Activation of an aluminoplatinum catalyst in the reactions of isomerization and hydrogenolysis of hydrocarbons by high-temperature treatment with hydrogen

Abstract

1. The change in the activity of an aluminoplatinum catalyst (0.3% Pt) was investigated after its treatment (500–550°) with hydrogen, purified of oxygen and water, as well as with nitrogen (420°), containing ∼0.5% oxygen. 2. As a result of high-temperature treatment of the catalyst with hydrogen, the degree of isomerization of cyclohexane and n-hexane, as well as the hydrogenolysis of methylcyclopentane, very sharply increases. Treatment with nitrogen containing oxygen deactivates the catalyst in reactions of isomerization and hydrogenolysis of hydrocarbons and activates it in the hydrogenation of benzene. 3. Purification of the catalyst from oxygen and water by high-temperature treatment with hydrogen causes a change in the direction of hydrogenolysis of methylcyclopentane: although on a catalyst treated with hydrogen at 350–420° the five-membered ring of methylcyclopentane is cleaved primarily at the bonds far distant from the substituent, with the formation of isohexanes, after treatment of the catalyst with hydrogen at 550°, predominant cleavage of the five-membered ring occurs, at the bonds closestto the substituent,forming n-hexane.