The Effect of Addition of Potash to Nickel Chromite Catalysts

Abstract

Experiments are described on the dehydrogenation of butene-1 in the presence of steam, over three nickel chromite catalysts. These are: (a) pure nickel chromite, (b) nickel chrolnite pellets impregnated with potash from solution, and (c) a catalyst with potash added before the nickel oxide and chromium sesquioxide are combined. The oxidation state of the catalyst largely affects the products, for overreduction causes disruption of the hydrocarbons. The effect of the potash is to prevent this overreduction and thus t o improve selectivity t o butadiene. There is a difference between the behavior of catalysts with surface potash (type b) and those where the potash is distributed through the mass (type c). This difference is explained by the formation of large pores on reduction of type (c) catalysts.

Isomerization of butenes on some ZnO-, NiO- and Cr2O3- containing catalysts and the effect of controlled impurities and of potash additions

“…The relationship between the electrical properties of semiconducting meta oxides and their ability to catalyze chemical reactions has been the subject of considerable recent investigation.1-* In this laboratory the catalytic dehydrogenation of butenes to butadiene has been recently studied on several " pure " and " doped " metal oxides. [10][11][12] For the n-type semiconductor ZnO it was established that with large excesses of steam and in the temperature range 500 to 650°C, " doping " had a large effect on the rates of the reactions and to a lesser extent on the selectivity to butadiene formation. In particular, the catalytic dehydrogenation was strongly inhibited by doping with lithia.…”