Iron kieselguhr catalysts

Evaluation of commercial catalysts showed that nickel-on-kieselguhr catalyst is more active than nickel-on-alumina, iron, and ruthenium catalysts for cleanup of CO in IGTs hydrogasification process. Longer chained hydrocarbon formation is much less than expected for tests with iron and ruthenium catalysts. 

A study of the product selectivites of variously supported Co catalysts (kieselguhr, silica, alumina, bentonite, Y-zeolite, mordenite, and ZSM-5) was carried out by Bessel (37). AAdiereas the lower acidity supports such as silica and alumina produced mainly linear hydrocarbons, the acidic supports produced more branched products. At higher temperatures, the latter produced aromatics as well. The isomerization and aromatization are secondary, acid-promoted reactions of the FT olefins. This is then equivalent to a combination of the FT and the Mobil olefins to gasoline process. (With iron-based catalysts, this approach is unlikely to be successful because alkali promotion is essential and the alkali would neutralize the required acid sites on the zeolite support.) Calleja and coworkers (38) studied the FT performance of Co/HZSM-5 prepared by incipient wetness impregnation. Promotion with thorium, being basic, decreased the acidity of the zeolite and so less aromatics were formed and consequently more of the heavier hydrocarbons emerged from the reactor because of the depressed level of secondary reactions. 

The first promising catalyst was introduced by 1931 and contained a high proportion of nickel oxide supported on a mixture of thoria and kieselguhr. The convention widely used at the time was to describe composition as 100 parts nickel, 18 parts thoria, 100 parts kieselguhr. Catalysts made with cobalt rather than nickel were more effective but could not be considered eommercially at that time because cobalt was not available in suffieiently large quantities. The same problem had, of course, faced Haber and Boseh in the replaeement of osmium by iron oxide for the ammonia synthesis eatalyst. 

Palladium and platinum (5—10 wt % on activated carbon) can be used with a variety of solvents as can copper carbonate on siHca and 60 wt % nickel on kieselguhr. The same is tme of nonsupported catalysts copper chromite, rhenium (VII) sulfide, rhenium (VI) oxide, and any of the Raney catalysts, copper, iron, or nickel. 

Historical Development and Future Perspectives The Fischer-Tropsch process dates back to the early 1920s when Franz Fischer and Hans Tropsch demonstrated the conversion of synthesis gas into a mixture of higher hydrocarbons, with cobalt and iron as a catalyst [35, 36], Some 20 years earlier, Sabatier had already discovered the reaction from synthesis gas to methane catalyzed by nickel [37]. The FTS played an important role in the Second World War, as it supplied Germany and Japan with synthetic fuel. The plants used mainly cobalt catalysts supported on a silica support called kieselguhr and promoted by magnesia and thoria. 

Hydrogenation of cinnamaldehyde to 3-phenylpropionaldehyde over palladium catalyst may be accompanied by the formation of 3-phenyl-1-propanol and propyl-benzene,218 although the formation of 3-phenylpropionaldehyde usually predominates.219,220 The composition of the products are widely affected by the nature of palladium catalysts, solvents, supports, and additives.216,221 The hydrogenation over Pd-Al203 in ethanol or over Pd-kieselguhr in acetic acid gave 3-phenylpropionalde-hyde quantitatively at room temperature and atmospheric pressure. The addition of a 1 1 ratio of ferrous chloride to palladium also resulted in quantitative formation of 3-phenylpropionaldehyde in the hydrogenation over 5% Pd-C in methanol.221 This result was contrasted with those obtained with platinum oxide where iron additives led... 

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 kieselguhr, cobalt-thoria on kieselguhr, and cemented iron oxide. The main products are C5 to Cn aliphatic hydrocarbons the aromatics content can be varied by varying the process conditions. 

Russian workers have demonstrated that cyclooctane can be dehydrogenated to crs-bicyclo[3.3.0]octane when passed in the gas phase over a heated catalyst such as platinum on carbon, platinum and iron on carbon, or nickel on Kieselguhr.93-98 Unfortunately, the yields are highly variable (0.5—70 %) and details of these processes are scanty. Perhaps more promising is their discovery that n-octane and its cyclodehydrogenation product n-propylcyclopentane can be converted to the bi-cyclic hydrocarbon under comparable conditions. 

The traditional treatment of nitrobenzene (1) with iron and acid, called Bechamp reduction, was employed almost exclusively in the production of aniline (2) and many aromatic amines until the 1960s1,2 (Scheme 1). The reduction is straightforward, and can also be achieved by catalytic hydrogenation, sodium sulfide reduction and zinc reduction with caustic soda. Nitrotoluenes and nitroxylenes are hydrogenated under pressure over a nickel catalyst supported on kieselguhr. The sulfide reduction is useful in selective reduction, such as of m-dinitrobenzene to m-nitroaniline. 

The modem process uses a potassium-sulfate-promoted vanadium(V) oxide catalyst on a silica or kieselguhr support. The SO2 is obtained either by burning pure sulfur or by roasting sulfide minerals (p. 651) notably iron pyrite, or ores of Cu, Ni and Zn during the production of these metals. On a worldwide basis about 65% of the SO2 comes from the burning of sulfur and some 35% by the roasting of sulfide ores but in some countries (e.g. the UK) over 95% comes from the former. 

Meyer and Bahr (21) carried out similar experiments with iron-kiesel-guhr catalysts. The type of catalyst support, which was very important in the case of cobalt and nickel catalysts, showed no pronounced influence in the case of iron catalysts. Iron catalysts produced from ferro salts and kieselguhr were not active, while iron catalysts produced from ferri salts and kieselguhr yielded comparatively good results. 

Under the conditions of the Fischer-Tropsch synthesis, i.e., at 200° and atmospheric pressure, cobalt, and to a lesser extent iron, were suitable catalysts for the synthesis of higher hydrocarbons. Nickel, which has a much greater hydrogenating action than cobalt or iron promotes the formation of methane and could be used for synthesis of higher hydrocarbons only by "diluting with kieselguhr. 

The physical structure, which can be changed by suitable methods of catalyst manufacturing, is. of decisive importance (promoters high-melting oxides supports kieselguhr of cobalt and nickel catalysts pretreatment low-temperature reduction which limits the size of the crystals, or carbon monoxide treatment of iron catalysts which increases the surface by breaking up the structure with carbon). 

Nickel, cobalt, and iron catalysts are cmnmonly used for the Fischer-Tropsch s thesis. Nickel catalysts have been prepared by precipitation from a nitrate solution with potassium carbonate in the presence of thoria and kieselguhr in the proportions lOONiilSThOzilOO kieselguhr. It is not desirable to employ nickel catalysts at low temperatures and elevated pressures because the formation of nickel carbonyl is excessive. In the temperature range of 170-220°C at. low pressures, both liquid and gaseous products are obtained. As the temperature is increased to 300-350°C and the pressure increased to 300-400 psi, nickel catalysts produce only methane. Thus, these catal nsts can be used for making a gas from coal comparable in heating value to natural gas. 

After washing, the filter cake is repulped and enough potassium hydroxide added so that after a subsequent additional filtration 3.0-3.5 g. KOH/100 g. iron are retained. This is achieved if the concentration of KOH in the mother liquor is about 6 g./l- After impregnation, the suspension was filtered and the filter cake dried at 110° C. and subsequently crushed and screened. This procedure yields a catalyst containing Fe Cu CaO kieselguhr in the proportions 10 5 10 30 parts by weight. 

For example, zeolites are used in different processes, but especially in the catalytic and thermal cracking to produce gasoline from petroleum. Another example is a well-known powdered catalyst of iron-silica (kieselguhr) promoted with K, applied in the Fischer-Tropsch synthesis to obtain hydrocarbons, in a wide range of light hydrocarbons, gasoline, and diesel. 

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