Development of Heterogeneous Wacker Oxidation Catalysts: The Role of the Support and the Redox Component

摘要

The Wacker process is a liquid phase catalytic process for the direct oxidation of ethene to acetaldehyde. The homogeneous catalyst consists of an aqueous solution of palladium(II) chloride and copper(II) chloride, with copper(II) chloride acting as a co-catalyst for the in situ reoxidation of palladium. The most important drawbacks are the lower reaction rate of higher alkenes and the increased production of (undesired) chlorinated side products. To overcome these disadvantages several attempts have been made to develop a heterogeneous version of the process in which alkenes are oxidized in the gas phase. One of the objectives of the research described in this thesis was to further investigate and explain the influence of the support and of the redox component activity of the catalyst. The work described in this thesis shows that it is possible to oxidize 1-butene in the gas phase over a heterogeneous catalyst with high selectivity and a good activity. The Heteropolyanion (HPA) and Palladium salts of heteropolyanions (PdHPA) catalysts appear to be the most promising heterogeneous catalysts. Their initial activity is of the same order of magnitude as the activity of the homogeneous Wacker catalyst.