Chromium oxides hydrogenation catalyst

Copper chromite has been made by the ignition of basic copper chromate at a red heat and by the thermal decomposition of copper ammonium chromate. The procedure given here is a modification of the latter method in which barium ammonium chromate is also incorporated. Copper-chromium oxide hydrogenation catalysts have also been prepared by grinding or heating together copper oxide and chromium oxides, by the decomposition of copper ammonium chromium carbonates... 

H. Adkins, Reactions of Hydrogen with Organic Compounds over Chromium Oxide andNickel Catalysts, University of Wisconsin Press, Madison, 1946. 

Treatment of butadiene or 1,4-butanediol with hydrogen sulfide over an alumina catalyst, or an iron sulfide/alumina catalyst, leads to the formation of thiophene. This method has been more useful in the benzothiophene series. Styrene with four equivalents of hydrogen sulfide, when passed over an iron sulfide/aluminum oxide catalyst at 600 °C for 20 seconds, gave a 60% mole conversion to benzo[6]thiophene (47JA2008). Similar treatment of ethylbenzene over a chromium oxide-alumina catalyst gave an 18% yield of benzo[6]thiophene, accompanied by the evolution of hydrogen (48JA2495). 

The hydrogenation of an unsaturated ester to an unsaturated alcohol may be possible over zinc-chromium oxide as catalyst, although the catalyst is known to be much less active for the usual ester hydrogenations than copper-chromium oxide. Ethyl or butyl (eq. 10.25) oleates were hydrogenated to octadecenol in yields of over 60% with a zinc-chromium oxide at 280-300°C and 20 MPa H2.16 The butyl ester was much preferred to the ethyl ester, since it was difficult to separate the ethyl ester from the alcohol product because of their similar boiling points. 

Ni-kieselguhr. iV-Butylpiperidine was obtained in a 78.7% yield when pyridine was hydrogenated in butyl alcohol at 220°C and 8.8 MPa of initial hydrogen pressure (eq. 12.15).22 The reaction was also studied using Raney Ni and copper-chromium oxide as catalysts, resulting in somewhat lower yields of N-butylpiperidine.24... 

Hydrogenation of flavone or flavanol over copper-chromium oxide at 145-165°C resulted in the formation of o-hydroxy-l,3-diphenylpropane as the chief product, which was isolated in yields of about 50%, and in no case flavan was found in a yield greater than 34%. In hydrogenation of flavonol (3-hydroxyflavone) (70) over copper-chromium oxide, the catalyst was deactivated rapidly because of a strong acidic character of flavonol, and only 17% of 3,4-dihydroxyflavan was obtained. Probably for a similar reason, quercetin (71) was not hydrogenated at all in dioxane over copper-chromium oxide or over Raney Ni, even at 200°C.233... 

Hydrogenation Copper chromite (Lazier catalyst). Copper chromium oxide (Adkins catalyst). Lindlar catalyst (see also Lithium ethoxyacetylide, Malealdehyde, Nickel boride). Nickel catalysts. Palladium catalysts. Palladium hydroxide on carbon. Perchloric acid (promoter). Platinum catalysts. Raney catalysts, Rhenium catalysts. Rhodium catalysts. Stannous chloride. Tributylborane. Trifluoroicetic acid, Tris (triphenylphosphine)chlororhodium. 

Groeneveld C, Wittgen PPMM, van Kersbergen AM, et al Hydrogenation of olefins and polymerization of ethene over chromium oxide/silica catalysts. I. Preparation and structure of the catalyst, J Catal 59(2) 153—167, 1979. 

Hydrogenations with coppcr-chromium oxide catalyst are usually carried out in the liquid phase in stainless steel autoclaves at pressures up to 5000-6000 lb. per square inch. A solvent is not usually necessary for hydrogenation of an ester at 250° since the original ester and the alcohol or glycol produced serve as the reaction medium. However, when dealing with small quantities and also at temperatures below 200° a solvent is desirable this may be methyl alcohol, ethyi alcohol, dioxan or methylcyc/ohexane. 

Aromatic rings in lignin may be converted to cyclohexanol derivatives by catalytic hydrogenation at high temperatures (250°C) and pressures (20—35 MPa (200—350 atm)) using copper—chromium oxide as the catalyst (11). Similar reduction of aromatic to saturated rings has been achieved using sodium in hquid ammonia as reductants (12). 

Methanol Synthesis. Methanol has been manufactured on an industrial scale by the cataly2ed reaction of carbon monoxide and hydrogen since 1924. The high pressure processes, which utili2e 2inc oxide—chromium oxide catalysts, are operated above 20 MPa (200 atm) and temperatures of 300—400°C. The catalyst contains approximately 72 wt % 2inc oxide, 22 wt % chromium (II) oxide, 1 wt % carbon, and 0.1 wt % chromium (VI) the balance is materials lost on heating. 

Table IV presents the results of the determination of polyethylene radioactivity after the decomposition of the active bonds in one-component catalysts by methanol, labeled in different positions. In the case of TiCU (169) and the catalyst Cr -CjHsU/SiCU (8, 140) in the initial state the insertion of tritium of the alcohol hydroxyl group into the polymer corresponds to the expected polarization of the metal-carbon bond determined by the difference in electronegativity of these elements. The decomposition of active bonds in this case seems to follow the scheme (25) (see Section V). But in the case of the chromium oxide catalyst and the catalyst obtained by hydrogen reduction of the supported chromium ir-allyl complexes (ir-allyl ligands being removed from the active center) (140) C14 of the...

Hydrogenation of Fatty Acid Methyl Esters The hydrogenolysis of fatty acid methyl esters into the corresponding fatty alcohols and methanol is performed at 200-300°C and a H2 pressure of 200-300 bar with the aid of copper oxide/chromium oxide catalysts (Adkins catalysts). Three different procedures are applied [39 a-c] ... 

Some more recent processes have been developed which involve direct hydrogenation of the oil to the fatty acid and 1,2-propane diol. These high-temperature (>230 °C) and high-pressure processes generally use a copper chromium oxide catalyst. 

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