Calcium and Iron Oxide Reactivity Studies for Chemical Looping Applications of Clean Energy Conversion DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Niranjani Deshpande Graduate Program in Chemical Engineering The Ohio State University 2015 Dissertation Committee: Professor Liang-Shih Fan, Advisor Professor Bhavik R. Bakshi Professor David L. Tomasko Copyright by Niranjani Deshpande 2015 Abstract The following study entails independent investigations carried out on the reactivity of metal oxides involved in the calcium and chemical looping applications. The Chapters 2 through 5 involve studies on the various applications and aspects of the calcium looping process, and Chapter 6 and 7 discuss two independent investigations of chemical looping oxygen carrier particles. The hydration of calcium oxide (CaO) sorbent has been investigated as a reactivation method in the three step calcium looping process for pre and post combustion carbon dioxide (CO2) capture. The feasibility of the process concept was established using lab scale fixed bed reactor setup, and reactivation of sorbent was achieved with high temperature steam at 500°C over multiple cycles. Further development of the design and operation of a fluidized bed hydrator is reported upon, and fast fluidization regime was identified as the most suitable for a scalable steam hydrator design. Further, a screening study was conducted on multiple egg and sea shells as a renewable source of the CaO sorbent, and excellent reactivity towards CO2 is reported. A novel method for the simultaneous cleanup of CO2, SOx and NOx impurities from coal combustion flue gas is proposed based on the calcium looping process. Proof of concept experiments were performed and 90% CO2 and NO and 100% SO2 removal was demonstrated at 1 atm, 650°C fixed bed experiments, using the calcium sorbent and coal char. For pre- ii combustion application of the calcium looping process (CLP), the fate of sulfurous species is explored, which are formed as a byproduct of the coal to H2 plant with the CLP. The CaS formed in the carbonator at the operating conditions of about 600°C and 23 bar is found to be oxidized to CaSO4 at the calciner operating conditions of the CLP. Treatment options for the purge stream are discussed for the oxidation of unreacted CaS for the safe disposal and integration with the cement industry. In the latter half of the present study, the iron-based metal oxide oxygen carriers are investigated for the chemical looping partial oxidation (CLPO) of CH4 for the production of syngas at elevated pressures. The favorable impact of increased pressure on the redox reaction rates is illustrated through experiments conducted on the iron-titanium complex metal oxide (ITCMO) particles between 1 and 10 atm at 900-950°C in a thermogravimetric setup. The observed change in morphology through SEM and BET analysis at increased pressures is related to the change in reactivity obtained. Lastly, an application of chemical looping gasification (CLG) for the coproduction of H2 and electricity is explored. Specifically, the recyclability of iron based oxygen carriers is investigated in steam redox environments using a specialized thermogravimetric setup. Isothermal tests are conducted for 20 redox cycles using steam as the oxidizing agent for iron and cobalt based metal oxide oxygen carriers at 900°C. MgAl2O4 is used as an inert support. While cobalt-based samples exhibited a loss in reactivity, the excellent recyclability of iron-based oxygen carriers has thus been established. iii This document is dedicated to my little brother, Sukumar. Your memory always inspires me to be a better person, and gives me warmth in my darkest hour. iv Acknowledgments I would like to express my deepest gratitude towards my advisor, Professor Liang-Shih Fan, for offering me the opportunity to work on such a fast and exciting field as chemical looping. I am thankful to the Ohio State University and particularly the William G. Lowrie Department of Chemical and Biomolecular Engineering (CBE) for all the excellent resources and infrastructure that was provided for my easy use that made my graduate research experience such a joy. The state-of-the-art facilities available for students gave me a one of kind experience and a unique flavor of academic research. The CBE family at large, and the Fan group in particular, has helped shape my keen research acumen over the last five years, and instilled in me a deep appreciation of the role of scientific investigation in the overall human development. I would also like to thank Prof. James Rathman, Prof. Bhavik Bakshi, Prof. David Tomasko and Prof. Lisa Hall for serving on my qualifier, candidacy, and dissertation committees. Their discussions always provided me with new ideas to further my research objectives. Dr. Fan has been a constant source of inspiration to me, not only in his role as a direct advisor for my research progress, but also leading by example a life of dedication and discipline. His endless enthusiasm and optimism towards researching solutions for various technological challenges is something I will always aspire to imbibe in myself. v Dr. Nihar Phalak, who was a colleague and a senior in the calcium looping sub-group, shared the better part of his graduate career with mine. Nihar has been invaluable to me in his steadfast friendship, guidance, mentorship and support. I am forever indebted to him for his close involvement and interest in my graduate career development, as well as the close personal friendship, which made my doctoral study a fulfilling and enriching experience. In addition, Dr. Shwetha Ramkumar played a key role in my initial mentoring in the Fan lab. William Wang was always available to discuss any doubts I may have had about the calcium looping system. His in-depth understanding of the process and the power generation process always provided me fodder for new ideas. My other seniors Deepak Sridhar, Ray Kim, Liang Zeng, and Andrew Tong guided me in various capacities, and I am thankful for their guidance and support. I also enjoyed working with Alan Wang for the steam hydration process for reactivation of the calcium sorbent. Dr. Lang Qin provided me her immense expertise in the FIB, EDS and various microscopy techniques. Discussions with her were invaluable to the development of oxygen carrier studies. Ankita Majumder, Elena Chung, and Mandar Kathe were a delight to work with, and transcended the boundaries of co-workers and formed close personal friendships with me. To all three of them, I am forever indebted. Other members of my Fan group family include Dr. Samuel Bayham, Dr. Qiang Zhou, Dr. Dawei Wang, Omar McGiveron, Aining Wang, Cheng Chung, Dikai Xu, and Tien-Lin Hseh; who were always available to discuss any concepts, and lend support in the best team spirit and great rapport. I would also like to mention Nicholas Blum, who I had the pleasure to mentor in his undergraduate research efforts. His insightful questions and keen interest in research were vi extremely helpful for my development as well. I must also mention Brian Yuh, who I mentored for his high school summer internship. The Yuh family’s kindness and warmth will stay with me forever. Dr. Robert Statnick (ClearSkies Consulting) and Mr. Dan Connell (CONSOL Energy R&D) provided great insight from their vast industrial experience, through our many discussions, conference calls, and collaborative efforts that I was a part of. I am thankful for the contributions of Mr. Bob Brown in an advisory capacity for the development of the calcium study funded the Ohio Coal Development Office (OCDO). I would like to gratefully acknowledge Mr. Joe Eutizi (San Miguel Electric Cooperative Inc.) and Mr. David Martin (Walnut Creek Mining Company) for providing the lignite coal samples, and Mr. Daniel Wilson (CONSOL Energy R&D) for help in char production from the coal samples. I am grateful for the financial support provided by projects funded through OCDO as well as the United States Department of Energy (USDOE). Special thanks to Mr. Paul Green and Mr. Michael Wilson. Their skills in the machine shop and their willingness to always help were key to the successful and timely completion of many of my lab scale studies. I must mention Dr. Carlo Scaccia, under whose guidance I completed my teaching assignments as a part of my doctoral studies. I learnt a great deal about professional ethics and maintaining good professional relationships from him. Angela Bennett, Lynn Flanagan, and Susan Tesfai of the CBE department always provided professional and timely assistance in all my administrative tasks. I greatly appreciate all their help. vii Special thanks to my extended family, your love keeps me strong even from halfway across the world. My friends near and far, who are always ready to lend me a patient hearing, or provide good counsel when I need it. Last but most importantly, I want to mention my family, my parents Ashwini and Rajendra, who have supported me unconditionally in every endeavor, who are my biggest pillars of strength and support. They are shiny examples of a purposeful life well-lived, I aspire to be like them every day. Also, my fiancé, Harshavardhan, who is my rock. Your love uplifts and inspires me. viii Vita June 2003 ...........................S.S.C., Balmohan Vidyamandir June 2005 ...............................H.S.C., Mumbai University June 2009 ...............................B. Chem., Mumbai University, Institute of Chemical Technology Sept 2009 to present ..............Graduate Research Associate, Department of Chemical and Biomolecular Engineering, The Ohio State University Publications Deshpande, N.; Majumder, A.; Qin, L.; Fan, L.-S. High-Pressure Redox Behavior of Iron-Oxide-Based Oxygen Carriers for Syngas Generation from Methane. Energy Fuels 2015.