Conversion catalytique du glycérol en solketal par des gallo-silicates préparés via le procédé aérosol

Abstract

During the last decade, considerable attention has been devoted to the development of biofuels, above all biodiesel, as a promising alternative to fossil fuels. The transesterification reaction to produce biodiesel yields as by-product an amount of glycerol that represents approximately 10 wt % of the total biodiesel manufacture. With the increase of biodiesel production, glycerol is now considered as a waste and solutions for its efficient utilization are needed. A promising route is represented by the condensation of glycerol with acetone to produce solketal, an added-value product with several applications such as surfactant, flavoring agent, plastifying agent, safe solvent or in blend with biodiesel to improve its properties. A sustainable way to perform this reaction envisages the use of heterogeneous catalysts displaying Brønsted and Lewis acidities. Porous silicates presenting a metal inserted as single site in the framework can be active and selective catalysts for this reaction. In particular, it has been already reported that Ga-MCM-41 nanoparticles are one of the most efficient catalysts in the conversion of glycerol into solketal. Here, the aerosol assisted sol-gel process was used as a powerful tool to synthesize silica-based solids with Ga inserted as single-site in the structure. The influence of different parameters on both morphological properties and catalytic activity, as the Si/Ga ratio or the nature of the templating agent, were studied. Furthermore, to optimize the design of the catalysts, the role played by the hydrophobic/hydrophilic balance of the catalyst surface was investigated. The aerosol process was successfully used to synthesize a series of Ga-silicates with different degrees of methyl-functionalization using a co-synthetic one-pot approach. All the synthesized materials were fully characterized and tested for the conversion of glycerol into solketal with promising results.

Date of Award	Jun 2019
Original language	French
Awarding Institution	University of Namur
Supervisor	Carmela APRILE (Supervisor)