Nickel on kieselguhr

Dicyclohexylarnine may be selectively generated by reductive alkylation of cyclohexylamine by cyclohexanone (15). Stated batch reaction conditions are specifically 0.05—2.0% Pd or Pt catalyst, which is reusable, pressures of 400—700 kPa (55—100 psi), and temperatures of 75—100°C to give complete reduction in 4 h. Continuous vapor-phase amination selective to dicyclohexylarnine is claimed for cyclohexanone (16) or mixed cyclohexanone plus cyclohexanol (17) feeds. Conditions are 5—15 s contact time of <1 1 ammonia ketone, - 3 1 hydrogen ketone at 260°C over nickel on kieselguhr. With mixed feed the preferred conditions over a mixed copper chromite plus nickel catalyst are 18-s contact time at 250 °C with ammonia alkyl = 0.6 1 and hydrogen alkyl = 1 1. 

Supported palladium, zirconium-promoted cobalt on kieselguhr, or nickel on kieselguhr can be used under relatively mild conditions to effect reduction of the nitrile function without hydrogenating the ring. 

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. 

Arnett, R.L. and Buell, B.O. Magnetic separator for removing nickel-on-kieselguhr catalyst from conjugated diene solutions. US Patent (1956) 2,760,638. 

The catalysts used in these experiments included those already employed in the infrared measurements in addition to some others. The results are presented in Tables VI and VII along with some older measurements on Raney-nickel and a nickel-on-kieselguhr catalyst. These older measurements are slightly less accurate because the cyclohexane content of the reaction product was determined by mass spectrometry. The surface area of catalyst E was not determined hence, its reaction rates per unit of surface area could not be calculated. 

Nickel catalysts are universal and are widely used not only in the laboratory but also in the industry. The supported form - nickel on kieselguhr or infusorial earth - is prepared by precipitation of nickel carbonate from a solution of nickel nitrate by sodiiun carbonate in the presence of infusorial earth and by reduction of the precipitate with hydrogen at 450° after drying at 110-120°. Such catalysts work at temperature of 100-200° and pressures of hydrogen of 100-250 atm 43. ... 

Wright and Brandner84 have shown the reversible interconversion of aqueous solutions of these three dianhydrides in the presence of a nickel-on-kieselguhr catalyst under hydrogenating conditions. At the steady state, the product contains 57% of l,4 3,6-dianhydro-L-... 

Ethanedithiol has been prepared from ethylene dichloride or ethylene dibromide and alcoholic potassium hydrosulfide from ethylene dibromide and alcoholic sodium hydrosulfide from ethylene dichloride or ethylene dibromide and alcoholic sodium hydrosulfide under pressure from ethylene dibromide and thiourea and by the catalytic hydrogenation with cobalt trisulfide or nickel-on-kieselguhr of the mixture resulting from the reaction of ethylene and sulfur. The present method is a modification of one described by Mathias. ... 

It is important to note that the principal features of hydrogen chemisorption, which are summarized above, apply equally well to other adsorbents than zinc oxide, for instance to chromium oxide. A satisfactory theory therefore must not depend on specific properties of zinc oxide. In this connection let us recall the important experiments of Pace and Taylor (14) and Kohlschiitter (15), who found that the slow rates of chemisorption of hydrogen and deuterium on chromium oxide, zinc oxide-chromium oxide, and nickel on kieselguhr, were identical within experimental error. It would be interesting to perform such an experiment on zinc oxide because it permits one to make a decision on the nature of the slow activated step (16). 

When a nonacidic catalyst such as nickel on kieselguhr is used, demethylation of alkanes occurs almost exclusively.66 It is significant that the demethylation is very selective—a methyl group attached to secondary carbon is more readily cleaved off than is one attached to a tertiary, which in turn is more readily eliminated than one at a quaternary carbon. Demethylation of 2,2,3-trimethylpentane yielded product consisting of 90% 2,2,3-trimethylbutane, and only 7% 2,3- and 3% 2,2-dimethylpentane. 

Fig. i. Treatment of aromatic mineral oil fractions with nickel on kieselguhr catalysts and high pressure hydrogen. 

Tetrahydrofuryl) -propionic acid has been obtained from furylacrylic acid by catalytic reduction with platinum oxide,7 with nickel on kieselguhr,8 or with palladium black. ... 

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. 

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 reduction of aldols and ketols from the aldol condensation (method 102) is often a convenient route to branched 1,3-dio/s. Catalytic hydrogenation over platinum oxide, nickel-on-kieselguhr, and copper-chromium oxide has been used. Other procedures include electrolytic reduction and reduction by aluminum amalgam. 1,3-Diols may also be prepared by catalytic reduction of 1,3-diketones. Cleavage of the carbon-to-carbon and carbon-to-oxygen bonds accompanies this conversion. The effect of structure on the course of the reaction has been studied. ... 

Hydroquinone is reduced by a nickel-on-kieselguhr catalyst to cis- and /ra is-l,4-cyclohexanediols. Other eyelohexanediols and meth-oxycyclohexanols are formed from dihydric phenols and their monomethyl ethers. /S-Naphthol may be reduced in either ring, depending upon the catalyst and conditions. ... 

The nickel catalyst (about 50 wt% nickel on kieselguhr) was prepared by an ordinary precipitation method. Sodium carbonate solution was added to a slurry of kieselguhr and nickel nitrate solution at 70 °C and precipitate was obtained. This precipitate was washed with water thoroughly and then was dried at 105 C for 12 hrs, crushed to 60-150 mesh, calcined at 350 C for 4 hrs. This was activated with 100% hydrogen at 200, 300 and 350 "C for 4 hrs. These prepared catalysts were stored in nitrogen atmospheric bottle and desiccator. 

A nickel-on-kieselguhr catalyst containing about 70% of nickel in the reduced form, similar to the catalyst used by Haensel, was employed in the initial work. Since the removal of the methyl group from methylcyclohexane is considerably more difficult than removal of an unbranched methyl from a paraffin, the catalyst was pretreated for maximum activity by reducing in a stream of hydrogen for 15 hours at 700°F. 

Hydrogenation is also used for improving and accelerating separations. Drawert and coworkers [88, 89] employed hydrogenation for the determination of small amounts of ethanol in aqueous solutions and in blood. For the hydrogenation of alcohols to hydrocarbons, Raney nickel on Kieselguhr (1 10) was used as the catalyst at 160-200°C in a... 

Fig. 11. The hydrogenolysis of xylitol. Time dependence of the yields of the reaction (215°) with nickel on kieselguhr 1, initial xylitol 2, erythritol 3, glycerol 4, ethylene glycol 5, 1,2-propylene glycol.

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