Catalytic Hydrodeoxygenation of Sugar Acids to Dicarboxylic Acids

University Of Puerto Rico Mayaguez, Mayaguez PR

Investigators

Abstract

Exploratory research will be conducted to assess the feasibility of potentially transformative catalyst technology for manufacturing dicarboxylic acids from renewable sources of carbon such as lignocellulosic biomass. Current industrial processes for these acids - which are used widely in the production of polymers, pharmaceuticals, solvents, textiles, and plastics - rely on petrochemical feedstocks derived from fossil sources, and utilize relatively harsh conditions and energy-intensive separations. Biomass sources potentially offer a more direct synthesis route while contributing to energy sustainability. The study will address challenges associated with specific chemical reactions at oxygen-containing groups in the carbon structure, while also exploring catalyst formulations that decrease the need for expensive precious metal catalyst components. Recently, interest has surged in the production of dicarboxylic acids from renewable sources, mainly via fermentation of glucose or through further processing of waste byproducts from natural bio-processing such as tartaric acid from wine-making. Specifically, the study will target two model tartaric acid reactions: deoxydehydration to maleic acid and hydrodeoxygenation to succinic acid, both carried out in commonly available solvents. The study will address two overarching objectives, 1) the development of a heterogeneous catalyst comprised of rhenium oxide supported on gallium-promoted cerium dioxide, and 2) a study of the catalytic performance of the rhenium oxide catalysts, prepared in various ways, on the deoxydehydration and hydrodeoxygenation of vicinal diols in tartaric acid. A key aspect of the study is the extent to which supporting the rhenium oxide on the gallium-promoted cerium dioxide can enhance the stability of the catalyst while eliminating the need for common precious metal components such as palladium or iridium, thus paving the way for more durable and lower cost catalysts. Successful demonstration of the proposed catalyst formulation depends on the extent to which the gallium-promoted cerium oxide support can both stabilize isolated monomeric rhenium oxide species (of varying oxidation state) and achieve the facile dissociation of hydrogen gas, as required for the sequential hydrogenation reactions and for regeneration of the active rhenium site. Both of those functions are typically achieved through the incorporation of palladium in the catalyst synthesis. Data suggesting the possibility of eliminating the expensive noble metal component, while stabilizing the active rhenium species, would open a path to transformative catalyst technologies for producing dicarboxylic acids from biorenewable carbon feedstocks. The study also includes an education plan aimed at increasing the involvement of undergraduate Hispanic women in research, and enhancing undergraduate curricula at the PI's institution in key areas related to nanotechnology, engineering materials, and renewable energy.