Kieselguhr catalyst support

Nickel. As a methanation catalyst, nickel is presently preeminent. It is relatively cheap, it is very active, and it is the most selective to methane of all the metals. Its main drawback is that it is easily poisoned by sulfur, a fault common to all the known active methanation catalysts. The nickel content of commercial nickel catalysts is 25-77 wt %. Nickel is dispersed on a high-surface-area, refractory support such as alumina or kieselguhr. Some supports inhibit the formation of carbon by Reaction 4. Chromia-supported nickel has been studied by Czechoslovakian and Russian investigators. 

Hexane-1,6-diol was found to undergo an oxidation-cyclization process at elevated temperatures (250 °C) in the presence of a Cu-Cr catalyst supported on kieselguhr to yield 2,3,4,5-tetrahydrooxepin (68) (65JOC335). The final stage of the latter reaction involves a dehydration of the hemiacetal 2-hydroxyoxepane (75) as indicated in equation (38). An alternative type of base-induced cyclization (equation 39) involving intramolecular nucleophilic attack has been used in the synthesis of 4-ethoxycarbonyI-2,3,6,7-tetra-hydrooxepin (153) (73JOC1767). 

The solid catalyst is a calcined mixture of phosphoric acid and kieselguhr. The kieselguhr acts as a catalyst support but it also enters into chemical combination with the phosphoric acid. Although several other catalysts were developed earlier, and some subsequently, the acid-and-kieselguhr solid catalyst excels all others. 

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. 

Catalytic tests in sc CO2 were run continuously in an oil heated flow reactor (200°C, 20 MPa) with supported precious metal fixed bed catalysts on activated carbon and polysiloxane (DELOXAN ). We also investigated immobilized metal complex fixed bed catalysts supported on DELOXAN . DELOXAN is used because of its unique chemical and physical properties (e. g. high pore volume and specific surface area in combination with a meso- and macro-pore-size distribution, which is especially attractive for catalytic reactions). The effects of reaction conditions (temperature, pressure, H2 flow, CO2 flow, LHSV) and catalyst design on reaction rates and selectivites were determined. Comparative studies were performed either continuously with precious metal fixed bed catalysts in a trickle bed reactor, or discontinuously in stirred tank reactors with powdered nickel on kieselguhr or precious metal on activated carbon catalysts. Reaction products were analyzed off-line with capillary gas chromatography. 

With a DELOXAN supported palladium complex catalyst, DELOXAN HK I, the linoleate selectivity is further increased. In comparison to the commercial batch hydrogenation with a nickel on kieselguhr catalyst, the DELOXAN supported palladium complex catalyst in combination with sc CO2 as a solvent gives higher space-time-yields, a higher linoleate selectivity and a significantly decreased cis/trans isomerization rate. 

DELOXAN AP II supported platinum catalysts in sc CO2 are less active than DELOXAN AP II supported palladium catalysts, but they show an improved linoleate selectivity and a significantly lower cis-trans isomerization rate. The overall yield of undesirable trans fatty acids is 7.5 GC area-% in the edible oil hardening with a DELOXAN AP II supported 2 wt. % platinum catalyst. In a batch hydrogenation using the commercial powdered nickel on kieselguhr catalysts the undesirable trans fatty acid content was determinded to 40 percent. 

Kehoe and Butt [J. P. Kehoe and J. B. Butt, AIChE /., 18 (1972) 347] have reported the kinetics of benzene hydrogenation of a supported, partially reduced Ni/kieselguhr catalyst. In the presence of a large excess of hydrogen (90 percent) the reaction is pseudo-first-order at temperatures below 200°C with the rate given by ... 

The effect of alkali metal on the catalytic gasification of rice straw over nickel catalysts supported on kieselguhr... 

Abstract Rice straw was catalytically gasified over nickel catalysts supported on kieselguhr. This has been done by varying the content of alkali carbonate, lithium metal (3-20wt%) and various sodium compounds. In the case which alkali metal carbonates were separately added with nickel catalyst, conversion to gas was increased in the following order of Li< Cs< Kalkali metals were used to as co-catalyst by impregnation method, gas formation was increased in the following order Cs< tC a< Li. These results showed same aspects with TPR patterns. 

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. 

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. 

In an effort to obtain a less temperature-sensitive system, lower nickel content catalysts were prepared on an alumina support and tested for demethylation activity. The first, Preparation A, with a nominal nickel content of 50 wt % was activated at 700°F in a slow stream of hydrogen at atmospheric pressure for 16 hours. This catalyst was tested at conditions similar to those employed with the nickel-kieselguhr catalyst reported above. The results are given in Table II. 

Orito et al. found that small amounts (1%) of noble metal additives, like Ru, Pt, or Pd, in Ni catalysts supported on Kieselguhr significantly increased enantioselectivity in the liquid phase hydrogenation of MAA. Therefore, it was of interest to study bimetallic catalysts based on Pd and mixed with Cu and Ni with greater concentrations of Pd than 1% (see works of Klabunovkii s group )... 

The conditions of preparation of catalysts from its precursor Ni-salts affect the crystallite size and crystallite size distribution. Therefore small amounts of the additives, such as, Pt or Pd salts, have a favorable effect during reduction of the catalysts and the process of its formation Orito et al. were first to show that enantioselectivity in the hydrogenation of MAA into MHB over Ni catalysts supported on Kieselguhr and modified with (2.R,3.R)-tartaric acid can be increased from 53% to 62% after including in the composition of the catalyst 1% of a noble metal, the best being Pt or Pd. Loading of the metal on Kieselguhr is of importance only the... 

Figure 1.4 Silica materials that have been used catalyst support, (a) Natural silica, kieselguhr ( 20 m g ) (b) silica gel ( 500 m g )l and (c) ordered mesoporous silica, SBA-15 ( -500 m g- ).

In industrial practice, although some copper catalysts have been used, it is customary to use dry or wet reduced nickel catalysts supported on a natural earth such as kieselguhr and suspended in an hydrogenated fat, usually hardened palm or soybean oil. The nickel content of the commercial catalyst is between 17 and 25% and a similar amount of earth is incorporated. 

The plant at which you are employed currently manufactures cumene in Unit 800 by a vapor-phase allq/ lation process that uses a phosphoric acid catalyst supported on kieselguhr. Plant capacity is on the order of 90,000 metric tons per year of 99 wt% purity cumene. Benzene and propylene feeds are brought in by tanker trucks and stored in tanks as a liquid. 

R-801 shell-and-tube packed-bed with phosphoric acid catalyst supported on kieselguhr Boiler feed water in shell to produce high-pressure steam Reactor volume = 6.50 m, heat exchange area = 342 m ... 

Asbestos Pumice Kieselguhr (infusorial earth) Bauxite/titanium dioxide Carbon Metal salts, e.g., MgSOt MgCl2 Quartz lumps Contact process. Deacon process, hydrogenation catalyst supports. Fat hardening, hydrogenation catalyst support. Dehydration reactions, catalyst support and cracking catalyst. Support for precious metals. Contact process olefin polymerization. Used as an inert support for catalysts and also as a physical support at the bottom of a catalyst bed. 

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. 

For many years after the fat hydrogenation process was introduced, manufacturers made their own catalysts when they were needed. Then, gradually, the nickel salt producers began to make the catalysts for operators. This improved quality and ensured more efficient operation. By 1928 the best catalyst supports were found to be kieselguhr or fuller s earth,charcoal, " and complex silicates such as permutite. Many other practical ideas were introduced such as ... 

Trimethylacetaldehyde passed at 300° under Ng through H3P04-on-Ghromosorb W (a kieselguhr product) — 3-methyl-2-butanone. Y almost 100%. F. e., mostly isomerization of ketones, and f. catalyst supports, s. W. H. Gorkern and A. Fry, Am. Soc. 89, 5888 (1967). 

The classic catalyst consists of Co-Th02-MgO mixtures supported on Kieselguhr (see Ref. 269) group VIII metals, especially Ni, generally are active,... 

Benzene-Based Catalyst Technology. The catalyst used for the conversion of ben2ene to maleic anhydride consists of supported vanadium oxide [11099-11-9]. The support is an inert oxide such as kieselguhr, alumina [1344-28-17, or sUica, and is of low surface area (142). Supports with higher surface area adversely affect conversion of benzene to maleic anhydride. The conversion of benzene to maleic anhydride is a less complex oxidation than the conversion of butane, so higher catalyst selectivities are obtained. The vanadium oxide on the surface of the support is often modified with molybdenum oxides. There is approximately 70% vanadium oxide and 30% molybdenum oxide [11098-99-0] in the active phase for these fixed-bed catalysts (143). The molybdenum oxide is thought to form either a soUd solution or compound oxide with the vanadium oxide and result in a more active catalyst (142). 

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