Catalytic Hydrogenation Of Carbon Monoxide

Author : Andrew J. Medford
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (919 download)

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Download or read book Computational Insight Into Catalytic Hydrogenation of Nitrogen and Carbon Monoxide written by Andrew J. Medford and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational modeling is becoming an increasingly important tool in the design of heterogeneous catalysts. This thesis explores recent advances in the atomic-scale computational design of catalytic materials. Nitrogen hydrogenation is used to illustrate the core concepts in part I, and these concepts are applied to a wide range of carbon monoxide hydrogenation reactions in part II. Nitrogen hydrogenation, or ammonia synthesis, is one of the most important catalytic processes ever discovered. Industrial-scale ammonia synthesis enabled the mass production of fertilizers which are now used to produce approximately half of the global food supply. Ammonia synthesis is also a well-studied and relatively simple catalytic reaction, and has served as a bellwether reaction for computation in heterogeneous catalysis. Part I of this thesis revisits the ammonia synthesis reaction. Chapter 2 discusses the importance of ammonia synthesis and heterogeneous catalysis in general. Chapter 3 introduces density functional theory (DFT), the workhorse method in quantum-mechanical studies of catalytic materials. Chapter 4 examines how DFT energies can be combined with kinetic modeling in order to gain insight into catalytic trends and design strategies for ammonia synthesis. Chapter 5 applies a novel method for uncertainty quantification and error propagation in order to demonstrate the robustness of the computational catalyst design against uncertainty in the DFT calculations. Hydrogenation of carbon monoxide (CO) is a complex process with many potentially valuable products including methane, methanol, and higher hydrocarbons and alcohols. These reactions will play an increasingly important role in the global economy as fossil resources are exhausted and replaced by more sustainable synthetic fuels. Part II of the thesis applies many of the concepts introduced in part I to CO hydrogenation reactions. Chapter 6 examines the production of ethanol from synthesis gas (CO and H2) and applies the techniques of chapter 4 in order to map the activity and selectivity trends across transition-metal (211) surfaces. Several alloys are identified as promising catalysts for selective ethanol synthesis, including CoCu and CoPt alloys. Chapter 7 combines computational methods and experiments to provide insight into the complex selectivity patterns of CO hydrogenation over rhodium catalysts, indicating that the reaction is structure sensitive and that rhodium catalysts are intrinsically selective toward acetaldehyde rather than ethanol. Chapter 8 and chapter 9 examine CO hydrogenation over non-metallic catalysts (Mo2C and ZnO), revealing the importance of surface termination and the fundamentally different surface reactivity of transition-metal compounds.