Causes of catalyst deactivation during quinoline hydrodenitrogenation

The current work involves determining the causes of deactivation due to hydrotreating pyridinic compounds. Quinoline was chosen as the model compound for this study because it represents a type of nitrogen compound present in coal-derived materials, and a hydrodenitrogenation (HDN) reaction network has been proposed for this compound. In the proposed reaction scheme, at low temperatures, quinoline is hydrogenated to 1,2,3,4-tetrahydroquinoline (PyTHQ). PyTHQ is cracked to o-propylaniline (OPA), and then the nitrogen is removed, as ammonia, to give propylbennzene (PBz). At high temperatures, the hydrogenation of quinoline to 5,6,7,8-tetrahydroquinoline (BzTHQ) also becomes important. BzTHQ is further hydrogenated to decahydroquinoline (DHQ) which is then cracked and denitrogenated to yield mostly propylcyclohexane (PCH). TyTHQ can also be hydrogenated to DHQ and OPA can also be hydrogenated and denitrogenated to PCH. The initial work reported here on the causes of deactivation due to hydrogenating quinoline will cover the impact of process conditions on deactivation and the determination of the effects of the reaction scheme intermediates and products on deactivation.