Optimization of the Pd-Catalyzed Alkylation of the Fermentation-Derived Oxygenates Acetone and Butanol toward Sustainable Aviation Fuel (SAF) Intermediates

Sustainable aviation fuels (SAFs) can be produced from renewable carbon sources via fermentation to short-chain oxygenates, followed by alkylation and hydrodeoxygenation. In this study, the alkylation of acetone with butanol as representative fermentation-derived compounds was optimized and characterized using a benchmark Pd/C catalyst and K₃PO₄ as a base additive, aiming for an enhanced conversion of acetone and maximized selectivity toward 6-undecanone (C11). Process optimization was performed via a multivariate analysis by modifying the temperature, catalyst loading, and base loading, with optimal conditions found to be 150 degrees C, 0.5 wt % Pd/C, and 15 wt % K₃PO₄, respectively. Notably, the low Pd/C loading provided unprecedentedly high C11 selectivity (70.2%) with high acetone conversion (94.1%), thereby proving satisfactory reaction performance with lower catalyst loadings than previously reported. Furthermore, the optimized two-step alkylation process was modeled, providing rate constants of 0.0715 h^-1 M^-2 and 0.0347 h¹ M¹, respectively, assuming first-order kinetics for the solvent butanol.