title: Hydrogen Transfer Pathways during Zeolite Catalyzed Methanol Conversion to Hydrocarbons.
abstract: Hydrogen transfer is the major route in catalytic conversion of methanol to olefins (MTO) for the formation of nonolefinic byproducts, including alkanes and aromatics. Two separate, noninterlinked hydrogen transfer pathways have been identified. In the absence of methanol, hydrogen transfer occurs between olefins and naphthenes via protonation of the olefin and the transfer of the hydride to the carbenium ion. A hitherto unidentified hydride transfer pathway involving Lewis and Brønsted acid sites dominates as long as methanol is present in the reacting mixture, leading to aromatics and alkanes. Experiments with purely Lewis acidic ZSM-5 showed that methanol and propene react on Lewis acid sites to HCHO and propane. In turn, HCHO reacts with olefins stepwise to aromatic molecules on Brønsted acid sites. The aromatic molecules formed at Brønsted acid sites have a high tendency to convert to irreversibly adsorbed carbonaceous deposits and are responsible for the critical deactivation in the methanol to olefin process.
authors.affiliation: Department of Chemistry and Catalysis Research Center, Technische Universität München , Lichtenbergstr., 4, 85747 Garching, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Müller
authors.affiliation: Department of Chemistry and Catalysis Research Center, Technische Universität München , Lichtenbergstr., 4, 85747 Garching, Germany.
authors.forename: Yue
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Catalysis Research Center, Technische Universität München , Lichtenbergstr., 4, 85747 Garching, Germany.
authors.forename: Felix M
authors.initials: FM
authors.lastname: Kirchberger
authors.affiliation: Clariant Produkte (Deutschland) GmbH , Waldheimer Str. 13, 83052 Bruckmühl, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Tonigold
authors.affiliation: Department of Chemistry and Catalysis Research Center, Technische Universität München , Lichtenbergstr., 4, 85747 Garching, Germany.
authors.forename: Maricruz
authors.initials: M
authors.lastname: Sanchez-Sanchez
authors.affiliation: Department of Chemistry and Catalysis Research Center, Technische Universität München , Lichtenbergstr., 4, 85747 Garching, Germany.
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Lercher