Ruhrchemie process operation

Eventually, the spent catalyst solution has to leave the oxo loop for work-up. The Ruhrchemie works of Celanese AG in Oberhausen (Germany) operate several rhodium-based oxo processes besides the well-known Ruhrchemie/Rhone-Poulenc process (RCF1/RP, the described low pressure oxo process with TPPTS-modified Rh catalyst), there are the Ruhrchemie process with an unmodified Rh catalyst at high pressure (comparable to the late ICI process [76] this variant is for the benefit of a high iso/n ratio... 

Since in some of the preliminary experiments no rhodium losses could be detected, it is assumed that in an optimised continuous process the metal leaching will be in the range of the biphasic Ruhrchemie/Rhone-Poulenc process operating around 1 ppb. This would result in a loss of rhodium of 0.1 kg per year which is approximately 0.7 % in the case of the biphasic ionic liquid process and 0.2 % in the case of the SILP process. The inventory of the ionic liquid is slightly lower in the case of the liquid-liquid... 

A breakthrough in the hydroformylation of propene was achieved following the synthesis of the water soluble ligand tppts for the preparation of the RhH(CO)(tppts)3 catalyst345 which formed the basis for the development of the Ruhrchemie/Rhone-Poulenc two phase process. This process operates under mild reaction conditions giving excellent n/i ratios and easy separation of products from the catalyst by decantation with virtually no catalyst leaching. 

With optimized process operation the reaction is strongly regioselective. The process is commercialized by Rhone-Poulenc using Ruhrchemie s TPPTS and yields precursors for vitamin E cf. Section 3.1.1.1.3 [163, 164] Sc or Y triflates catalyze aqueous biphasic reactions which are alternatives to base-catalyzed processes such as aldol or Michael-type conversions [257]. 

The aldolic condensation of butyraldehyde occurs in the presence of caustic soda, which acts as a catalyst (Ruhrchemie process). The system operates in this case between 80 and 130 C and between 03 and 1.106 Pa absolute. The continuous removal of one molecule of water yields 2-ethylhexenal, which is hydrogenated in the presence of a nickel catalyst between 100 and 15IPC and between 5 and 10.10 Pa absolute. 

Despite the fact that the Shell process operates at lower pressure and higher temperatures than the conventional processes, still higher n/iso ratios of the products formed are observed. Thus, in the hydroformylation of propylene an 88/12 ratio of n- over iso-product is obtained, whereas for comparison the distribution in the Ruhrchemie process is 80/20. This type of modified catalyst is not only a hydroformylation but also a hydrogenation catalyst. Thus, in the SheU process about 10-15 % of the olefin fed is lost through hydrogenation to the paraffin whereas the figures for the conventional 0X0 processes are only about 2-3 %. 

In recent years, the name has also come to include the production of downstream products (e.g., alcohols and acids) from the aldehydes. Invented by O. Roelen in 1938 at the Chemische Verwertungsgesellschaft Oberhausen. Further developed by Ruhrchemie and IG Farbenindustrie in Germany during World War II, the process was first commercialized in 1948. Originally, the process operated at high pressure, and dicobalt octacarbonyl, Co2(CO)g, was used as a homogeneous catalyst. The present process, known... 

The economic and environmental benefits of the Ruhrchemie-Rhone-Poulenc process have been closely scrutinized since the plant has been in operation. 

The third generation process concerns the Ruhrchemie/Rhone-Poulenc process utilizing a two-phase system containing water-soluble rhodium-tppts in one phase and the product butanal in the organic phase. The process has been in operation since 1984 by Ruhrchemie (or Celanese, nowadays). The system will be discussed in section 8.2.5. Since 1995 this process is also used for the hydroformylation of 1-butene. 

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... 

In 1975 Kuntz has described that the complexes formed from various rhodium-containing precursors and the sulfonated phosphines, TPPDS (2) or TPPTS (3) were active catalysts of hydroformylafion of propene and 1-hexene [15,33] in aqueous/organic biphasic systems with virtually complete retention of rhodium in the aqueous phase. The development of this fundamental discovery into a large scale industrial operation, known these days as the Ruhrchemie-Rhone Poulenc (RCH-RP) process for hydroformylation of propene, demanded intensive research efforts [21,28]. Tire final result of these is characterized by the data in Table 4.2 in comparison with cobalt- or rhodium-catalyzed processes taking place in homogeneous organic phases. 

There are many important points and lessons to be learned from the development and operation of the Ruhrchemie-Rhone Poulenc process and we shall now have a look at the most important ones. 

Prewar Development of Synthesis Operation in Germany. The production of significant quantities of liquid hydrocarbons from synthesis gas over a cobalt catalyst was first reported by Fischer and Tropsch (6) in 1926. In 1932 a catalyst, useful for commercial operations, was described by Fischer and Koch (4), and in 1935 Ruhrchemie built the first full scale synthesis plant, which operated, at atmospheric pressure. In 1936, the process was modified by the work of Fischer and Pichler (5) to operate at. 5 to 15... 

Table V shows the salient features of several Fischer-Tropsch processes. Two of these—the powdered catalyst-oil slurry and the granular catalyst-hot gas recycle—have not been developed to a satisfactory level of operability. They are included to indicate the progress that has been made in process development. Such progress has been quite marked in increase of space-time yield (kilograms of C3+ per cubic meter of reaction space per hour) and concomitant simplification of reactor design. The increase in specific yield (grams of C3+ per cubic meter of inert-free synthesis gas) has been less striking, as only one operable process—the granular catalyst-internally cooled (by oil circulation) process—has exceeded the best specific yield of the Ruhrchemie cobalt catalyst, end-gas recycle process. The importance of a high specific yield when coal is used as raw material for synthesis-gas production is shown by the estimate that 60 to 70% of the total cost of the product is the cost of purified synthesis gas.

The prototype industrial process based on this concept is the Ruhrchemie-Rhone Poulenc process for the hydroformylation of propylene to butanal94,219,220 (see Section 7.3.1). Because of the use of appropriately modified water-soluble ligands, the catalyst resides and operates in the aqueous phase. The particular features of this process are the positive energy balance and easy catalyst recovery, namely, the simply circulation of the aqueous catalyst solution. New types of water-soluble Ir and Rh complexes with tris(hydroxymethyl)phosphine222 were described, and the biphasic hydroformylation of 1-hexene was accomplished in ionic liquids.223 A cationic sugar-substituted Rh complex displays high regioselectivity to branched aldehydes.224... 

Ever since the plant went online, a great deal of fundamental research has been conducted, the process has been scaled-up further and new plants have come into operation. The economic and environmental benefits of the Ruhrchemie-Rhone-Poulenc process have been closely scrutinised. Overall the cost of the production is reduced, but it is the benefits to the environment... 

Only limited data are available for the kinetics of oxo synthesis with the water-soluble catalyst HRh(CO)(TPPTS)3. The hydroformylation of 1-octene was studied in a two-phase system in presence of ethanol as a co-solvent to enhance the solubility of the olefin in the aqueous phase [115]. A rate expression was developed which was nearly identical to that of the homogeneous system, the exception being a slight correction for low hydrogen partial pressures. The lack of data is obvious and surprising at this time, when the Ruhrchemie/ Rhone-Pou-lenc process has been in operation for more than ten years [116]. Other kinetic studies on rhodium-catalyzed hydroformylation have been published, too. They involve rhodium catalysts such as [Rh(nbd)Cl]2 (nbd = norbomadiene) [117] or [Rh(SBu )(CO)P(OMe)3]2 [118], or phosphites as ligands [119, 120]. 

A far more elegant solution was the one offered by the Ruhrchemie/Rhone-Poulenc (RCH/RP) process, which was established in 1984 on an industrial scale threefold in mem-sulfonated triphenylphosphine (TPPTS, as sodium salt) as the ligand yields the water-soluble catalyst HRh(CO)(TPPTS)3. Because of the mutual insolubility, the separation of the aqueous catalyst phase and the butanals was extremely simplified, circumventing all the common difficulties and leading to very efficient operation. 

There are recent literature reports according to which alcohols and aldehydes dehydrogenate in the presence of ammonia to form nitriles. Process are operated by Rohm Haas, Ruhrchemie, and Bayer [21-23]. Molybdenum nitrides were found most efficient as heterogeneous catalysts [15] cf. eqs. (8) and (9) (R = n-CsHv). They also effect dehydrogenation of amines, as demonstrated for -butylamine in eq. (10). 

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 hydroformylation of propene to form butyralde-hyde invariably produces some isobutyraldehyde at the same time (reaction 1.21).216 One of the best processes uses a water-soluble rhodium phosphine complex to produce 94.5% of the former and 4.5% of the latter.217 The products form a separate layer that is separated from the water. Rhodium is expensive so it is important to lose as little as possible. In 10 years of operation by Rhone-Poulenc-Ruhrchemie 2 million metric tons of butyralde-hyde have been made with the loss of only 2 kg of rhodium. The process is 10% cheaper than the usual one. Higher olefins are not soluble enough in water to work well in the process. The process does work for omega-alkenecar-boxylic acids such as 10-undecenoic acid, where a 97 3... 

The Ruhrchemie/Rhone-Poulenc Oxo process (Figure 4.1, Scheme 4.1) was developed for the synthesis of butyraldehyde from propylene and synthesis gas, where the water-soluble tris(m-sulfonated-phenyl)phosphine (TPPTS)-modified rhodium catalyst operates in the aqueous phase [14]. 

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