Investigation of Mechanism for Fischer-Tropsch Synthesis by Density Functional Theory and Kinetic Monte Carlo Method
| Autor: | Lu, Chun-Yu, 盧俊宇 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 This thesis is focused on mechanistic study of Fischer-Tropsch(F-T) synthesis reaction on Ru(0001) and Co(0001) surfaces by density functional theory(DFT) and kinetic Monte Carlo (kMC) method. DFT was employed to optimize the local minima and transition states for a series of elementary steps in the formation of C1 (CH4) and C2 (C2H4 and C2H6) products from reactants of CO and H2. The resulted energetics, including adsorption energy and activation barriers, were applied for kMC simulation to reveal the mechanism and product selectivities. The computations found that the first step in F-T is CO hydrogenation in the formation of CHO on both Ru(0001) and Co(0001) surfaces. CHO could further hydrogenated to CH2O or CH3O before the C-O bond breaking forming CHx on Co(0001) surface. The resulted CHx has better chance for hydrogenation to CH4. On the other hand, CHO immediately breaks its C-O bond forming CH on Ru(0001) surface. The intermediates favors C-C coupling reaction and forming C2 products. Thus, hydrogenation or C-O bond dissociation of CHO are the key step to control C1 and C2 product selectivity. In the temperature effect study, both surfaces have more C2 products at higher temperature. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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