This dissertation addresses the surging global demand for sustainable energy alternatives and biobased products, driven by population growth and the imperative to shift away from finite fossil fuels amidst climate change. The research centers on the catalytic upgrading of rice straw bio-oil, employing bimetallic magnetic nano-catalysts on rice straw-derived biochar to align with the imperative for environmentally conscious energy solutions. In the initial phase, the study systematically explores upgrading processes using varied alcohols, specifically ethanol, and butanol, under mild conditions to enhance bio-oil quality. The detailed evaluation of catalyst composition reveals a notable reduction in oxygen content, coupled with a significant increase in energy density and calorific value. The upgraded bio-oil not only exhibits heightened stability but also undergoes a substantial shift towards a more desirable hydrocarbon-rich composition. The second part of the research optimizes upgrading process parameters catalyst concentration, reaction holding time, and reaction temperature using Response Surface Methodology based on the Box-Behnken experimental design. This optimization refines the catalytic upgrading process, enhancing its efficiency and reliability. Beyond catalytic efficacy, the study considers the magnetic recovery of catalysts for potential reuse, emphasizing sustainability on a broader scale. Set against the backdrop of global energy challenges, this research significantly contributes to advancing the understanding of bimetallic magnetic nano-catalysts. The dissertation unfolds in two parts, with the first segment focusing on Catalytic Upgrading of Rice Straw Bio-Oil via Esterification in Supercritical Ethanol Over Bimetallic Catalyst (CuO-Fe3O4/AcB), involving the variation of Cu and Fe metals on Rice Straw Biochar without hydrogen gas. The exploration continues with the Upgrading of Rice Straw Bio-Oil in Butanol and hydrogen gas Over a Sustainable Magnetic Bimetallic Nano-Catalyst (ZrO2-Fe3O4/AcB). The integrated analytical approach, utilizing XRD, SEM, FT-IR for synthesized catalysts, alongside GC-MS and the Bomb Calorimeter for bio-oil samples, establishes a nuanced understanding crucial for optimizing catalytic performance in sustainable biofuel production.

Dans une bioraffinerie, la biomasse peut être transformée par différents procédés (thermiques, chimiques et biochimiques) en carburants et en produits chimiques à haute valeur ajoutée. Plus spécifiquement, le procédé catalytique d'hydrodésoxygénation (HDO) devrait permettre de valoriser à la fois les bio-huiles obtenues par pyrolyse en biocarburants, ainsi que les composés aromatiques oxygénés issus de la dépolymérisation de la lignine en aromatiques simples.Afin de modéliser la désoxygénation de ces fractions, les isomères du crésol (ortho-, méta- et para-crésol) ont été choisis comme molécules oxygénés modèles. Les réactions ont été effectuées sous haute pression (2-4 MPa) et à des températures comprises entre 250 et 340° C. Plusieurs phases actives à base de molybdène (sulfures et oxyde) et de nickel (métallique et phosphure) ont été étudiées. L'influence du support des phases oxydes de molybdène (SiO2, SBA-15, Al2O3) et des phases à base de nickel (SiO2 et ZrO2) a également été examinée.Dans ces conditions expérimentales, les composés phénoliques sont désoxygénés selon deux voies de transformations parallèles. La voie de désoxygénation directe (DDO) conduit uniquement au toluène par hydrogénolyse de la liaison C-O. La voie hydrogénante (HYD), quant à elle, conduit à un mélange de produits obtenus après hydrogénation du cycle aromatique, impliquant des réactions d'hydrogénolyse, d'hydrogénation, de déshydratation et d'isomérisation. L'activité des catalyseurs ainsi que la contribution de chaque voie de désoxygénation sont dépendantes de la phase active étudiée, du support choisi ainsi que des conditions opératoires utilisées. / In a biorefinery, biomass can be converted by different process (thermal, chemical and biochemical) into fuels and valued-added chemicals. More specifically, the catalytic hydrodeoxygenation (HDO) process could upgrade both bio-oils obtained from pyrolysis into biofuels and oxygenated aromatic compounds from the depolymerization of lignin into aromatics.In order to model the deoxygenation of these fractions, the cresol isomers (ortho, meta and para-cresol) were chosen as model oxygenated molecules. The reactions were carried out under high pressure (2-4 MPa) and temperatures between 250 and 340° C. Several active phases based on molybdenum (sulphides and oxide) and nickel (metal and phosphide) have been studied. The influence of the support of the molybdenum oxide phases (SiO2, SBA-15, Al2O3) and of the nickel-based phases (SiO2 and ZrO2) was also examined.Under these experimental conditions, phenolic compounds are deoxygenated by two parallel pathways. The direct deoxygenation (DDO) route only leads to toluene by hydrogenolysis of the C-O bond. The hydrogenating route (HYD), on the other hand, leads to a mixture of products obtained through the hydrogenation of cresol aromatic ring, involving hydrogenolysis, hydrogenation, dehydration and isomerization reactions. The activity of the catalysts as well as the contribution of each deoxygenation pathway are dependent on the active phase studied, on the support chosen as well as on the operating conditions used.