Mechanistic differences between methanol and dimethyl ether in zeolite-catalyzed hydrocarbon synthesis.

Water influences critically the kinetics of the autocatalytic conversion of methanol to hydrocarbons in acid zeolites. At very low conversions but otherwise typical reaction conditions, the initiation of the reaction is delayed in presence of HO. In absence of hydrocarbons, the main reactions are the methanol and dimethyl ether (DME) interconversion and the formation of a C reactive mixture-which in turn initiates the formation of first hydrocarbons in the zeolite pores.

Critical role of formaldehyde during methanol conversion to hydrocarbons.

Formaldehyde is an important intermediate product in the catalytic conversion of methanol to olefins (MTO). Here we show that formaldehyde is present during MTO with an average concentration of ~0.2 C% across the ZSM-5 catalyst bed up to a MeOH conversion of 70%.

Hydrogen Transfer Pathways during Zeolite Catalyzed Methanol Conversion to Hydrocarbons.

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.