title: An oft-studied reaction that may never have been: direct catalytic conversion of methanol or dimethyl ether to hydrocarbons on the solid acids HZSM-5 or HSAPO-34.
abstract: Using highly purified reagents and careful tests, we show that methanol and dimethyl ether are apparently unreactive on the two most important methanol-to-hydrocarbon catalysts, HZSM-5 and HSAPO-34. Thus, none of the "direct" mechanisms involving two to four carbon atoms in intermediates such as oxonium ylides, carbenes, carbocations, and free radicals are applicable. Only the "indirect" route (hydrocarbon pool) is an established mechanism for this chemistry. An active catalyst requires a hydrocarbon pool that typically begins with products from organic impurities in the feed, carrier gas, or the solid acid itself. Impurities may also play important roles in other reactions catalyzed by solid acids.
authors.affiliation: Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, California 90089-1661, USA.
authors.forename: Weiguo
authors.initials: W
authors.lastname: Song
authors.forename: David M
authors.initials: DM
authors.lastname: Marcus
authors.forename: Hui
authors.initials: H
authors.lastname: Fu
authors.forename: Justin O
authors.initials: JO
authors.lastname: Ehresmann
authors.forename: James F
authors.initials: JF
authors.lastname: Haw