An investigation of MoP catalysts for alcohol synthesis
| Autor: | Zaman, Sharif Fakhruz |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Druh dokumentu: | Text |
| Popis: | Molecular simulation and experimental methods have been used to assess the catalytic behavior of MoP in the conversion of synthesis gas (CO, CO₂, H₂) to oxygenated hydrocarbons. The potential energy surface of synthesis gas conversion to methane and methanol was investigated on a Mo₆P₃ cluster model of the MoP catalyst. The potential energy surface (PES) for CH₄ formation was determined to be: COad → CHOad → CH₂Oad → CH₂OHad → CH₂.ad+H₂Oad → CH₃.ad+H₂Oad → CH₄+H₂O and for CH₃OH : COad → CHOad → CH₂Oad → CH₂OHad → CH₃OHad. The hydroxymethyl (CH₂OH) species was a common reaction intermediate for both CH₄ and CH₃OH formation and the simulation predicted selective formation of CH₄ rather than CH₃OH from syngas over MoP. The cluster model was modified to investigate the effect of a SiO₂ support and a K promoter. Both SiO₂ and K decreased the activation energy for methanol formation. However, the activation energy for methanol formation remained higher than the activation energy for C-O bond cleavage. The high adsorption energy of methanol and the formation of geminal dicarbonyl species on the K-Mo₆P₃-Si₃O₉ cluster suggested the possibility of the formation of higher oxygenates. The conversion of syngas to alcohols was also investigated on 5, 10, and 15 wt% MoP supported on silica, with 0, 1, and 5 wt% K added as a promoter The major products were acetaldehyde, acetone and ethanol. Low selectivities to methanol Applied Science, Faculty of Chemical and Biological Engineering, Department of Graduate |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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