Evaluation of M‐xylene ammoxidation at bench‐scale operation in the presence of V2O5/Γ‐Al2O3 catalyst

Abstract

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 25 mm i.d. using 200 g 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.