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Synthesis and Characterization of Support-Modified Nanoparticle- Based Catalysts and Mixed Oxide Catalysts for Low Temperature CO Oxidation

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Synthesis and Characterization of Support-Modified Nanoparticle- Based Catalysts and Mixed Oxide Catalysts for Low Temperature CO Oxidation University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2015 Synthesis and Characterization of Support-Modified Nanoparticle- Based Catalysts and Mixed Oxide Catalysts for Low Temperature CO Oxidation Andrew Justin Binder University of Tennessee - Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Inorganic Chemistry Commons, and the Materials Chemistry Commons Recommended Citation Binder, Andrew Justin, "Synthesis and Characterization of Support-Modified Nanoparticle-Based Catalysts and Mixed Oxide Catalysts for Low Temperature CO Oxidation. " PhD diss., University of Tennessee, 2015. https://trace.tennessee.edu/utk_graddiss/3294 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Andrew Justin Binder entitled "Synthesis and Characterization of Support-Modified Nanoparticle-Based Catalysts and Mixed Oxide Catalysts for Low Temperature CO Oxidation." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Chemistry. Sheng Dai, Major Professor We have read this dissertation and recommend its acceptance: Craig E. Barnes, Alexander B. Papandrew, Bin Zhao Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Synthesis and Characterization of Support-Modified Nanoparticle-Based Catalysts and Mixed Oxide Catalysts for Low Temperature CO Oxidation A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Andrew Justin Binder May 2015 Copyright © 2014 by Andrew J. Binder. All rights reserved. ii DEDICATION I would like to dedicate this dissertation to my parents, Glenn Binder and Dawn M. Fultz. Their perseverance and hard work, even in tough times, will always be a constant inspiration to me. iii ACKNOWLEDGEMENTS It would be impossible to complete such an arduous task as this without the help and support of many people, and quite a few have been instrumental in this work. Firstly, I would like to thank my advisor Dr. Sheng Dai for his support and guidance throughout the last 4 years. He truly cares for the success of his students and works very hard to create opportunities for myself and other members of the group. I would also like to thank the other members of my doctoral committee, Dr. Craig Barnes, Dr. Alexander Papandrew, and Dr. Bin Zhao who have pushed me at each stage of the process to think more deeply about my work and who have always been a fantastic source of advice and discussion. Here I would also like to thank Dr. Jon Camden for supporting me and pushing me to apply for graduate school at a time when I was unsure of my abilities as a scientist. Next I would like to thank all the members of the Dai group and those at the National Transportation Research Center for their hard work and assistance in learning the wide array of synthesis techniques and characterization tools needed to complete this work. In particular, from the Dai group, I would like to mention Surree Brown, Richard Mayes, Shannon Mahurin, Zhen-an Qiao, and my fellow soon- to-be-graduate Kimberly Nelson. And from NTRC: Jim Parks II, Todd Toops, Josh Pihl, and Will Brookshear. Thank you all for many various and invaluable moments of inspiration, technical help, mentoring, friendship, and professional discussion which has shaped who I am as a student and a researcher. iv Lastly, and on a personal level, I need to thank the following friends for their hilarity, emotional support, and general awesomeness: Cole and Sydney Lindsey, and Christopher Laidlaw – Long live the Starbucks crew! Tyler Newman, Matt Deaver, and Anthony Deaver – May all your rolls be Nat 20s (unless I am GM). Christopher and Chelsea Talbert, and Daniel Lester – My oldest friends and the best anyone could have. Thanks for always being there. v ABSTRACT Heterogeneous catalysts are responsible for billions of dollars of industrial output and have a profound, if often understated, effect on our everyday lives. New catalyst technologies and methods to enhance existing catalysts are essential to meeting consumer demands and overcoming environmental concerns. This dissertation focuses on the development of catalysts for low temperature carbon monoxide oxidation. CO [carbon monoxide] oxidation is often used as a probe reaction to test overall oxidation activity of a given catalyst and is an important reaction in the elimination of toxic pollutants from automotive exhaust streams. The work included here presents three new heterogeneous catalysts developed over the last 4 years in our group. The first type Au/SiO2 [gold/silica] catalyst synthesized using a new method for the deposition of Au nanoparticles onto SiO2 via a nitrogen-containing polymer, C3N4 [carbon nitride]. C3N4-modification of SiO2 allows us to ignore unfavorable electrostatic effects that hinder standard Au deposition onto this support. While removal of the C3N4 is necessary for good CO oxidation, this new method is an improvement over the standard deposition-precipitation procedure for supports with low isoelectric point that enables the successful deposition of Au nanoparticles onto SiO2. The second type includes precious metal catalysts deposited on an “inert” silica support but promoted by the addition of an “active” metal oxide. Here we vi present a Au/FeOx/SiO2 [gold/iron oxide/silica] and a Pd/ZrO2/SiO2 [palladium/zirconia/silica] catalyst which show increased activity and stability effects due to the presence of the metal oxide promoter. They are synthesized by a C3N4-deposition and sol-gel methods, respectively. These catalysts were also tested in simulated automotive exhaust streams. The results show that inhibition effects play a major role in the activity of these catalysts. The third type of catalyst is a mixed oxide catalyst, CuO-Co3O4-CeO2 [copper oxide-cobalt oxide-cerium oxide], developed with the goal of overcoming the inhibition effects seen in the previous precious metal catalysts. The catalyst was synthesized by co-precipitation method and shows exceptional activity for CO oxidation under simulated exhaust conditions. Also noteworthy is the observation that this catalyst also shows a lack of inhibition by a common exhaust component, propene. vii TABLE OF CONTENTS CHAPTER 1 -- INTRODUCTION AND BACKGROUND ................................................................... 1 1.1 INTRODUCTION TO CATALYSIS ........................................................................................................................ 1 1.1.1 Introduction ................................................................................................................................................. 1 1.1.2 Heterogeneous Catalysis ......................................................................................................................... 4 1.1 CO OXIDATION ................................................................................................................................................... 8 1.1.1 CO Oxidation over Supported Noble Metal Nanoparticles ...................................................... 8 1.1.2 Size dependency of Supported Metal Nanoparticles .................................................................. 9 1.1.3 CO Oxidation over Transition Metal Oxides ................................................................................ 10 1.1.4 Mechanisms for CO Oxidation ........................................................................................................... 11 1.2 MOTIVATION .................................................................................................................................................... 14 1.2.1 Deposition and Stabilization of Au Nanoparticles ................................................................... 14 1.2.2 Automotive Exhaust Treatment ....................................................................................................... 16 1.3 COMMON CATALYST SYNTHETIC TECHNIQUES ......................................................................................... 18 1.4 DISSERTATION OVERVIEW ............................................................................................................................ 24 CHAPTER 2 -- CHARACTERIZATION TECHNIQUES ................................................................... 27 2.1 CATALYST CHARACTERIZATION ................................................................................................................... 27 2.1.1 Scanning Transmission Electron Microscopy (STEM) ............................................................ 27 2.1.2 Powder X-Ray Diffraction (PXRD) ................................................................................................... 30 2.1.3 N2 Adsorption/Desorption (BET) ..................................................................................................... 32 2.1.4 Infrared Spectroscopy (FTIR and DRIFTS) .................................................................................
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