Robust metal foam-supported LaCeOx catalysts for continuous aldol condensation of biogenic carbonyls toward furanic jet fuel production

Abstract

The aldol condensation of low-molecular-weight biogenic carbonyl compounds plays a pivotal role in constructing longer-chain intermediates for the production of furanic jet fuels. Among these, coupling furfural with ketones has emerged as a promising route due to the high energy density and favorable low-temperature properties of the resulting compounds. In this study, we developed shaped LaCeO_x catalysts to enable an efficient continuous aldol condensation process of furfural and acetone, a key step in the synthesis of furanic jet fuel precursors. Three structured catalyst configurations were evaluated: (i) compressed LaCeO_x powder formed into disk granules, (ii) pelletized LaCeO_x with a bentonite binder, and (iii) a LaCeO_x-coated metal foam monolith. While the disk and pellet catalysts suffered from mechanical degradation and pore blockage due to polymeric byproducts, the metal foam catalyst maintained its structural integrity and exhibited superior productivity. This enhanced performance is attributed to the open-cell structure of the metal foam, which facilitates effective mass transport and suppresses undesired side reactions such as oligomerization. Moreover, the metal foam catalyst demonstrated excellent regenerability via air calcination at 673 K, underscoring its potential for long-term operation. Integration of the optimized aldol condensation with a downstream hydrogenation/hydro-deoxygenation step yielded a furanic jet fuel precursor with an overall carbon yield of approximately 39%, highlighting the feasibility and scalability of this process for renewable aviation fuel applications.