Biomass-derived Aldol Condensation on Potassium-Exchanged Hierarchical Zeolites for Sustainable Jet Fuel Production

Abstract

Pursuing the sustainable production of fuels and chemicals is needed to help alleviate the environmental stress of emissions from nonrenewable fossil fuel refining. Energy-dense jet fuel precursors and additives can be renewably produced by upgrading biomass-derived oxygenates through a series of reactions. This thesis focuses on one of these potential reactions, the aldol condensation of furfural and acetone, which can be catalyzed by zeolites. However, the widespread application of zeolites is limited due to deactivation by carbonaceous species, especially during the production of higher molecular weight hydrocarbons. Conventional zeolites can be altered to form hierarchical analogs by incorporating mesopores, which has been shown to increase the conversion of bulky molecules and reduce diffusion constraints. Reduced deactivation has also been shown on zeolites that have modified acid-base character, which is done by ion-exchanging a basic metal, such as potassium, into the framework. This thesis aims to investigate the effects of mesopores and potassium ion-exchange on the zeolite BEA during the aldol condensation of furfural and acetone. Synthesis and characterization of hierarchical zeolites containing auxiliary mesopores and potassium-exchanged sites were done to determine if adding these post-synthetic modifications to BEA would increase furfural conversion by reducing diffusion or reaction limitations. This research suggests that the aldol condensation of furfural and acetone should be run in an inert solvent at a 1:1 molar ratio of acetone:furfural to avoid stoichiometric flooding of zeolite pores with acetone. Future research is necessary to understand the reactivity of zeolites during the aldol condensation reaction of furfural and acetone and other reactions in biomass valorization pathways.