Date of Award

1-1-2013

Document Type

Open Access Thesis

Department

Chemical Engineering

First Advisor

John R Regalbuto

Abstract

The purpose of this thesis is to study the effect of nano-particle size, support and potassium dopant on ruthenium activity on the levulinic acid (LA) hydrogenation to ã-valeroactone (GVL).In hydrogenation reaction, H2 as the gas phase reactant reacts with the metal atoms at the surface of particle size, thus a high level of metal dispersion is critical to maximize the amount of atoms on the surface. This reaction has been widely investigated by varied metal supported catalysts and proved that Ru is the most active metal for it. However, most of researchers only focused on the reaction pathway, rather than the Ru particle size. Furthermore, Ru particle size synthesis by varies methods for other types of reactions also have been reported, even the same method, metal precursor and metal weight loading were employed, but the same Ru particle size could not be obtained. Due to the important role of the metal particle size, it needs to be systematically examined.

Chapter 1 provides a brief introduction to explain why the purposes and importance of this research. Important theoretical concepts and description are illustrated about the reaction pathway, the preparation method of catalyst and the used characterization techniques (ICP, TPR, XPS, XRD, STEM and Chemisorption). A literature review is also listed there.

The experimental operation is described in Chapter 2. The catalysts prepared by strong electrostatic adsorption and dry impregnation as well as commercial catalysts were used for kinetic evaluation. Ru metal deposited on low PZC support: oxidized carbon and high PZC support: ã-Al2O3. TPR is used to determine the proper reduction temperature. After H2 reduction pretreatment, Ru particle size was characterized by XRD, STEM and chemisorptions.

The results and discussion are thoroughly explained in Chapter 3.The particle size obtained by XRD, STEM and Chemisorption for both supports has a good agreement that the metal dispersion order: SEA >DI>commercial catalyst and the catalytic activity also follows the same order. In addition, carbon show higher activity than ã-Al2O3. Due to the addition of K, the catalytic activity is enhanced significantly.

The general conclusions for these results are presented in Chapter 4 together with recommendation for future work. In this work, 3% K was doped to the selected catalysts, which show significant increased activity. However, the maximum amount of K promoting this reaction will be studied because too much K doped may block the active sites, which leads to inhibit this reaction. In addition, bimetallic RuRe prepared by Co-SEA and Co-DI will be evaluated and compare with monometallic catalysts.

Rights

© 2013, Shuo Cao

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