Hydroformylation technology

The need for higher product specificity and milder reaction conditions (see also Section IX) has led to extensive research in hydroformylation technology. This research, as reported in technical journals, patent literature, and commercial practice has been primarily concerned with catalysis by rhodium, in addition to the traditional cobalt, and with catalyst modification by trialkyl or triaryl phosphines. These catalyst systems form the basis for the major portion of the discussion in this chapter some other catalyst systems are discussed in Section VIII. 

An excess of ligand, including CO, will often inhibit isomerisation. HCo(CO)4, an unstable hydrido-carbonyl complex, belongs to the examples of catalysts also active in an atmosphere of CO. This is the only homogeneous catalyst being commercially applied, albeit primarily for its hydroformylation activity. Higher alkenes are available as their terminal isomers or as mixtures of internal isomers and the latter, the cheaper product, is mainly converted to aldehydes/alcohols by hydroformylation technology. Later we will see that the isomerisation reaction also plays a pivotal role in this system. Since 1990 several catalysts based on rhodium, platinum and palladium have been discovered that will also hydroformylate internal products to terminal aldehydes. 

In 2001 Sasol announced the commercialisation of a Rh-catalysed hydroformylation technology, licensed from Kvaemer (Davy McKee), for conversion of Sasol s Fischer-Tropsch 1-alkenes to detergent alcohols, on 120 kt/a scale [55] that is probably using this technology. 

An important development in the past 15 years in hydroformylation technology was the introduction of biphasic homogeneous catalysis. Kuntz (62) expressed the basic idea of a new generation of water-soluble oxo catalysts with triphenylphosphane trisulfonate (tppts as the sodium salt) as a ligand for a rhodium-complex-catalyzed hydroformylation process. Ruhrchemie AG adapted the idea on the basis of research done at Rhone-Poulenc and developed it into an industrially viable process, which was... 

Despite a considerable number of publications and patent applications dealing with hydroformylation technology, comparatively few processes have been commercialized successfully besides those which have already been mentioned in preceding sections. Two processes have gained commercial importance. 

R. Kummer, H. J. Nienburg, H. Hohenschutz, M. Strohmeyer, New Hydroformylation Technology with Cobalt Carbonyls, Paper presented at the Symposium on Homogeneous Catalysis, Chicago, August 1973. 

FIGURE 1.10 Davy Process Technology low-pressure hydroformylation technology was developed in collaboration with The Dow Chemical Company. The LP Oxo process has been applied commercially to produce detergent-grade alcohols from higher olefin cnts from FT synthesis. (From Renaud, R, CESIO 6th World Surfactants Congress, Berlin, June 20-23, 2004. With permission.)... 

The production of alcohols from olefins using hydroformylation technology is now an established procedure. Several strategies have been developed, ranging from separate hydroformylation and hydrogenation steps using different catalysts and reaction vessels to hydroformylation tandem reactions, which proceed in a... 

Over the last 40 years the economic importance of industrial aldehyde production has led chemists and engineers to propose new and alternative ways to further optimize hydroformylation technologies. Particular attention in these attempts was always given to new concepts by which to combine the molecular defined, homogeneous nature of hydroformylation catalysis with cleverer ways to separate products and catalyst after reaction. Many of the reported strategies have focused on the... 

Given the fact that IL research in general - and catalysis in ILs in particular - is a very young research field it is too early to conclude from the Ust in Table 6.14.4 whether IL based, liquid-liquid biphasic hydroformylation technologies will make their way into industrial practice. However, every new development that helps to overcome one of the weak points will help to make industrial success more likely. 

Recovery and recycle of homogeneous catalysis are said to be the focal point of any new generation of, for example, hydroformylation technologies. Additionally, the costs of the new process are determined by the losses - an argument which is specially tabled at the occasion of discussions about the use of high-price rare metal catalysts such as rhodium or palladium. Obviously this is true because a new mode of recycling characterizes a new process. But on the other hand, metal losses (and supplementary ligand costs) are only a (minor) part of the overall cost as will be demonstrated in Section 12.4. 

A new inverted biphasic catalysis system using supercritical CO2 as the stationary catalyst phase and water as the continuous phase was described for rhodiumotalyzed hydroformylation of polar substrates. Product separation and catalyst recycling was possible without depressurizing the autoclave. Turnover numbers of up to 3560 were obtained in three consecutive runs and rhodium leaching into the aqueous phase was below 0.3 ppm [125]. Hydroformylation of propene was carried out in supercritical carbon dioxide + water and in supercritical propene + water mixtures using Rh(acac) (CO)2 and P(m-C6H4S03Na)3 as catalysts. Compared to traditional hydroformylation technology, the supercritical reactions showed better activity and selectivity [126]. 

---