FAU zeolites with varied porosities and chemical compositions as catalysts for reactions in immiscible liquid-liquid systems

Abstract

In this project, acid catalysts based on the FAU structure will be used. These zeolites present adjustable micro-mesoporosity and variations of the hydrophobic-hydrophilic balance depending on their chemical composition. In a few two-phase reaction systems, the issue of phase immiscibility can be a problem for the overall performance of the process, so the choice of catalysts that favor phase contact is of great importance. The FAU structure zeolites are strong candidates for reactions in immiscible two-phase systems, which we will verify in the ketalization reaction of glycerol with ketones. The motivation lies in the production of biodiesel, which is obtained from the transesterification reaction (triacylglycerol + alcohol ’ alkyl ester (biodiesel) + glycerol). In this reaction, about 10% by mass of glycerol is co-produced. A strategy to enhance this process is to use glycerol to produce solketal ((2,2-dimethyl-1,3-dioxolan-4-yl)methanol), from the catalytic reaction of ketalization of glycerol with acetone, which, in turn, can be obtained from hemicellulose products. However, the ketalization reaction takes place in a two-phase liquid-liquid system, and one of the ways to improve the overall performance of the process is by using solvents to increase the solubility/miscibility of the reactants. In line with green chemistry, a solvent-free route is better, as it increases the complexity of the reaction system and requires additional steps for recovery and recycling. For these systems, zeolites are of special interest, as they can present hydrophobic-hydrophilic surfaces and have a pore structure that can be favorable to conduct reactions with bulky molecules.