| Abstract
| - H-SSZ-13 (CHA) and H-UTM-1 (MTF) zeolites have been synthesized, characterized, and employed ascatalysts for the methanol-to-olefin (MTO) reaction. Both zeolites have eight-membered rings, and theirstructures and acidities are characterized by 27Al magic-angle spinning (MAS) NMR, NH3−TPD (temperature-programmed desorption), and in-situ IR spectroscopy. In-situ IR spectroscopy indicates that methanol isefficiently activated on the Brönsted acid sites of both zeolites. At 673 K, the methanol is quantitativelyconverted to hydrocarbons, mainly ethene and propene, over H-SSZ-13, whereas H-UTM-1 only initiallygives a small amount of alkenes, the main product being dimethyl ether. It is proposed that the limited spacein the cages of the MTF zeolite prevents formation of intermediate polymethylbenzenes and thereby alsoformation of hydrocarbons, whereas the cage size in the CHA type zeolite, which is active, is large enoughto accommodate polymethylbenzenes.
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