Study On The Reaction Of Several Atoms Clusters With Small Molecules

The rational design of new catalysts with high activity and selectivity is very important.Compared with the complexity of the actual catalytic system,clusters can be used as an ideal model to understand the reaction mechanism at the molecular level.In this thesis,the reaction activity of the corresponding clusters is measured by gas mass spectrometry experiments,and the microscopic mechanism is analyzed by theoretical calculations.The specific research contents are as follows:Based on the experiments of mass spectrometry and theoretical analysis of DFT,the diatomic clusters Au2+,AuRh+ and Rh2+ cation clusters were compared.It is found that the doped cluster AuRh+has moderate reactivity,but it can generate carbene AuRh-CH2+and release H2,avoiding excessive dehydrogenation of CH4 like Rh2+.Our results indicate that the presence of Rh is a factor of high reactivity,while Au leads to high selectivity,and this phenomenon is further understood through the unique inherent bonding properties of metals.Research on the reaction of doped metals to methane provides a promising method for finding the most suitable way to directly convert methane into value-added chemicals.In addition,studying the reaction of transition metal oxide clusters with carbon monoxide in the gas phase can not only have a similar effect to the catalytic behavior of condensed phase oxides,but also explain the transition metal oxide clusters at a strict molecular level.How the clusters behave as a catalyst for carbon monoxide can reveal the active sites and reaction mechanism of the condensed phase catalytic system at the molecular level,and provide a theoretical basis for rational design and improvement of catalysts.In this paper,even when the size of titanium dioxide anion cluster(TiO2)nOm-is enlarged to n=60,(TiO2)nO-still has a higher ability to oxidize carbon monoxide than other clusters(TiO2)nOm-(m ≠1).This indicates that each atom affects the overall chemical properties of titanium dioxide.It Provides compelling molecular-level evidence for the Mars-van Krevelen mechanism for CO oxidation on titanium dioxide supports.