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Condensed Phase Conversion of Bioethanol to 1-Butanol and Higher Alcohols

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Condensed Phase Conversion of Bioethanol to 1-Butanol and Higher Alcohols CONDENSED PHASE CONVERSION OF BIOETHANOL TO 1-BUTANOL AND HIGHER ALCOHOLS By Tyler L Jordison A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of Chemical Engineering – Doctor of Philosophy 2016 i ABSTRACT CONDENSED PHASE CONVERSION OF BIOETHANOL TO 1-BUTANOL AND HIGHER ALCOHOLS By Tyler L Jordison Higher alcohols are important chemical feedstocks as well as potential fuels. With the recent surge in bioethanol production, it would be advantageous to convert bioethanol to butanol and higher alcohols. Results by various authors for a wide range of reaction conditions are presented. For butanol specifically, the highest yields have been obtained with hydroxyapatite, hydrotalcite and alumina-supported nickel catalysts. The literature shows it is a challenge to convert ethanol to butanol, since no one has achieved butanol yields higher than ~30%. In this research project, attention is focused on alumina-supported nickel, since it is robust, stable, and well suited for condensed phase ethanol Guerbet chemistry. Catalyst screening of different compositions was performed and higher alcohol selectivities were analyzed. The 8%Ni/8%La-Al2O3 was proven to produce over 80% selectivity to higher alcohols at 50% ethanol conversion. The impacts of water removal on target alcohol yield with the 8Ni/8La catalyst were investigated in a batch reactor. Removing water decreased selectivity to CH4 and CO2 from 15% without water removal to 8% with water removal. Preliminary kinetics of 1-butanol and 1-hexanol formation were investigated by looking at initial rates of their formation at 215°C, 230°C, and 239°C. Runs with ethanol/acetaldehyde/H2 were performed to investigate the steps of the ethanol Guerbet reaction mechanism. Runs completed at 150°C and 200°C were modeled and rate constants were determined for acetaldehyde hydrogenation, acetaldehyde condensation, and butyraldehyde hydrogenation. It was found ethanol dehydrogenation is in equilibrium and is the rate limiting ii step of the ethanol Guerbet mechanism. The activation energy for ethanol dehydrogenation was calculated to be 150 KJ/mol. Therefore, the effect of H2 on a neat ethanol run was examined and found to have little effect on ethanol conversion rate. Ethanol conversion rates were the same due to the side reaction of H2 with ethanol to CH4 and water, which offsets the negative effect of hydrogen on acetaldehyde formation rate. The presence of excess H2 was found to decrease 1- butanol and 1-hexanol formation rates. iii Copyright by TYLER L JORDISON 2016 iv Dedicated to my parents, loving wife, and beautiful daughter Avery v ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Dennis Miller, for giving me the opportunity to work on this project. I have learned a great amount about research from him during my studies and I am forever grateful for his mentorship. I would like to thank Dr. Carl Lira for his assistance with my VLE modeling. His help with modeling the thermodynamics of my reaction system was a major contribution to helping me accurately characterize it. I want to thank Dr. Lars Peereboom for his training on instruments and also for guidance on experiments. I also want to thank my committee, Dr. David Hodge, Dr. James Jackson, and Dr. Chris Saffron for their support. I would like to thank Evan Wegener for contributing to my catalyst characterization studies. I would like to thank the U.S. Department of Energy (Award no. DE-FG36-04GO14216) and the National Corn Growers Association for financial support of this work. To close, I want to thank my family and friends for their enduring support. I’m grateful for my wife being by my side from beginning to end of this wonderful journey. vi TABLE OF CONTENTS LIST OF TABLES..........................................................................................................................ix LIST OF FIGURES.......................................................................................................................xii 1 Literature Review and Background ......................................................................................... 1 1.1 Introduction ................................................................................................................. 1 1.2 Economics and Energy Yield...................................................................................... 5 1.3 Early Patents ............................................................................................................... 6 1.4 MgO, Mixed Oxide, and Hydroxyapatite Catalysts.................................................... 7 1.5 Homogeneous Catalysis ............................................................................................ 11 1.6 Condensed phase reactions ....................................................................................... 12 1.7 Alumina-Supported-Nickel Catalysts ....................................................................... 12 1.8 Ethanol Reaction with Methanol .............................................................................. 13 1.9 Research Objectives .................................................................................................. 14 1.9.1 Develop Efficient, Condensed Phase Alcohol Condensation Process Using Neat Ethanol .............................................................................................................................. 14 1.9.2 Identify Robust, Stable Catalyst Compositions .................................................... 15 1.9.3 Expand Understanding of Ethanol Guerbet Reaction Mechanism ....................... 15 REFERENCES…………………………………………………………………………………..16 2 Catalyst Screening ................................................................................................................. 20 2.1 Introduction ............................................................................................................... 20 2.2 Experimental ............................................................................................................. 23 2.2.1 Materials and Catalyst Preparation ....................................................................... 23 2.2.2 Catalyst Characterization ...................................................................................... 23 2.2.3 Batch Reaction Studies ......................................................................................... 24 2.3 Results and Discussion ............................................................................................. 29 2.3.1 Catalyst Characterization ...................................................................................... 29 2.3.2 Catalytic Reactions ............................................................................................... 30 APPENDIX………………………………………………………………………………………34 REFERENCES…………………………………………………………………………………..42 3 VLE Modeling ....................................................................................................................... 45 3.1 Introduction ............................................................................................................... 45 3.2 Thermodynamic Modeling of Reaction .................................................................... 46 3.2.1 SR Polar EOS ....................................................................................................... 46 3.2.2 Parameter Estimation ............................................................................................ 49 3.2.3 Applying SR-Polar EOS to Batch Experiments ................................................... 52 3.2.4 Model Validation and Parameter Adjustment ...................................................... 56 3.2.5 Liquid and Vapor Densities .................................................................................. 59 3.2.6 Comparison of SR-Polar EOS analysis with conventional liquid phase analysis 60 3.2.7 Experimental Repeatability................................................................................... 62 3.3 Conclusions ............................................................................................................... 64 vii APPENDIX………………………………………………………………………………………65 REFERENCES…………………………………………………………………………………..78 4 Impact of Water and its Removal on Ethanol Guerbet Reaction ........................................... 80 4.1 Introduction ............................................................................................................... 80 4.2 Experimental ............................................................................................................. 81 4.2.1 Materials ............................................................................................................... 81 4.2.2 Catalytic reactions with water addition ................................................................ 82 4.2.3 Catalytic reactions with water removal ................................................................ 82 4.2.4 Modeling reaction system with water removal ..................................................... 85 4.3 Results and Discussion ............................................................................................. 88 4.3.1 Water addition runs ............................................................................................... 88 4.3.2 Water removal runs ............................................................................................... 91 4.4 Conclusions ..............................................................................................................
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