Acetaldehyde single-stage process

FIGURE 1 Acetaldehyde manufacture by the single-stage process. 

The liquid-phase oxidation of ethylene to acetaldehyde was pioneered by the Consortium fiir Elektrochemische Industrie G.m.b.H. Industrially, the single-stage process was developed mainly by Farbwerke Hoechst A. G. and the two-stage process by Wacker Chemie G.m.b.H. itself. Both processes are licensed by Aldehyd G.m.b.H., jointly owned by Wacker Chemie G.m.b.H. and Farbwerke Hoechst G.m.b.H. The basic patents of these two companies on the Wacker process are listed in Table IV. In addition to these patents, which have given Wacker Chemie G.m.b.H. and Farbwerke Hoechst a dominant role in this field, other companies hold some patents in this area (Table X). How many of the patents listed in Tables IX and X are commercially important cannot be judged, based on the open literature alone. 

For commercial production of acetaldehyde using a mixture of ethylene and oxygen in a single-stage process, very pure starting materials are necessary as outlined in Section 2.4.1.4. 

Figure 2. Acetaldehyde from ethylene, single-stage process (a) reactor, (b) separating vessel, (c) cooler, (d) scrubber, (e) crude aldehyde tank, (f) light ends distillation,...

In the single-stage process (Figure 2) a mixture of ethylene and oxygen is passed through an aqueous solution of copper chloride and palladium chloride placed in a towerlike reactor (a). Acetaldehyde is formed according to eq. (6). 

A similar single- or two-stage process has been developed for the manufacture of acetone from propene (110-120 °C, 10 atm, PdCl2-CuCl2-HCl catalyst) but on a smaller scale (80 000 t/year) than for acetaldehyde (2 500 000 t/year).405 The yield is ca. 93%. 

Acetic acid is manufactured by three processes acetaldehyde oxidation, //-butane oxidation, and methanol carbonylation.Ethylene is the exclusive organic raw material for making acetaldehyde, 70 percent of which is further oxidized to acetic acid or acetic anhydride. The single-stage (Wacker) process for making acetaldehyde involves cupric chloride and a small amount of palladium chloride in aqueous solution as a catalyst. 

The commercial Wacker process for the manufacture of acetaldehyde operates in a single-stage... 

Single-Stage Acetaldehyde Process from Ethylene... 

Acetaldehyde may be prepared from ethylene via the Wacker process, and then oxidized as above. In more recent times, a cheaper, single-stage conversion of ethylene to acetic acid was commercialized by chemical company Showa Denko, which opened an ethylene oxidation plant in Oita, Japan, in 1997. The process is catalysed by a palladium metal catalyst supported on a heteropoly acid such as tungstosilicic acid. It is thought to be competitive with methanol carbonylation for smaller plants (100-250 kt/a), depending on the local price of ethylene. 

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