 40-70ºC ..................... 160 6.3.4 Predicted ion speciation table and plots at 90ºC ....................................... 165 6.3.5 Studies of bicarbonate and carbonate ....................................................... 167 6.3.6 2D NMR spectra ....................................................................................... 170 6.4 Conclusion ........................................................................................................... 172 6.5 References ............................................................................................................ 173 Chapter 7 Catalytic and non catalytic solvent regeneration during absorption-based CO capture with single and blended reactive amine solvents ...... 175 2 7.1 Introduction .......................................................................................................... 176 7.2 Experimental Section ........................................................................................... 180 viii