Mechanism of coke influence on the catalytic activity of FeZSM-5 in the reaction of benzene oxidation into phenol

The influence of coke formation in the reaction of benzene oxidation by nitrous oxide into phenol on the catalytic activity and concentration of iron-containing active sites (alpha -sites), which are stabilized in the microporous structure of FeZSM-5 zeolite, is studied. The deactivation by coke is explained by the poisoning of alpha -sites, whose concentration decreases linearly with an increase in the coke content, rather than by the blocking of zeolite pores. The activity per one alpha -site remains unchanged. This fact indicates the absence of diffusion limitations associated with coke formation. The toxicity of coke for the alpha -sites is determined. The coke amount equivalent to 100-120 benzene molecules is shown to result in the deactivation of one active site.