Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1995 Simultaneous Water-Gas Shift Reaction and Carbon Dioxide Separation for Direct Hydrogen Production From Synthesis Gas. Chun Han Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Han, Chun, "Simultaneous Water-Gas Shift Reaction and Carbon Dioxide Separation for Direct Hydrogen Production From Synthesis Gas." (1995). LSU Historical Dissertations and Theses. 5954. https://digitalcommons.lsu.edu/gradschool_disstheses/5954 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 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A Bell & Howell Information Company 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 313/761-4700 800/521-0600 SIMULTANEOUS WATER-GAS SHIFT REACTION AND CARBON DIOXIDE SEPARATION FOR DIRECT HYDROGEN PRODUCTION FROM SYNTHESIS GAS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Chemical Engineering by Chun Han B.S., University of Science and Technology of China, 1988 M.S. in Ch.E., Louisiana State University, 1992 May 1995 UMI Number: 9538734 UMI Microform 9538734 Copyright 1995, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 To my parents ACKNOWLEDGEMENTS I would like to express my sincere gratitude and deep respect for my major advisor, Dr. Douglas P. Harrison, who initiated me into this research and guided me with patience, encouragement, and understanding throughout this study. Thanks are due to Dr. Ralph W. Pike, Dr. Geoffrey L. Price, Dr. Gregory L. Griffin, Dr. David M. Wetzel, and Dr. Jeffrey S. Hanor for serving as members of examining committee. The support received from the US Department of Energy (Contract - DE-AC21-89MC26366) is gratefully acknowledged. Further thanks go to the Department of Chemical Enineering for providing financial support during my first semester. I also would like to thank my fellow students, Arpaden Silaban, Marcel Narcida, Alejandro Lopez, and Julie White who provided assistance and shared with me during this research. The help from student workers Matt H. Schumacher, Michael Golda, and Keith Cagnolatti are greatly appreciated. Special thanks are given to our host family, Joyce and George Brown. Our friendship is treasured and will be remembered for life. I must acknowledge the debt I own to my parents and the rest of my family for their support and unconditional love. Most of all, I thank my wife for her infinite patience, endurance and encouragement, without which this dissertation would never have been completed. TABLE OF CONTENTS DEDICATION ............................................ ii ACKNOWLEDGEMENTS ..................................... iii LIST OF TABLES ....................................... vii LIST OF FIGURES ...................................... ix ABSTRACT .............................................. xvi CHAPTER 1 INTRODUCTION ............................. 1 1.1 Hydrogen and Related Technologies ... 1 1.2 Hydrogen Production Via Coal Gasification ........................ 3 1.2.1 Hot Gas Cleanup ............. 4 1.2.2 C02 Removal ................. 5 1.3 Conventional Shift Process and Current Research .................... 6 1.3.1 Theoretical Basis ........... 8 1.3.2 Research Objectives ......... 11 CHAPTER 2 LITERATURE REVIEW ........................ 15 2.1 Water Gas Shift (WGS) Reaction ..... 15 2.1.1 Homogeneous WGS Reaction 16 2.1.2 Catalytic WGS Reaction ...... 16 2.2 Shift Processes ..................... 20 2.2.1 Conventional Shift Processes .................... 20 2.2.2 Novel Shift Concepts ........ 24 2.3 Fundamental CaO Carbonation Studies ............................. 26 2.3.1 Calcination/Carbonation of CaO based Sorbents .......... 26 2.3.2 Structural Changes during Calcination/Carbonation Reactions .................... 31 CHAPTER 3 EXPERIMENTAL APPARATUS AND PROCEDURE .... 41 3.1 Fixed-bed Reactor System ........... 41 3.2 Gas Chromatography System .......... 49 3.3 Sorbent Precursor Description ...... 57 3.4 Sorbent Structural Property Measurement ......................... 60 3.5 Experimental Procedure in Running the Fixed-Bed Reactor System ....... 62 CHAPTER 4 EXPERIMENTAL RESULTS AND DISCUSSION: PRELIMINARY TESTS ........................ 66 iv 4.1 Reactor Temperature Response ....... 67 4-2 GC Analytical Method and Calibration......................... 70 4.3 Reactor Dead Volume Evaluation — Tracer - Response Tests ............. 79 4.4 Preliminary Reaction Tests ......... 82 4.4.1 Calcination and Carbonation Reactions .................... 84 4.4.2 Simultaneous Shift and Carbonation Reactions ....... 93 CHAPTER 5 EXPERIMENTAL RESULTS AND DISCUSSION: SINGLE CYCLE STUDIES ..................... 97 5.1 Reaction Parameters ................ 97 5.1.1 Silaban's Results ........... 98 5.1.2 Characteristics of the Fixed-bed Reactor ........... 100 5.1.3 The Water-Gas Shift Reaction..................... 101 5.1.4 Preliminary Reaction Tests and Final Parameter Selection .... 101 5.2 Shift/Carbonation Reaction Variables ........................... 104 5.3 Experimental Result Reproducibility ..................... 110 5.4 Detailed Parameter Tests ........... 115 5.4.1 Comparison of Different Sorbent Precursors .......... 118 5.4.2 Effect of Calcination Temperature .................. 121 5.4.3 Effect of Calcination Flow R a t e .................... 128 5.4.4 Effect of H20 in the Calcination Sweep Gas .................... 132 5.4.5 Effect of Carbonation/Shift Temperature .................. 141 5.4.6 Effect of Carbonation/Shift Pressure ..................... 146 5.4.7 Effect of Carbonation/Shift Space Velocity ............... 151 5.4.8 Effect of Feed Gas Composition .................. 157 5.4.8.1 Effect of H20/C0 Ratio ................ 157 5.4.9 Effect of Sorbent Particle Size ......................... 166 5.4.10 The Nature of the Shift Reaction..................... 169 5.4.11 Sorbent structural Change Along the Reactor A x i s ...... 172 5.5 Conclusions ......................... 175 v 5.5 Conclusions ......................... 175 CHAPTER 6 EXPERIMENTAL RESULTS AND DISCUSSION: MULTICYCLE TESTS ......................... 177 6.1 Comparison of Sorbent Performance on Five-Cycle Tests ................. 177 6.2 Effect of Carbonation/Shift Temperature ....... 186 6.3 Effect of Carbonation/Shift Space Velocity ...................... 196 6.4 Effect of Carbonation/Shift Gas Composition ..................... 201 6.5 Effect of Calcination Conditions .... 207 6.6 Eleven-Cycle Test Results .......... 215 6.7 Ten Cycle Results Under Isobaric Conditions .......................... 217 6.8 Conclusions .......................... 222 CHAPTER 7 CONCLUSIONS AND RRCOMMENDATIONS ......... 226 REFERENCES ........................................... 233 VITA 237 vi LIST OF TABLES Table 2-1: Surface Area and Pore Volume of CaO ... 34 Table 2-2: Structural Properties of Test Sorbents .............................. 39 Table 3-1: Chemical Analysis of Dolomite (as reported by National Lime Co., Findlay, Ohio) ........................ 59 Table 4-1: GC Operating Conditions ............... 75 Table 4-2: Calibration Gas Compositions (mol percent) ......................,....... 76 Table 4-3: Standard Gas Composition Used for GC Calibration ........................... 77 Table 4-4: Quadratic Constants for GC Calibration ........................... 78 Table 4-5: Summary of Reaction Conditions for the Preliminary Tests ................. 85 Table 5-1: Summary of The Results from TGA Studies (Silaban, 1993) 99 Table 5-2: Reaction Parameters ................... 103 Table 5-3: Feed Gas Composition for Test 18 Using Two Calculation Methods