Current Hydroformylation Catalyst and Process Technologies

Catalyst development in hydroformylation started with the discovery of the reaction in 1938 and has led to several major new developments during intensive industrial appUcation of the reaction. Thereby, irmovations in catalyst and process technologies went hand-in-hand. The introduction of Rh-based hydroformylation required, for example, much stricter requirements with regard to catalyst separation, recovery, and recycle compared to Co-based technologies due to the much higher price of the catalytic metal (by about a factor of 1000). 

Very efficient and sophisticated catalyst recovery technologies paved not only the way for the application of the more expensive metal rhodium but also allowed the use of more sophisticated and expensive ligand systems that have to be recycled in the same way. 

In the following, the most important catalyst and process technologies for industrial olefin hydroformylation are presented and their specific advantages and disadvantages are discussed. Table 6.14.1 gives an overview of the different processes described in more detail throughout this subchapter. 

Typical feed Internal C4-C17 Internal C4-C17 Propylene Propylene 

From 1974 onwards, Rh-based hydroformylation became industrial. The use of a catalyst metal that is about 1000-times more expensive than cobalt was driven by several reasons. First, Rh-hydroformylation is more active and thus requires much lower process pressures (lower energy consumption in compression units) and smaller reactors. Second, Rh-hydroformylation shows a very high selectivity to the aldehyde product with only minimal hydrogenation activity being observed. This is of particular importance for propylene hydroformylation where butyl alcohol is not the principle market use. In contrast, for the desired end-use of w-butyraldehyde in the form of its aldol condensation product 2-ethylhexanol a pure aldehyde feed is required as hemiacetals (formed by reaction of aldehyde and alcohol) complicate product purification and add to operating costs. 

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