Evaluation of M-xylene ammoxidation at bench-scale operation in the presence of V₂O₅/Γ-AL₂O₃ catalyst

A bench-scale ammoxidation reaction of m-xylene was evaluated in the presence of V₂O₅/γ-Al₂O₃ catalyst. The experiment was performed in a packed-bed reactor with 25mm i.d. using 200g of catalyst. To alleviate sudden temperature hikes during ammoxidation, molten salt system was carefully built in the outer part of the reactor in a jacket-type. Higher value of heat capacity of molten salt led to the stabilized reaction temperature within tolerable ranges without significant deactivation of catalytic activity. Isophthalonitrile (IPN) was a main product to compare reaction performance, while m-tolunitrile, even hardly observed in a lab-scale experiment, was a noticeable by-product in this study. Reaction parameters include reaction temperature, oxygen to m-xylene ratio, NH₃ to m-xylene ratio, and gas hourly space velocity. The selectivity of IPN over m-tolunitrile was clearly improved when reaction temperature was raised from 320 to 380 °C. For a long-term test, the reaction was evaluated in the period of one year. The catalyst was characterized before and after the long-term experiment and its changes were analyzed by N₂-physisorption, SEM, XRD and XPS.