(566e) Understanding Contributions From the Aromatic and Olefin Methylation Cycles in Methanol to Hydrocarbons Conversion

The dehydrative condensation of methanol on zeolites is
unique in its ability to form carbon-carbon bonds and concurrently restrict the
carbon-chain length based on the shape selective characteristics of the
molecular sieve. In the ?hydrocarbon pool? mechanism for
methanol-to-hydrocarbon (MTH) chemistry, organic species, specifically, olefins
and arenes, contained inside the zeolite pore act as scaffolds for C-C bond
formation. Steady state, transient, and isotopically labeled kinetic studies
were done to show that the relative contribution of the olefin and arene
methylation cycles prevalent in the indirect ?hydrocarbon pool? mechanism for
MTH conversion over zeolites can be systematically modulated at iso-conversion.
These effects of seeding the 'hydrocarbon pool' in MTH catalysis persist at
varying temperatures, conversion, and space velocity. Kinetic and isotopic
studies that probe the identity and reactivity of specific olefin and arene
components of the hydrocarbon pool, and an assessment of the relative
propagation of olefin and arene methylation cycles as a function of zeolite
topology will also be presented.