Kinetic Characterization of Multimetallic Catalysts Using An α-β Unsaturated Aldehyde Probe Reaction

The selective hydrogenation of α,β-unsaturated aldehydes is an important reaction for the pharmaceutical industry. Multimetallic catalysts have been widely used to selectively hydrogenate citral, an α,β-unsaturated alcohol, to the desired α,β-unsaturated alcohol. Three types of experiments were conducted. The purpose of the first two sets was to verify that internal and external mass transfer limitations, MTL, and the ?background activity? of the support were not affecting the observed hydrogenation reaction kinetics. The purpose of the third set was to determine the role played by the catalyst precursor on reaction rate. These experiments were performed at 460psig and 70°C for 5 hours in a stirred autoclave reactor. For the MTL experiments, the calculated rate constants were all within a standard deviation of each other, showing that there are no internal or external MTL in the system. For the support ?background activity? experiments, the rate constants for these reactions were all < 5*10^-4 (1/(min)), verifying that the support has negligible affect on reaction rate. Finally, multimetallic samples were prepared from two different precursors. The rate constant of the Pt-Ru-Sn/MgO catalyst was found to be significantly higher than its monometallic and bimetallic counterparts.