Effect of different templating agents driving the synthesis of porous silicates.

In the present Master Thesis work, the influence of different templating agents, used as the basis for the synthesis of porous silicates on their final structure has been studied. Porous silicates (and especially zeolites) are playing an important role in numerous applications such as adsorption, separation, and most importantly catalysis, due to their high surface area, shape selectivity, and hydrothermal stability. In recent years, many attempts have been made to improve zeolite properties in order to enhance their performance in each of these fields. The main obstacle to overcome is the diffusion limitations induced by the presence of only micropores which can be surpassed by introducing additional porosity levels. During the Master Thesis experience, several sets of porous silicates have been synthesized using the commercial CTABr, CTAOH, Triton X-100, and Pluronic 123 as mesoporosity templates with the aim of obtaining hierarchically structured zeolites. A variation of synthesis parameters has been performed in order to achieve this goal. Then, starting from the most promising synthesis routes, the insertion of Ti atoms has been attempted, with the aim of obtaining hierarchically structured titanium silicalite (TS-1) zeolites. In this stage, great attention has been paid to ensure tetrahedral insertion of Ti inside the framework, since the incorrect incorporation can lead to the formation of non-active sites as well as titania (TiO2), which drastically reduces the catalytic activity of the resulting material. Subsequently, all the materials were characterized by means of a multi-technique approach in order to have an overview of the obtained structures and their resulting properties.