Conventional oxo process

As expected from Table 5.7, this environmental quotient for conventional oxo processes (basis Co catalysts) and for the manufacture of the bulk chemical -butanal is actually about 0.6-0.9, depending on the definition of the term "target" product. The range 0.6-0.9... 

Whereas this important quotient is calculated solely from the product spectrum, process simplifications are a consequence of combining the rhodium catalyst with the special two-phase process. Compared with the conventional oxo process and with other variants (which, for example, include disadvantegeously thermal separation of the oxo reaction products from the catalyst) the procedure is considerably simplified (as shown in several papers, e.g., [2,12]). 

Oxonatlon of llnoar alpha oloflnt glvot primary alcohols of a high dogroo of llnoarlty. From this procoss it is possible to obtain odd-numbered, as well as even-numbered, carbon atom alcohols. These represent a new type of plasticizer raw material in the United States since such alcohols are not commercially available from natural sources, the conventional oxo process, or the ethylene growth process. Phthalate esters of these alcohols exhibit the improved performance In PVC compounds expected of linear alcohols. 

Figure 1 demonstrates impressively that in the RCFI/RP process most of the equipment commonly used for conventional oxo processes is not required. Items 10-15 in particular are superfluous because of the higher selectivity of conversion with Rh catalysts (also expressed in the E factor), whereas the efficient catalyst feed with the two-phase procedure obviates the need for items 3-8. It is therefore... 

Propane, 1-propanol, and heavy ends (the last are made by aldol condensation) are minor by-products of the hydroformylation step. A number of transition-metal carbonyls (qv), eg, Co, Fe, Ni, Rh, and Ir, have been used to cataly2e the oxo reaction, but cobalt and rhodium are the only economically practical choices. In the United States, Texas Eastman, Union Carbide, and Hoechst Celanese make 1-propanol by oxo technology (11). Texas Eastman, which had used conventional cobalt oxo technology with an HCo(CO)4 catalyst, switched to a phosphine-modified Rh catalyst ia 1989 (11) (see Oxo process). In Europe, 1-propanol is made by Hoechst AG and BASE AG (12). 

The switch from the conventional cobalt complex catalyst to a new rhodium-based catalyst represents a technical advance for producing aldehydes by olefin hydroformylation with CO, ie, by the oxo process (qv) (82). A 200 t/yr CSTR pilot plant provided scale-up data for the first industrial,... 

A specific synthesis of 1,3-dioxohexahydroisoquinoline employing a conventional oxo hydrocarboxylation process is outlined in Scheme 149.224... 

Considerable effort over the years has been devoted to a search for new oxo catalysts. This has been motivated by a desire to minimize the less valuable isobutyraldehyde/alcohol and also to lower oxo reaction temperatures and the high pressures (3-4000 psi) associated with the conventional cobalt process for reduced capital investment and increased energy savings. 

The next breakthrough of importance for future 2-ethylhexa-nol plants occurred in the mid seventies. This was the development of the rhodium-catalyzed oxo process by Union Carbide, Davy Powergas and Johnson-Matthey (See Chapter 6). This process not only operates at lower temperatures and pressures than the conventional cobalt-catalyzed process but also gives a far lower yield of the less valuable isobutyraldehyde by-product. The net result is improved economics vs. the cobalt process for n-butyr-aldehyde - the intermediate for 2-ethylhexanol. Although outside the U.S. this new technology has already been licensed and plants are now operating(16), no new plants were constructed in the U.S. specifically for 2EH manufacture in the seventies. However,... 

Hydroformylation of linear olefins in a conventional cobalt oxo process (see Section 5.3) produces increasing linear-to-branched aldehyde ratios as the carbon monoxide ratio in the gas stream is increased up to 5 MPa (50 atm), but there is little further effect if the reaction mixture is saturated with carbon monoxide. An increasing partial pressure of hydrogen also increases this ratio up to a hydrogen pressure of 10 MPa. As the reaction temperature is increased, the linear-to-branched aldehyde ratios decreases. Solvents in conventional cobalt-catalyzed hydroformylation affect the isomer distribution. In propylene... 

The crude aldehyde is fractionally distilled into n- and isobutanal in a conventional aldehyde distillation unit. The reboiler of this n/iso column is designed as a heatabsorbing falling film evaporator incorporated in the oxo reactor, thus providing a neat, efficient method of recovering heat by transferring the heat of reaction in the reactor to cold n-butanal, which subsequently heats the n/iso column. The preferred hydroformylation temperature is 110-130 °C and is therefore used for the production of process steam. Whereas other oxo processes are steam importers, the RCH/RP process including the distillation of n-/isobutanol exports steam. No special pretreatment or even purification steps are necessary for the catalyst. This reduces the environmental burden still further. 

Backgroxmd. Otto Roelen of Ruhrchemie, Germany, was chiefly responsible for development of the Oxo process. Some early work by Smith and his coworkers at the U.S. Bureau of Mines in 1930 had indicated that an increased yield of oxygenated compounds, as compared with conventional fischer-Tropsch practice, was obtmned when ethylene was added to water gas in the presence of cobalt catalyst at 200-225 C and atmospheric pressure. Roelen modified the operating conditions significantly and found that, at temperatures below 200°C "and pressures of 100-200 atm, all liquid products from the reaction of ethylene and water gas were oxygenated. He showed that the reaction could be applied generally to the formation of aldehydes from olefins and filed patents on the process as early as 1938. ... 

Membrane separation processes are always considered in comparison with some other more conventional separation processes, when their economic feasibility is examined. Often, membrane separation alone is not necessarily economically advantageous, but a synergetic effect can be expected when membrane separation is combined with another separation process, in a hybrid system. One such system was proposed by UOP Engineering Products to be incorporated into the oxo-alcohol synthesis process [331]. The oxo-alcohol plant has the following three main operations ... 

Addition reactions of vinyl sulphones (Diels-Alder addition, [2 -i- 2]-photocycloaddition, and conventional functionalization processes, e.g. IN 3 2-azido-l-iodoalkyl sulphones °°) and substitution reactions of / -halogeno-vinyl sulphones have been reported. A point of interest in the cycloaddition study is the effect of ( )-(Z) equilibration in hindering the participation of simple vinyl sulphones in photocycloaddition reactions. Elimination of SO2 has been observed in the photolysis of 3-oxo-alk-l-enyl sulphones in benzene, giving radicals which attack the solvent. ... 

The hydroformylation of olefins is a type of CO insertion reaction that is one of the most important industrial applications of homogeneous catalysis with transition metal complexes (208,209). Conventional industrial processes (e.g., the Oxo process) typically use either cobalt- or rhodium-based catalysts and conduct the reaction in two-phase gas-liquid reactors. Efficient transfer of the reactants from the gas phase into the liquid phase is of primary importance to minimize inherent mass transfer limitations (208). Reactor design thus focuses on optimizing this mass transfer rate by maximizing the interfacial area between phases. An SCE process eliminates this transport restriction since the hydrogen... 

With the RCH/RP process, it is possible to hydroformylate propene up to pentenes with satisfying space time yields. On the other hand, heavier aldehydes such as Cio (iso-decanal) or higher from the hydroformylation of nonene(s), decenes, etc. can not be separated from the oxo catalysts by conventional means such as distillation due to thermal instability at the required temperatures and thus especially needs the careful aqueous-biphasic separation technique. There are numerous attempts to overcome the problem of low reactivity of higher alkenes which is due to low miscibility of the alkenes in water [26,27b, 50a,58d]. These proposals can briefly be summarized as ... 

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