A Density Functional Study of the Chemical Differences between Type I and Type II MoS2-Based Structures in Hydrotreating Catalysts
Citations Over TimeTop 1% of 2004 papers
Abstract
Density functional theory is used to investigate the origin of the activity differences between Type I and Type II MoS2-based structures in hydrotreating catalysts. It is well known that the Type II structures, where only weak interactions with the support exist, have a higher catalytic activity than Type I structures, where Mo-O linkages to the alumina are present. The present results show that the differences in activities for MoS2 and Co-Mo-S structures can be attributed to the electronic and bonding differences introduced by the bridging O bonds. We find that the Mo-O linkages are most probably located on the (1010) S edge. The presence of oxygen linkages increases the energy required to form sulfur vacancies significantly so that almost no vacancies can be formed at these and neighboring sites. In this way, the reactivity of the S edge is reduced. In addition, the studies also show that the linkages introduce changes in the one-dimensional metallic-like brim states. Furthermore, the presence of oxygen linkages also changes the energetics of hydrogen adsorption, which becomes less exothermic on sulfur sites directly above linkages and more exothermic on sulfur sites adjacent to linkages. The present results explain previously observed differences in Type I-Type II transition temperatures for Co-Mo-S structures with different Co contents.
Related Papers
- → A Parallel Colorimetric Method for the Rapid Discovery and Optimization of Heterogeneous Hydrodesulfurization Catalysts(2003)16 cited
- → Catalytic activity of NiMo/TiO2−Al2O3 systems in thiophene hydrodesulfurization(1995)11 cited
- → In Situ Radioisotopic Study of the Active Sites of Sulfide CoMo Catalysts and the Mechanism of Thiophene Hydrodesulfurization(2003)10 cited
- → Human Energetics(2012)16 cited
- Study on impact of H_2S on diesel hydrodesulfurization(2012)