Wacker process

The Wacker process (also Wacker- Hoechst process called ) is a large-scale process in the chemical industry, in which a catalytic oxidation of alkenes occurs by molecular oxygen.

The Wacker Chemie AG ( Germany ) in the early 1960s by Walter Hafner, Jürgen Smidt and other developed method was among the first that were suitable to refer to the future importance of alkenes. Enormous amounts of aldehydes are produced annually by this method. It was the general opinion that "the invention of the Wacker Process a triumph of common sense " is. This method can be obtained, for example, ethene ( C2H4) acetaldehyde ( CH3CHO ). Acetaldehyde can in turn be oxidized to acetic acid ( CH3COOH ).

Method

The Wacker process or the Wacker process leads as well as the also large industrial hydroformylation carried out to aldehydes, with the difference that in the hydroformylation takes place a chain extension and this is catalyzed by other transition metals.

The running cycle can be summarized in the following equations:

There are the one-step and two-step process. The one-step method, the oxidation of ethene, and the regeneration of the catalyst is carried out in a reactor. The regeneration must be done with pure oxygen, also the ethene used must be very pure. In order to stay below the explosion limit, working with an excess of ethene, thus the yield drops to about 35%. Unreacted ethylene may, however, be performed again in the reactor.

The two-stage process, the oxidation of ethene, and the regeneration of the catalyst are spatially separated. It can be regenerated with atmospheric oxygen. The purity of ethene is less than one-stage procedure. However, the investment costs in the plants and the energy consumption during the two-stage method are significantly higher, which is why, when the power supply is ensured with pure oxygen, the one-step method prefers.

The yield for the two processes process at about 95 %.

The Wacker- Hoechst process becomes less important, as not the aldehydes, but their secondary products industry play a crucial role and this (eg acetic acid or acetic anhydride) are increasingly made ​​on the use of synthesis gas.