Extensive consumption of carbon resources has led to decreasing reserves of fossil fuels and growing concern about global warming. This dilemma has promoted a shift in the economy to develop new long-term, environmentally friendly, and sustainable sources for fuels and chemicals to replace fossil fuel-based sources. Renewable biomass is an ideal alternative, as it is abundant, and relatively cheap. Among current biofuel resources, 5-hydroxymethylfurfural (5-HMF) is a versatile intermediate between biomass-based carbohydrate chemistry and fossil fuel-based industrial organic chemistry, which can be used to synthesize a broad range of chemicals that are currently derived from fossil fuel-based resources. Carbohydrates became the preferred feedstock for high yield production of 5-HMF, and the most convenient route for the synthesis of 5-HMF is the acid-catalyzed dehydration of hexose. Within this context, a variety of processes were developed for the synthesis of 5-HMF from dehydration of fructose involving various solvents, including water, organic solvents, and biphasic systems. Likewise, a range of catalysts were employed, such as homogeneous acid catalysts and metal chlorides, which showed high catalytic activity. Heterogeneous catalysts have also been receiving attention due to their advantages such as easy recovery and recyclability. In the current research, microwave-assisted synthesis of 5-HMF by dehydration of fructose over various acidic porous catalysts, such as periodic mesoporous organosilica (PMO), carbon materials, and metal organic frameworks (MOFs), was investigated. The results showed that the obtained 5-HMF yields were satisfactory, and more importantly highlighted some of the properties of porous heterogeneous catalysts that may improve the production of 5-HMF.

Glycerol and fructose are molecules that are readily available in substantial quantities fromthe biomass. In this work dehydration routes for valorization of these compounds wereinvestigated. Therefore, zirconia and titania based catalysts, and calcium phosphate materialswere prepared and evaluated in the glycerol dehydration in gas phase. Niobia-ceria mixedoxides and mesoporous Nb2O5-MeO2 (M = Ce, Zr, Ti) mixed oxides were prepared andtested in fructose dehydration reaction in aqueous phase. The surface acid-base properties ofthe studied catalysts were correlated to their catalytic performance.

Le glycérol et le fructose sont des molécules qui peuvent être extraites facilement de labiomasse et en des quantités substantielles. Ce travail de recherche porte sur la déshydratationcomme moyen de valoriser ces composés. C’est dans ce but que des catalyseurs supportés suroxydes de zirconium et de titane, ainsi que des matériaux de type phosphate de calcium, ontété préparés et testés pour la réaction de déshydratation du glycérol en phase gazeuse. Desoxydes mixtes de niobium et cerium ainsi que des oxydes mixtes mésoporeux de Nb2O5-MeO2 (M = Ce, Zr, Ti) ont été également préparés et cette fois-ci testés pour la réaction dedéshydratation du fructose en milieu aqueux. Dans les deux cas, les propriétés acido-basiquesde surface des catalyseurs étudiés ont été corrélées à leur efficacité catalytique. / Glycerol and fructose are molecules that are readily available in substantial quantities fromthe biomass. In this work dehydration routes for valorization of these compounds wereinvestigated. Therefore, zirconia and titania based catalysts, and calcium phosphate materialswere prepared and evaluated in the glycerol dehydration in gas phase. Niobia-ceria mixedoxides and mesoporous Nb2O5-MeO2 (M = Ce, Zr, Ti) mixed oxides were prepared andtested in fructose dehydration reaction in aqueous phase. The surface acid-base properties ofthe studied catalysts were correlated to their catalytic performance.