High temperature pretreatment of Fe-silicalite for the ammoxidation of propane

Fe-silicalite with low concentration of iron was used in the study of the activation by high temperature nitridation (in the temperature range from 540 °C to 700 °C). Nitrided materials were characterized by means of FTIR and UV–Vis spectroscopy. It was found out, that by this high temperature pretreatment, Fe-silicalite undergoes structural changes – iron is extracted to extraframework positions and atom of nitrogen is incorporated into the zeolite structure (either as amide or as imide group), which was confirmed by FTIR spectroscopy. Catalytic performance of nitrided materials together with Fe-silicalite activated by hydrothermal pretreatment was studied and compared in the direct ammoxidation of propane. It was found out, that the nitrided materials reaches better results compared to sample activated in the steam. Selectivity as high as 34% at 32% conversion of propane was reached over the sample activated at 600 °C by nitridation. Nitrided material showed stable catalytic performance in the TOS study for 10 h.

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► Study of the nitridation of low concentrated Fe-silicalite.
► Nitridation temperature highly influences the structural changes in Fe-silicalite.
► Nitrided Fe-silicalite is active and stable material for propane ammoxidation.