Synthèse de matériaux mésoporeux bi-fonctionnalisés pour des applications catalytiques

Abstract

The conversion of carbon dioxide is attracting the rising interest of the scientific community due to the possibility to transform a waste into useful chemicals. The reaction between CO2 and epoxides may lead to the synthesis of highly demanded products such as the cyclic carbonates, which can find applications as aprotic polar solvent, as electrolyte in the manufacture of battery and as precursors of polycarbonates. Various homogeneous or heterogeneous catalysts were already developed for this reaction. Among those, imidazolium salts display excellent catalytic activity. However high temperature are usually required to get a good conversion. An efficient way to decrease the reaction temperature while preserving good CO2 conversions is represented by the use of co-catalysts (usually Lewis acid centres). Recently, we proved that the insertion of Zn and Sn as single site within the silica framework followed by the post-functionalization with imidazolium salts allow obtaining a bi-functional catalyst with improved performances. Here, we explored the insertion of titanium in the silica architecture as Lewis acid centre to favour the ring opening of the epoxides. Moreover, it is known that titanium based catalysts (e.g. Ti-MCM-41 and Ti-SBA-15) display high catalytic activity for the epoxidation of alkene. Therefore, it should be possible to form the cyclic carbonates from their corresponding alkene using a titanium-based catalyst functionalized with imidazolium salts. The objective of this master thesis is to synthesize bi-functional mesoporous materials bearing titanium as single site in the silica structure and decorated with imidazolium salts. Two supports will be compared, MCM-41 like and the SBA-15 like structures. All the materials were fully characterised in terms of textural, structural and catalytic properties. The solids were used in oxidation of an alkene into epoxide and the conversion of this epoxide into the corresponding cyclic carbonate.

Date of Award	Sept 2019
Original language	French
Awarding Institution	University of Namur
Supervisor	Carmela Aprile (Supervisor)