The effect of support morphology on the activity of HZSM-5-supported molybdenum catalysts for the aromatization of methane

International audienceThe aromatization of methane was investigated over Mo2C supported on several HZSM-5 zeolites with different morphologies and Si/Al ratios. X-ray diffraction, elemental analyses, X-ray photoelectron spectroscopy, 27Al NMR spectroscopy, nitrogen adsorption, and scanning electron microscopy were used to characterize the supports. Support morphology was observed to play a crucial role in this reaction, which was studied under conditions in which actual rates could be compared. Although rates did not vary linearly either with the total number of the acid sites or with the external surface area, turnover frequencies of the surface acid sites, calculated using the Si/Al ratios determined from XPS measurements, were observed to vary linearly with the external surface area

Activities of MFI-Supported Rhenium Catalysts for the Aromatization of Methane: Effect of Cationic Form of the Inorganic Carrier

International audienceMFI type inorganic carrier was used in two different cationic forms, hydrogen and calcium respectively. MFI-supported molybdenum and rhenium catalysts were prepared. The activities of the catalysts were compared for the aromatization reaction of methane. Higher activity values were attained with the catalysts supported on HZSM-5. Aromatics were also observed with the catalysts supported on CaZSM-5, despite their deficiency in acid sites. Highly dispersed rhenium is expected to be formed with the use of the inorganic carrier in calcium form. On the other hand, lower reaction rates were observed with rhenium supported on CaZSM-5, in spite of the improved dispersion of the active rhenium species on this catalyst. This was interpreted in terms of the critical role of the acid sites in the conversion of methane to aromatics, compared to the improved dispersion of the active metal