Chromium aluminum oxid Copper chromite

The search is on for catalysts to replace those containing toxic heavy metals. The addition of hydrogen chloride to acetylene to form vinyl chloride is catalyzed by mercuric chloride. Rhodium (III) chloride on activated carbon works just as well and is much less toxic 97 It should be tried also in other addition reactions of acetylene as well as in trans-esteriflcation reactions of vinyl acetate. The reduction of 2 ethyl-2-hexenal to 2-ethylhexanol can be catalyzed by a mixture of copper, zinc, manganese, and aluminum oxides in 100% yield.98 This is said to be a replacement for carcinogenic copper chromite. In Reaction 4.15, the amount of toxic chromium(II) chloride has been reduced from stoichiometric to catalytic (9-15 mol% chromium(II) chloride) by the addition of manganese metal.99... 

Fio. 11. The rate constant logarithm aa a function of the temperature reciprocal in the oxidation of iso-octane over various catalysts 1—copper chromium, 2—copper chromite, 3—platinum, 4—copper aluminum and iron-aluminum, 6—silver manganate, 6—iron-chromium, 7—magnesium chromite, 8—copper chromium with addition of PbO. 

Hydrogenation is generally carried out at tanperatures of 250-280°C and pressures of 20-25 MPa. Catalysts include zinc oxide in conjunction with aluminum oxide, chromium oxide, or iron oxide, and possibly, other promoters copper chromite whose activity has been reduced by the addition of cadmium compounds and cadmium oxide on an alumina carrier. Selective hydrogenation can also be carried out in a homogenous phase with metallic soaps as catalysts. 

The activity of NiO has been studied by Wagner and Hauffe (47) and others (22,49,50). Catalytic activity of this oxide is enhanced considerably by the addition of manganese dioxide. For the simple oxides, the activity decreases in the following series Mn02 > C02O3 > NiO > CuO (48). The catalysts containing nickel oxide are promoted by the addition of oxides of iron, copper, aluminum, and chromium. Iron, nickel, and cobalt chromites, as catalysts for the oxidation of CO, were investigated by Lory (30). 

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