University of Massachusetts Amherst ScholarWorks@UMass Amherst Doctoral Dissertations Dissertations and Theses March 2019 Synthesis and Molecular Transport Studies in Zeolites and Nanoporous Membranes Vivek Vattipalli University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/dissertations_2 Part of the Catalysis and Reaction Engineering Commons, Inorganic Chemistry Commons, Materials Chemistry Commons, Membrane Science Commons, Other Materials Science and Engineering Commons, and the Transport Phenomena Commons Recommended Citation Vattipalli, Vivek, "Synthesis and Molecular Transport Studies in Zeolites and Nanoporous Membranes" (2019). Doctoral Dissertations. 1525. https://doi.org/10.7275/13141751 https://scholarworks.umass.edu/dissertations_2/1525 This Open Access Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. SYNTHESIS AND MOLECULAR TRANSPORT STUDIES IN ZEOLITES AND NANOPOROUS MEMBRANES A Dissertation Presented by VIVEK VATTIPALLI Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY February 2019 Department of Chemical Engineering i © Copyright by Vivek Vattipalli 2019 All Rights Reserved ii SYNTHESIS AND MOLECULAR TRANSPORT STUDIES IN ZEOLITES AND NANOPOROUS MEMBRANES A Dissertation Presented by VIVEK VATTIPALLI Approved as to style and content by: __________________________ Wei Fan, Chair __________________________ Peter Monson, Member __________________________ Friederike Jentoft, Member __________________________ Zhiping Lai, Member __________________________ Ashwin Ramasubramaniam, Outside Member __________________________________ John Klier, Head, Department of Chemical Engineering, University of Massachusetts Amherst iii ACKNOWLEDGEMENTS This work was supported by the National Science Foundation through Grant Number CBET 1403542, as well as by the Catalysis Center for Energy Innovation, an Energy Frontier Research Center (Award DE-SC0001004) funded by the US Department of Energy, Office of Science and Office of Basic Energy Sciences. I would like to express my very great appreciation to my research advisor, Prof Wei Fan for his patient guidance, encouragement and mentorship throughout the duration of my PhD. I would like to thank him in particular for giving me the freedom to try out new ideas right from the beginning of my PhD, and for helping me develop confidence in my own abilities as a researcher. I also thank our collaborators, Prof Peter Monson, Prof David Ford and Dr Ashutosh Rathi for fruitful and illuminating discussions as part of the work on fundamental transport studies. I really enjoyed being part of such a collaborative research team. I am grateful to have Prof Peter Monson, Prof Friederike Jentoft, Prof Zhiping Lai and Prof Ashwin Ramasubramaniam as part of my committee. Their advice and suggestions have enriched my research work. I also thank Prof Paul Dauenhauer, Prof Andrew Teixeira and Xiaoduo Qi for useful advice and discussions during the zeolites diffusion work. I am fortunate to have been able to conduct my research work alongside great lab members – Dr Chun-Chih Chang, Dr Paul Dornath, Dr Hong Je Cho, Prof Chao Li, Xiaoduo Qi, Sanket Sabnis, Prof Zhengyan Zhao, Prof Junliang Wu, Prof Jinsheng Guo, Jason Gulbinski, Prof Huiyong Chen, Prof Yongfei Li, Dr Qiaozhi Ma, Qiyu Liu and Kaivalya Gawande. I want to thank various undergraduate researchers who worked with me – Michael Stellato, Sydney Foster, Abdul Mughis Paracha and Li Zhang. It has been a pleasure working with all of you and learning together from each others’ experiences. I also want to thank Dr Alexander Ribbe and Louis Raboin at the UMass Electron Microscopy Center and Dr Weiguo Hu at the UMass NMR Labs. They helped me learn the proper theory and ways to use different instruments and were always available for help with specific characterization issues. Their efforts in effectively managing the instrument facilities are greatly appreciated. I thank all the friends I have made while at UMass – Ashutosh, Ishan, Satyan, Ray, Alyssa, Raghu, Saurabh, Kristeen, Ashish, Özge, Keri, Katie, Dan, Elizabeth, Nancy and iv Liz, as well as the rest of ChEGS, for the great memories we have had together throughout our time here. I hope we can continue to be in touch as we embark on our new journeys. I would also thank the chemical engineering staff – Marie, Amity, Anshalee, Jessica, Joe and Gary, for helping make our time here smooth and letting us concentrate on the academics. Lastly, I would like to thank my family. My parents, sister and brother-in-law have been a constant source of support throughout my time at UMass. Finally, my wife, Sahithi, who has been my pillar through the last part of my PhD. I appreciate her constant love and support through everything. v ABSTRACT SYNTHESIS AND MOLECULAR TRANSPORT STUDIES IN ZEOLITES AND NANOPOROUS MEMBRANES FEBRUARY 2019 Vivek Vattipalli, B.Tech., Indian Institute of Technology Madras M.Tech., Indian Institute of Technology Madras Ph.D., University of Massachusetts Amherst Directed by: Professor Wei Fan The advent of nanoporous materials such as zeolites and nanoporous membranes has provided cost-effective solutions to some of the most pressing problems of the 20 th century such as the conversion of crude oil into fuels and valuable chemicals. Hierarchical zeolites and mesoporous inorganic membranes are showing great promise in addressing new problems such as the conversion of biomass into value-added chemicals and development of energy-efficient separation processes. The synthesis and fundamental aspects of molecular transport in these new materials with hierarchical porosities need to be better understood in order to rationally develop them for these desired applications. Pore narrowing and pore blockage have been proposed to cause the significantly slower than expected diffusion in hierarchical zeolites and zeolite nanoparticles. In the first part of this work, the diffusion of cyclohexane and 1-methylnaphthalene is studied in MCM-41, SBA-15 and conventional as well as hierarchical silicalite-1 zeolite. The role of sorbate-sorbent interactions is investigated and surface diffusion-mediated pore re-entry into micropores is proposed to cause the slower overall diffusion in these materials. Previous molecular transport studies in zeolites have been limited to the MFI zeolite framework, mainly due to ease of synthesis of siliceous MFI in comparison to other siliceous zeolites. Additionally, the requirement of fluoride for the synthesis of siliceous zeolites makes practical applications of these materials difficult. The second part of this work addresses these problems by developing a general, fluoride-free method for the vi synthesis of siliceous zeolites. The dry gel conversion (DGC) method is used to synthesize 2 new siliceous zeolites for the first time without using fluoride. Mechanistic aspects of siliceous zeolite synthesis, the DGC method in particular, are studied and employed to further improve the synthesis method. Mesoporous inorganic membranes have ideally suited properties for separations such as low pressure drop and thermal as well mechanical stability. However, two challenges impede their applications – the large-scale synthesis of defect-free mesoporous membranes and the development of a fundamental understanding of molecular transport in them. In the third part of this thesis, a new, scalable synthesis method with superior coverage is demonstrated for the synthesis of hybrid mesoporous silica-anodized aluminium oxide (AAO) membranes. Steady state non-equilibrium capillary condensation is studied in detail using the permeation of butane through AAO membranes. New aspects of this phenomenon are reported and experimental evidence is found in support of a partial capillary condensed state of a mesopore stabilized by molecular transport. vii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ............................................................................................... iv ABSTRACT .................................................................................................................... vi LIST OF TABLES ............................................................................................................. xi LIST OF FIGURES .......................................................................................................... xii CHAPTER 1. INTRODUCTION ......................................................................................................1 1.1.Synthesis and Molecular Transport in Zeolites .................................................1 1.2.Synthesis and Molecular Transport in Mesoporous Membranes .......................3 1.3.Thesis scope .......................................................................................................4 2. DIFFUSION STUDIES IN HIERARCHICAL ZEOLITES AND MESOPOROUS SILICAS ......................................................................................................................5 2.1.Background ........................................................................................................5 2.2.Experimental section ........................................................................................12