| As a bulk component in catalytic system, solvent is of indisputable importance to molecular conformation, electron properties and reaction process etc. Therefore, an all-around understanding of solvent effect in the Titanium Silicalite/H2O2makes it easier and more efficient to optimize solvent for catalytic systems, while delivers tremendous economic and environmental effect.However, although researchers can reasonably explain the experimental observation, the nature of solvent effect still remains unknown. This dissertation is aimed to unveil the chemical nature of solvent effect through insights into the following aspects:(1) structure and properties of titanosilicalites catalysts;(2) properties of solvents;(3) interaction of additive (eg. ammonia) with reactant, solvent, and active intermediate.The results of this paper show that, the structure and properties of Titanosilicalites have obvious effect on the solvent effect of these catalytic systems. TS-1and Ti-MWW, which have different framework structures led to different favorable solvent. Particle size of titanosilicalites can also contribute to solvent effect for different density of OH-on the surface caused by different particle size.To further unveil the chemical nature of the volcano curve caused by addition of ammonia into catalytic systems, this paper measured and calculated Activation Energy for each catalytic system. It was found that, as the amount of ammonia added into catalytic system increases, activation energy decreases. Therefore, we preclude that there must be a certain interaction between ammonia and components in the catalytic systems:lone electron pair on N atom in ammonia interacts with H on the active intermediate through Hydrogen Bonding. Therefore, the active intermediate is stabilized by ammonia, leading to higher catalytic activity.To sum up, the active intermediate would go through the following three steps:formation, stabilization, decomposition, accompanying with solvent effect in this whole process. |
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