(483a) Liquid Phase Aldol Condensation with Shape Selective Amine-Substitued Zeolites

The aldol condensation reactions of furfural and hydroxymethylfurfural (HMF) condensed with acetone and propanal were studied over solid base catalysts MgO-ZrO₂, NaY and amine-substituted NaY (Nit-NaY). The reactions were conducted at 120 °C and 750 psig in batch reactors. Nit-NaY exhibited catalytic activity comparable to MgO?ZrO₂, much higher than that of NaY, with up to 80% conversion of furfural (or HMF) with acetone/propanal, indicating a strong solid base catalyst. MgO-ZrO₂ shows no preference between monomer and dimer products, while Nit-NaY is highly selective to monomer product due to the cage size in the FAU structure. Water content and feed concentration play significant roles on both catalysts. Increasing water concentration in the feed solution or increasing the feed concentration leads to increased catalytic activity and dimer selectivity. The Nit-NaY was not stable and lost in catalytic activity when recycled due to leaching of the nitrogen. Different characterization techniques, including XRD, basic sites titration, CO₂ TPD-MS, TGA and ²⁹Si SP MAS NMR, were used here to characterize the fresh and spent catalysts. The active sites on MgO-ZrO₂ are Mg²⁺-O^2- pairs and surface hydroxyl groups, and the active sites on Nit?NaY are the amines sites associated with sodium cations.