Conversion of methanol into light olefins over ZSM-5 zeolite: Strategy to enhance propene selectivity

Four ZSM-5 zeolite materials with varying crystal size, acid site density and morphology were prepared, characterized by BET, XRD, SEM, FT-IR, H/D exchange and n-hexane cracking experiments and tested as catalysts for the Methanol to Olefins (MTO) reaction at 350 °C, WHSV = 1.8 g/gh under atmospheric pressure.Optimal propene to ethene ratios (>5) were obtained over a material prepared via the fluoride route. Its superior selectivity was tentatively ascribed to its low density of strong acid sites in combination with a long diffusion pathway and few crystal defects.

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► Design of ZSM-5 zeolites with tailored acidity.
► Development of stable and very active MTO catalysts.
► Optimal propene to ethene ratios (>5) obtained over a zeolite prepared via the fluoride route.
► Superior selectivity to propylene ascribed to low density of strong acid sites.