Cobalt modified synthesis catalyst

Support modification has been reported earlier in the open literature [5,6,7,8,9]. Zirconia modification of silica supports was used to prevent the formation of unreducible cobalt-silicates [5]. Zr, Ce, Hf, or U modification of titania supports was reported to prevent the formation of cobalt-titanates during regeneration [6]. To increase the porosity of titania supports, they were modified with small amounts of binders, e.g. silica, alumina or zirconia [7]. Lanthanum oxide promotion of alumina was reported to be beneficial for improved production of products with higher boiling points [8], and zirconia modification of alumina supports was carried out to decrease the interaction of cobalt with alumina [9]. All these modified supports were either used for fixed bed cobalt based Fischer-Tropsch synthesis catalysts or they were used for slurry phase cobalt catalysts, but not tested under realistic Fischer-Tropsch synthesis conditions in large scale slurry bed reactors. 

Table 9.8 gives economic data about Oxo synthesis on propylene for processes using cobalt tetracarbonyl hydride phosphine-modified cobalt and phosphine-modified rhodium catalysts. 

Fischer-Tropsch A process for converting synthesis gas (a mixture of carbon monoxide and hydrogen) to liquid fuels. Modified versions were known as the Synol and Synthol processes. The process is operated under pressure at 200 to 350°C, over a catalyst. Several different catalyst systems have been used at different periods, notably iron-zinc oxide, nickel-thoria on kieselgtihr, cobalt-thoria on kieselgiihr, and cemented iron oxide. The main products are C5-Cn aliphatic hydrocarbons the aromatics content can be varied by varying the process conditions. The basic reaction was discovered in 1923 by F. Fischer and... 

Cobalt was the first catalyst used in commercial applications of the oxo-synthesis. In order to stabilize the HCo(CO)4 catalyst, high pressures are necessary with a maximum n/i ratio of 80/20. In the Shell process,324,325,393 cobalt catalysts modified with alkylphosphines e.g. ( )3 ( 4 9) are more selective towards linear products but exhibit high hydrogenation activity and are therefore mainly used for the direct synthesis of long chain alcohols. 

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... 

As mentioned above, most published papers and patent applications deal with ligands and their influence on activity and selectivity in the oxo synthesis. When alkylphosphine-modified cobalt catalysts were introduced by Shell [135], high n/i selectivities were reported. However, coordination of phosphine ligands makes the metal-hydrogen bond more hydridic, therefore leading to substantial formation of hydrogenation products. Hydroformylation of 1-pentene yielded hex-anol with 91 % linearity. 

This method is efficiently applied to stereoselective and asymmetrically induced synthesis using chirally modified cobalt catalysts/ - so. 52 - se... 

The silica modified supported cobalt catalyst. Catalyst B, were tested in a Pilot Plant slurry bubble column reactor under realistic Fischer-Tropsch synthesis conditions and it... 

It was demonstrated that the production of clean waxy products (i.e. free of any cobalt contamination) during large scale slurry phase Fischer-Tropsch synthesis runs, was successfully effected with cobalt catalysts that were prepared on modified supports (i.e. supports displaying inhibited dissolution behaviour in aqueous environments). As an example, the silicon modification of alumina supports was discussed in detail. 

Oxo synthesis takes place in the folio wing conditions temperature between 130 and 180°C, pressure between 20 and 35.106 I i absolute, CO/H2 molar ratio between 1/1 and 1/12, residence time k o 5 min, catalyst 02 to 1 per cent weight in relation to propylene. The cobalt catalyst is still the most widely used for Oxo synthesis of propylene ( 45F, ICL PCXJK and Ruhrchemie). Since the normal aldehyde enjoys a much larger market than the iso-isomer, it is preferable to increase the n/iso ratio. This can be achieved partly by lowering the temperature and increasing the CO pressure. However, the catalyst can be modified for the same purpose. 

Asymmetric hydroformylation of prochiral olefins has been investigated both for the elucidation of reaction mechanism and for development of a potentially useful method for asymmetric organic synthesis. Rhodium and platinum complexes have been extensively studied, and cobalt complexes to a lesser extent. A variety of enantiopure or enantiomerically enriched phosphines, diphosphines, phosphites, diphosphites, phosphine-phosphites, thiols, dithiols, P,A-ligands, and P,5-ligands have been developed as chiral modifiers of rhodium and platinum catalysts. - " ... 

Cobalt compounds are useful chemical catalysts for the synthesis of fuels (Fi-scher-Tropsch process), the synthesis of alcohols and aldehydes from olefins, hydrogen and carbon monoxide at elevated temperatures and pressures ( oxo process , hydroformylation ). They are also used in petroleum refining and the oxidation of organic compounds. In the oxo process, cobalt carbonyl, Co2(CO)g, is employed or generated in situ. For the selective production of n-butanol from propylene, hydrogen and CO, an organophosphine-modified cobalt carbonyl complex is used as the catalyst. Cobalt salts are proven oxidation catalysts examples include the production of terephthalic acid by the oxidation of p-xylene, and the manufacture of phenol by the oxidation of toluene. 

Cobalt-containing alumina supported catalysts modified by a second metal have been parallel tested in the Fischer-Tropsch synthesis under pilot conditions. It has been observed that promotion of alumina supported Cocontaining catalysts by certain amounts of Pt leads to an increase in the formation of high molecular-weight hard hydrocarbons, so-called ceresins (77%). Also, it has been found that ceresin formation is strongly dependent on process conditions (pressure, temperature and space velocity). By parallel testing, the catalyst composition and process conditions for the selective production of ceresins from synthesis-gas have been determined and optimised. The physico-chemical properties have been studied by X-Ray, TEM, IR-spectroscopic, TPR and other methods. The synthesised catalysts are highly effective and stable. 

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