Kinetics of One-Stage Wacker-Type Oxidation of C2–C4 Olefins Catalysed by an Aqueous PdCl2–Heteropoly-Anion System

The steady-state kinetics of the one-stage Wacker oxidation of gaseous olefins such as ethene, propene, and 1-butene by oxygen (1:2 stoichiometric mixture of O2 and olefin) to form acetaldehyde, acetone, and methyl ethyl ketone, respectively, was studied in a semicontinuous reactor. The catalytic system involves an aqueous solution of Pd(II) chloride (0.05–2 mM Pd(II), [Pd(II)]/[Cl−]=1:50) and Keggin-type heteropoly anions [PMo9V3O40]6− (50 mM), at 20–50°C. Under these conditions in a steady state, the reactivity of olefins increases in the order ethene ≤1-butene < propene, but the total range is only a factor of 3. The oxidation of 1-butene is accompanied by the double-bond migration to form 2-butene.