Promotional effect of Au on Fe/HZSM-5 catalyst for methane dehydroaromatization

The effects of noble metals (Au, Ag, Pt, and Rh) on the Fe/HZSM-5 catalyst were investigated for the methane dehydroaromatization (MDA) reaction. Notably, the Au-promoted Fe/HZSM-5 catalyst exhibited the best performance, with improved catalytic stability. The presence of Au intensively enhanced the carburization degree of the Fe species by increasing the dispersion of Fe and promoting the dehydrogenation of methane. Correspondingly, X-ray diffraction patterns and X-ray photoelectron spectroscopy analysis of the spent catalysts confirmed that the clear presence of iron carbide for the Fe-Au catalyst, which resulted from the increased the carburization degree of Fe species. In addition, Au atoms deposited on Brönsted acid sites provided an adequate amount of acidity, leading to reduced coke formation. All these observations suggest that Au is a new and an efficient promoter for Fe/HZSM-5 catalyst with the MDA reaction.