Cascade engineered synthesis of ethyl benzyl acetoacetate and methyl isobutyl ketone (MIBK) on novel multifunctional catalyst

Abstract

A novel trifunctional catalyst with basic, acidic and metal sites was synthesized by nanocolloidal method and used in industrially important reactions. in the laboratory. The synthesized catalyst consisted of palladium and hydrotalcite supported on transition metal modified hexagonal mesoporous silica (HMS) and was characterized in virgin and reused states using a number of techniques such as elemental analysis, FTIR, NH₃− TPD, CO₂− TPD, H₂− TPR, XRD and BET surface area. The activity of particular catalytic site was engineered so that a desired reaction pathway was followed in spite of possibility of multiple series and parallel or complex reactions. One pot cascade engineered synthesis of ethyl benzyl acetoacetate from benzaldehyde and ethyl acetoacetate was studied in solvent free condition in a batch reactor. The effects of various parameters on the rates of reaction were analysed to establish instantaneous selectivity. Reaction mechanism and kinetic modelling was studied to validate the experimental results. The reaction follows Langmuir-Hinshelwood-Hougen-Watson mechanism involving weak adsorption of reactants and products. The apparent activation energy was found to be 13 kcal/mol and intrinsic kinetic constant 33 cm⁶ mol⁻¹ gcat⁻¹ s⁻¹. This study was further extended to synthesis of methyl isobutyl ketone (MIBK) from acetone in solvent free condition. Similar experimental and theoretical analysis was done for MIBK synthesis for which the activation energy and intrinsic kinetic constant were found to be 12 kcal/mol and 4 cm⁶ mol⁻¹ gcat⁻¹ s⁻¹, respectively.