Copper magnesia catalyst

It may be mentioned here that the first example in which the author tried to apply the principle contained in this paper was on the hydrolysis of methanol (19) (cf. p. 315) with a copper-magnesia catalyst. This reaction is, of course, heterogeneous. 

Silica from three sources was added to an iron- copper-magnesia catalyst and the activity for the conversion of syngas to middle distillate for the catalysts with and without silica was studied in a 150 ml Fixed Bed Single Tube Reactor. The study revealed that silica additive changes the activity and this change depends on the source of silica and the associated ingradients. 

Fig. 14. Dependence of the logarithm of the frequency factor upon the energy of activation when different additive components are combined with magnesia-chromia and copper-chromia catalysts.

In support of that explanation, X-ray analysis of the catalyst after use indicated the presence of MgO. Hence, the catalytically active phase was finely divided copper in intimate contact with magnesia, quasi as carrier. The same phenomenon was observed with the Zintl-phase alloys of silver and magnesium. Such catalysts were then deliberately prepared by coprecipitation of copper and silver oxides with magnesium hydroxide, followed by dehydration and reduction. Table I shows that these supported catalysts had the same activation energies as those formed by in situ decomposition of copper and silver alloys with magnesium. 

The reactions studied were the extensive oxidation of isooctane and of ethylene over magnesia-chromia and copper-chromia and of ethylene over tungstic oxide. The catalysts used in the oxidation of isooctane differed greatly with respect to their activities and the observed value of activation energy and frequency factor, as is indicated in Table V. 

Catalytic reductions have been carried out under an extremely wide range of reaction conditions. Temperatures of 20 C to over 300 C have been described. Pressures from atmospheric to several thousand pounds have been used. Catal3rsts have included nickel, copper, cobalt, chromium, iron, tin, silver, platinum, palladium, rhodium, molybdenum, tungsten, titanium and many others. They have been used as free metals, in finely divided form for enhanced activity, or as compounds (such as oxides or sulfides). Catalysts have been used singly and in combination, also on carriers, such as alumina, magnesia, carbon, silica, pumice, clays, earths, barium sulfate, etc., or in unsupported form. Reactions have been carried out with organic solvents, without solvents, and in water dispersion. Finally, various additives, such as sodium acetate, sodium hydroxide, sulfuric acid, ammonia, carbon monoxide, and others, have been used for special purposes. It is obvious that conditions must be varied from case to case to obtain optimum economics, yield, and quality. 

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