Oxides chromium oxide

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. 

Ammonia production from natural gas includes the following processes desulfurization of the feedstock primary and secondary reforming carbon monoxide shift conversion and removal of carbon dioxide, which can be used for urea manufacture methanation and ammonia synthesis. Catalysts used in the process may include cobalt, molybdenum, nickel, iron oxide/chromium oxide, copper oxide/zinc oxide, and iron. 

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] ... 

Hydrogenolyses of carboxylic acids and esters to the corresponding aldehydes seems very attractive due to their simplicity. Copper chromites are the most widely used catalysts.15 Raney copper and zinc oxide-chromium oxide have also been used for this process.16-18 The hydrogenolysis of methyl benzoate to benzaldehyde was studied on various metal oxides at 300-350°C. ZnO, Zr02 and Ce02 presented high activities and selectivities (Scheme 4.8). 

Calcium oxide, Chromium oxide, Sodium chlorate MRH 10.7/67... 

Chromium(VI) oxide Chromium oxide (8,9) Chromium oxide (8,9) (1333-82-0)... 

Jones JG, Warner CG Ghronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks. Br J IndMed 29-. 69-m, 1972... 

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). 

The general cation distribution in the spinel structure of the iron oxide-chromium oxide catalyst (denoted Cr-Fe304 subsequently) is shown below ... 

As shown above, Eq. (5.2) is exothermic, and high temperatures are unfavorable for complete conversion. In the High Temperature Shift (HTS) conversion, the synthesis gas is passed through a bed of iron oxide/chromium oxide catalyst at around 400°C and a pressure of 25 to 28 bar. The CO content of the gas is reduced to about 3% (on a dry gas basis), and this is limited by the shift equilibrium at the actual operating temperature. The catalyst is not... 

Fatty alcohols are obtained by direct hydrogenation of fatty acids or by hydrogenation of fatty acid esters. Typically, this is performed over copper catalysts at elevated temperature (170°C-270°C) and pressure (40-300 bar hydrogen) [26], By this route, completely saturated fatty alcohols are produced. In the past, unsaturated fatty alcohols were produced via hydrolysis of whale oil (a natural wax occurring in whale blubber) or by reduction of waxes with sodium (Bouveault-Blanc reduction). Today, they can be obtained by selective hydrogenation at even higher temperatures (250°C-280°C), but lower pressure up to 25 bar over metal oxides (zinc oxide, chromium oxide, iron oxide, or cadmium oxide) or partially deactivated copper chromite catalysts [26],... 

Table IV. Polymerization over Nickel Oxide—Chromium Oxide on Silica—Alumina...

There are numerous other examples of the synthesis of quinones employing reagents such as nitric acid, manganese dioxide, salcomine/02, silver oxide, " chromium oxidants, >2 -47... 

Chromium oxide pigments chromium oxide chromium oxide hydrate green ... 

IRON OXIDE, CHROMIUM OXIDE, and NICKEL OXIDE FUME... 

Chromic Oxide. (Chromium Oxide, Chromium Sesquioxide, Chromium Hemitrioxide or Green Cinnabar) [Chrom (lll)-oxyd in Ger], Cr20, mw 152,02, dk-grn amorphous pdr or hex crysts, mp 1990 d5.2l insol in w, s 1 sol in ale can be prepd by heating Amm dichromace or Na dichromate with sulfur and washing out the Na sulfate (Refs 1, 2,3 5). 

Iron-chromium oxide catalysts, reduced with hydrogen-containing in the conversion plants, permit reactions temperatures of 350 to 380°C (high temperature conversion), the carbon monoxide content in the reaction gas is thereby reduced to ca. 3 to 4% by volume. Since, these catalysts are sensitive to impurities, cobalt- and molybdenum-(sulfide)-containing catalysts are used for gas mixtures with high sulfur contents. With copper oxide/zinc oxide catalysts the reaction proceeds at 200 to 250°C (low temperature conversion) and carbon monoxide contents of below 0.3% by volume are attained. This catalyst, in contrast to the iron oxide/chromium oxide high temperature conversion catalyst, is, however, very sensitive to sulfur compounds, which must be present in concentrations of less than 0.1 ppm. 

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