Hydroformylation plant

When a catalyst has sufficiently deactivated to justify taking some action is determined by economics. Both Gas and Liquid Recycle hydroformylation plants may be operated to give essentially constant production rates as the catalyst deactivates. Hydroformylation is approximately first order in both rhodium and alkene concentration. As the rhodium catalyst deactivates, the alkene concentration may be allowed to increase to compensate for the declining catalyst activity. Action is taken when the alkene efficiency declines to the point where it approximates or exceeds the cost of catalyst replacement or reactivation. 

Of course, there is still a large amount of research to be done to develop further the very preliminary character of the above described economic evaluation of an ionic liquid hydroformylation process. Only on the basis of more detailed data it will be possible to decide whether we will see an industrial hydroformylation plant using ionic liquids in the future. 

In rhodium hydroformylations, highly efficient separation and recovery of catalyst becomes imperative, because of the very expensive nature of the catalyst. Any loss, by trace contamination of product, leakage, or otherwise, of an amount of rhodium equivalent to 1-2 parts per million (ppm) of aldehyde product, would be economically severe. The criticalness of this feature has contributed to some pessimism regarding the use of rhodium in large hydroformylation plants (63). However, recent successful commercialization of rhodium-catalyzed processes has proved that with relatively simple process schemes losses are not a significant economic factor (103, 104). 

The Development of the First Aqueous-Organic Biphasic Hydroformylation Plant... 

The tppts process has been commercialised by Ruhrchemie (now Celanese), after the initial work conducted by workers at Rhone-Poulenc, for the production of butanal from propene. Since 1995 Hoechst (now Celanese) also operates a hydroformylation plant for 1-butene. The partly isomerised, unconverted butenes are not recycled but sent to a reactor containing a cobalt catalyst. The two-phase process is not suited for higher alkenes because of the... 

The new hydroformylation plants for the production of butylaldehyde from propene are all based on rhodium catalysts. 

Co, Rh, Pt, and Ru belong to the group of six transition metals forming the most active oxo catalysts. Today s hydroformylation plants operate exclusively with catalysts based on rhodium or cobalt, namely HCo(CO)4, HCo(CO)3PBu3 and HRh(CO)(PR3)3 [9] (see Section 2.1.1.4). 

A breakthrough occurred in the mid-seventies when Union Carbide and Celanese introduced Rh/phosphine catalysts in commercial processes. This catalyst is based on the work by Wilkinson s group he received the Nobel prize for his work in 1973. Rhodium-based catalysts are much more active than cobalt catalysts and, imder certain conditions, at least for 1-alkenes, they are also more selective. The processes for the hydroformylation of higher alkenes (detergent alcohols) still rely on cobalt catalysis. A new development is the use of water-soluble complexes obtained through sulphonation of the ligands (Ruhrchemie). The new hydroformylation plants for the production of butyl-aldehyde from propene are all based on rhodium catalysts. 

Starting in 1999, the Ruhrchemie/Rhone-Poulenc process will be operated in plants having a capacity of about 600,000 metric tons per year, which corresponds to over 10% of the aimual world production of C4 products the first licensed plant is operating in Korea (Hanwha Chem. Corp.). On the Ruhrchemie site, a butene hydroformylation plant [to produce n-valeraldehyde (pentanal)j is also operating without problems. 

The exclusively used cobalt catalysts in commercial hydroformylation plants are HCo(CO)4 and HCo(CO)3(PR3) [30-36]. Two factors are responsible for them in... 

View of the Oberhausen propene hydroformylation plants of OXEA the units produce 650 kt of butyraldehydes peryearwith a Rh-catalyst system immobilized in an aqueous reaction phase ( Oxea). 

In a real life hydroformylation plant all the above-mentioned complications have to be mastered to operate the plant at the economically acceptable level of Rh loss. This requires a very robust process technology and experienced and skilled personal operating the respective hydroformylation process. 

The annual industrial production volume of aldehydes and their downstream products (alcohols, carboxylic acids, esters, plasticizers, detergents, surfactants, lubricants, fuel additives, solvents, fine chemical intermediates, etc.) is rather impressive. Between 9 and 10 million tons of aldehydes are produced worldwide. Over 5 million tons just of C oxo products per year come from chemical industry s hydroformylation plants. In the light of today s discussion about sustainability issues of chemical synthesis, the atom economy of the oxo process as a (formally) waste-free intermolecular addition reaction of three molecular components is well worth mentioning. 

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