ACTIVE-SITES AND INTERMEDIATES FOR ISOMERIZATION AND CRACKING OF CYCLOHEXANE ON HY

Initiation of both isomerization and cracking reactions of cyclohexane on HY at 400°C occurs at Brønsted sites. The absence of molecular hydrogen as a product indicates that protonation of the feed molecule occurs, and the resulting carbonium ion can rearrange through a cracking-realkylation process, or undergo ring cleavage leading to acyclic products. No direct evidence was obtained which would indicate the existence of a chain mechanism proceeding through cyclic carbenium ion intermediates. These observations support a previously proposed mechanism for initiation of cracking of linear paraffins at Brønsted sites. © 1990.