Catalysis of Organic..

Canning, Gamman, Jackson and Urquart 679. Synthesis of Methyl Isobutyl Ketone over aMultifunctional Heterogeneous Catalyst:Effect of Metal and Base Components onSelectivity and ActivityArran S. Canning, Jonathan J. Gamman, S. David Jackson andStrath UrquartWestCHEM, Dept. of Chemistry, The University, Glasgow G12 8QQ, Scotland.Abstractsdj@chem.gla.ac.ukFour catalyst systems, Pd-KOH/silica, Pd-CsOH/silica, Ni-KOH/silica, and Ni-CsOH/silica, have been investigated for the conversion of acetone to MIBK.Nickel catalysts were generally less selective, with MIBK being furtherhydrogenated to MIBC, and isophorone becoming a major product at hightemperatures. KOH-based catalysts were found to be less active than theirCsOH-based counterparts. The activation energy for MIBK productionsuggested that the rate determining step was within the base catalyzed part of thereaction sequence and this was supported by the product distributions.IntroductionCondensation reactions are an important route to the industrial synthesis of awide range of compounds including solvents such as methyl isobutyl ketone(MIBK) and Guerbet alcohols for use as lubricants and surfactants. Thesynthesis of MIBK from acetone proceeds via a base extraction of the α-protoncatalyzed by aqueous NaOH and intermolecular attack of the carbonyl group toproduce diacetone alcohol. Subsequent acid catalyzed dehydration of diacetonealcohol (DAA) to mesityl oxide (MO) by H 2 SO 4 at 373 K is followed byhydrogenation of MO to MIBK using Cu or Ni catalysts at 288 – 473 K and 3-10 bar (1). Recently however new one-step technology has been developed andcommercialized using palladium on acidic ion-exchange resins (2). The changefrom the three-step process to a single-step significantly reduces the amount ofwaste generated at the base catalysis stage and removes the need forconcentrated sulphuric acid and its residues. Research in this area isnevertheless continuing with a view to improving the process further (3, 4).In this study we have investigated utilizing a bi-functional catalyst with asolid base function for the aldol condensation reaction and a metal function forthe hydrogenation. This work is a continuation of the study that examined thesupported base catalyzed aldol condensation of acetone (5, 6). In those studies