Pd/C-CaO-catalyzed Α-alkylation and hydrodeoxygenation of an acetone-butanol-ethanol mixture for biogasoline synthesis

A solvent-free α-alkylation of acetone with butanol and ethanol was conducted using a mixture of Pd/C and CaO as heterogeneous catalysts. After reaction at 180 °C for 20 h, alkylated products, including C₅-C₁₁ketones and alcohols, were obtained with a total yield of 78.1%. After this α-alkylation, consecutive hydrodeoxygenation at 270 °C for 20 h under H₂at 500 psig yielded 74.7% C₅–C₁₁alkanes based on the amount of acetone. The product could be used as a bio-gasoline. After alkylation, the catalyst was isolated and characterized using XRD, TGA, XPS, and TEM to elucidate the deactivation of the catalyst. The main reason was found to be decreased basicity of Ca species by conversion of CaO to CaCO₃during the reaction. The Pd/C particles were slightly agglomerated after alkylation, but still retained their catalytic activity during successive reuses for the alkylation reaction. In subsequent runs, the activity of the used catalyst could be recovered by adding a sufficient amount of CaO, or by decarboxylation of CaCO₃to CaO at 500 °C, under H₂.