Dehydrogenation of hydrocarbons over a lumina -chromia and alumina-chromia-potassia catalysts prepared in various ways

Summary

• 1. An investigation was made of the effect of the method of preparation of alumina-chromia and alumina-chromia-potassia catalysts on their dehydrogenating and dehydrocyclizing activities.

• 2. The methods investigated for the preparation of catalysts affect the course of the dehydrogenation of isopentane least of all. In the dehydrocyclization of hexane the dependence is more marked. The dependence on the method of preparing the catalysts is still more marked in the dehydrogenation of cyclohexane.

• 3. The introduction of K₂O into alumina -chromia catalysts, however this may be effected, raises their activities and stabilities in the dehydrogenation of isopentane and cyclohexane and also in the dehydrogenation of hexane; it also reduces the yields of unsaturated hydrocarbons from hexane.

• 4. Of all the catalyst investigated, the best from the point of view of the obtaining of maximum yields of hexenes and the minimum yields of benzene is the alumina-chromia catalyst prepared by impregnation of alumina with ammonium dichromate solution (23% of unsaturated hydrocarbons and 16% of benzene).