Application of Solid State NMR for the Study of Surface Bound Species and Fossil Fuels Stacey Marie Althaus Iowa State University
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Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2014 Application of solid state NMR for the study of surface bound species and fossil fuels Stacey Marie Althaus Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Analytical Chemistry Commons, Nanoscience and Nanotechnology Commons, Other Chemistry Commons, and the Physical Chemistry Commons Recommended Citation Althaus, Stacey Marie, "Application of solid state NMR for the study of surface bound species and fossil fuels" (2014). Graduate Theses and Dissertations. 14111. https://lib.dr.iastate.edu/etd/14111 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Application of solid state NMR for the study of surface bound species and fossil fuels by Stacey Althaus A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Physical Chemistry Specialization: Instrumentation Program of Study Committee: Marek Pruski, Co-major Professor Aaron Sadow, Co-major Professor Igor Slowing Theresa Windus Wenyu Huang Iowa State University Ames, Iowa 2014 Copyright © Stacey Althaus, 2014. All rights reserved. ii TABLE OF CONTENTS ACKNOWDLEGEMENTS .......................................................................................... vi CHAPTER 1. INTRODUCTION ...................................................................................1 General NMR ...................................................................................................................1 Vector Model ....................................................................................................................2 Net Magnetization ........................................................................................................2 Precession .....................................................................................................................3 Radiofrequency Pulses in Vector Model ......................................................................4 The Quantum Mechanics of NMR ...................................................................................5 The Nuclear Spin Hamiltonian .....................................................................................5 The Zeeman Interaction .........................................................................................6 Chemical Shift Shielding ........................................................................................6 Dipolar Coupling ....................................................................................................9 J-Coupling .............................................................................................................10 Quadrupolar Coupling ..........................................................................................11 Radiofrequency Pulse ................................................................................................11 Magic Angle Spinning (MAS) .......................................................................................12 Mathematical Representations ...................................................................................12 Advantages of Fast MAS ...........................................................................................13 Methods ..........................................................................................................................15 Cross-Polarization (CP) ..............................................................................................15 INEPT ........................................................................................................................17 Indirect Detection ......................................................................................................18 References ......................................................................................................................19 iii CHAPTER 2. SOLID-STATE NMR STUDIES OF FOSSIL FUELS USING ONE- AND TWO-DIMENSIONAL METHODS AT HIGH MAGNETIC FIELD ...........................................................................................................................22 Abstract ..........................................................................................................................22 Introduction ....................................................................................................................23 Experimental Section .....................................................................................................25 Coals ...........................................................................................................................25 NMR Measurements ...................................................................................................26 Results and Discussion ...................................................................................................27 Sensitivity, Resolution, and CP Efficiency Under Fast MAS ....................................27 Quantification .............................................................................................................32 Two-Dimensional Analysis ........................................................................................37 Conclusion ......................................................................................................................43 Acknowledgements .......................................................................................................44 References ......................................................................................................................44 CHAPTER 3. INDIRECTLY DETECTED HETERONUCLEAR CORRELATION SOLID-STATE NMR SPECTROSCOPY OF NATURALLY ABUNDANT 15N NUCLEI ................................................................48 Abstract ..........................................................................................................................48 Introduction ....................................................................................................................49 Experimental Section .....................................................................................................52 Sample Preparation .....................................................................................................52 NMR Measurements and Numerical Simulations ......................................................52 Results and Discussion ...................................................................................................54 2D 1H{15N} Spectra of MLF, Histidine and PUP-MSN ...........................................54 Sensitivity Gain ..........................................................................................................58 Numerical Simulations of INEPTR transfer ..............................................................60 Conclusion ......................................................................................................................62 Acknowledgements .......................................................................................................63 iv References ......................................................................................................................63 Supporting Information ..................................................................................................68 Measurement of J-resolved Spectra ............................................................................68 Comparison of Probe Sensitivity in 13C DPMAS and CPMAS Measurements on Hexamethylbenzene (HMB) .......................................................................................68 Signal Intensity During INEPTR Transfer .................................................................69 References ......................................................................................................................69 CHAPTER 4. ALDOL CONDENSATION IN HETEROGENOUS CATALYSIS: A MECHANISTIC STUDY ...............................................................77 Abstract ..........................................................................................................................77 Introduction ....................................................................................................................78 Experimental ..................................................................................................................79 Samples.......................................................................................................................79 Materials ................................................................................................................80 Synthesis of Smaller Pore MSNs ...........................................................................80 Synthesis of Larger Pore MSNs ............................................................................81 Silylation ................................................................................................................81 Aldol Condensation Reaction .....................................................................................81