α-Akylation of aliphatic ketones with alcohols: base type as an influential descriptor

Current global challenges associated with energy security and climate emergency, caused by the combustion of fossil fuels (e.g., jet fuel and diesel), necessitate the accelerated development and deployment of sustainable fuels derived from renewable biomass-based chemical feedstocks. This study focuses on the production of long-chain (straight and branched) ketones by direct α-alkylation of short chain ketones using both homogenous and solid base catalysts in water. Thus, produced long-chain ketones are fuel precursors and can subsequently be hydrogenated to long-chain alkanes suitable for blending in aviation and liquid transportation fuels. Herein, we report a thorough investigation of the catalytic activity of Pd in combination with, (i) homogenous and solid base additives; (ii) screening of different supports using NaOH as a base additive, and (iii) a comparative study of the Ni and Pd metals supported on layered double oxides (LDOs) in α-alkylation of 2-butanone with 1-propanol as an exemplar process. Among these systems, 5%Pd/BaSO4 with NaOH as a base showed the best results, giving 94% 2-butanone conversion and 84% selectivity to alkylated ketones. These results demonstrated that both metal and base sites are necessary for the selective conversion of 2-butanone to alkylated ketones. Additionally, amongst the solid base additives, Pd/C with 5% Ba/hydrotalcite showed the best result with 51% 2-butanone conversion and 36% selectivity to the alkylated ketones. Further, the screening of heterogenous acid-base catalysts 2.5%Ni/Ba1.2Mg3Al1 exhibited an adequate catalytic activity (21%) and ketone selectivity (47%).