THE LIQUID-PHASE HYDROGENATION OF METHYLACETOACETATE USING NICKEL-EXCHANGED Y-ZEOLITE CATALYSTS .1. STRUCTURE SENSITIVITY

The liquid-phase hydrogenation of methylacetoacetate (MAA) over NiNaY and NiKY zeolites to a racemic methyl 3-hydroxybutyrate (MHB) product has been studied in a stirred reactor under a constant hydrogen purge. The variation of MHB formation with time was monitored and reaction rates accurate to +/-2% are reported. The effects of variations in the supported nickel metal particle sizes (in the range 16-75 nm) on the hydrogenation activity were examined by altering either the degree of nickel exchange or the temperature of reduction. It is shown that the hydrogenation of MAA at 343 K is structure-sensitive and a correlation between reaction sensitivity and particle size is presented. Data on the reaction over Ni/SiO2 catalysts are also provided for comparison purposes. Both the zeolite and silica-based catalysts were reusable and could be stored in the reaction solvent for extended periods of time without an appreciable loss of activity.