Vanadium effect on HUSY zeolite deactivation during hydrothermal treatment and cyclohexane model reaction

In the present paper, vanadium was ion-exchanged and impregnated at different levels on a HUSY zeolite. The vanadium effect on hydrothermal deactivation and coke formation is discussed based on cyclohexane model reaction data combined with spectroscopic characterization techniques. Coke formation is affected by vanadium introduction. For all catalysts the presence of vanadium increased the coke amount comparing to HUSY. During coke deactivation, a portion of vanadium was reduced from 5+ to 4+. The dehydrogenation products (benzene and olefins) preferentially form on vanadium sites, react further on the zeolite acid sites, resulting in an increase in the coke formation and thus on catalyst deactivation.