The effect of alkali metal oxides on the activity, selectivity and the phase composition of binary catalysts based on A1₂O₃

Summary

• 1. The variation of the general and specific activity and selectivity of NiO-Al₂O₃-, Fe₂O₃-Al₂O₃-Cr₂O₃-Al₂O₃-, and ZrO₂-Al₂O₃-catalysts in the decomposition reaction of absolute isopropyl alcohol was determined at 290–350°C. The phase composition and values of the specific surface with the addition of 2–4% of K₂O and Na₂O were also obtained.

• 2. These additives have the following effects: they reduce the general activity of the catalysts considerably due to the suppression of the dehydrating activity; they rapidly alter the selectivity of the catalysts due to the increase or the emergence of dehydrogenating activity; facilitates the crystallization of amorphous phases in the catalysts; stabilizes the γ-modification of the oxides of Fe and Al i.e., of a spinel type lattice, and in the case of polymorphous components of the catalyst may change the character of the crystallization i.e., lead to a phase transformation.

• 3. The natural catalytic activity with heterogeneous decomposition of isopropyl alcohol has been obtained; a) with activated carbon, b) with potassium aluminate and c) with KOH.