Two-dimensional mica nanosheets supported Fe nanoparticles for NH3 decomposition to hydrogen

Abstract

Two-dimensional mica nanosheets (MS) are employed as support for preparation of Fe/MS catalysts by three different methods namely homogeneous precipitation (HP), impregnation (IM), and deposition precipitation (DP) methods. Their catalytic performances for ammonia decomposition are tested, and their physicochemical properties are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray photoelectron spectroscopy, ammonia/hydrogen temperature-programmed desorption, and N2 sorption techniques. The catalytic results show that the preparation methods would remarkably affect the catalytic performance of Fe/MS catalysts, and the Fe/MS catalysts prepared by HP method exhibit the highest catalytic activity. It is revealed that the coexistence of three types of Fe species including Fe3+, Fe2+ and Fe0 in the reduced Fe/MS catalysts are responsible for the ammonia decomposition. The excellent catalytic performance of Fe/MS-HP catalyst is attributed to the highly dispersed Fe species, layered structure of mica, and strong metal-support interactions between Fe and mica. Stability testing shows that the 5%Fe/MS-HP catalyst exhibits high catalytic stability, suggesting a very promising catalyst in ammonia decomposition.